Welcome, everyone. This is the agenda for today. So the agenda is essentially I'll do a very quick intro. Then we'll talk about what is rules as code, or RAC, as we call it. Then I'll be talking about proof of concept that we did for RAC. And this was done for GalCMS. I'll be talking about GalCMS as well. We also did another RAC website called BenefitMe, which is actually a New Zealand website. And then I'll be talking about the process and how Drupal comes in. And then we'll be having a Q&A session. For the Q&A, we have an app. So if you have any Q&A, and if you put your questions in the app, that would be great, because my colleague here will be able to see the questions, and we can answer them as and when they pop up. Or otherwise, we can do a one-on-one as well. But doing it on your app would also work. So it would be great if you could do that. So a bit about me. My name is Suchigar. I'm a technical manager at Salsa. I've been working for 25-plus years with open source. I've been working with Drupal since 2006. Yes, 4.6 was a Drupal version at that time. I have been a dev, tech lead, solution architect, mentor, project manager, you name it. I've done it. Treino, yeah. In this particular project, the one I'll be talking in detail, I was actually a dev. It was a very interesting change of pace for me, because this was a POC, as I said, proof of concept. And we had to do it very, very quickly, two weeks, three weeks, when we were done. So we needed somebody who could really push code through. So it was very interesting for me, because I worked really hands-dirty after a long time. OK, so before we start anything, let's talk about what is rules as code? So as the diagram implies, the rules as code is a very emerging trend. It has started gaining a lot of traction. And it basically takes the legislation, regulation, and policies. And it converts that into machine-readable code. So it's not only a technocratic solution, but rules as code actually represents a shift in how governments create some types of rules and how different parties, third parties, can consume them. What are the benefits? All of us are tech people here, developers here. So I don't think I need to really spell out the benefits, but still, let's do that. There are several benefits in having a single source of truth that can drive many, many applications. The first one is, of course, reducing of ambiguity. Rules as code makes it really, really clear what the rules are and makes it more accessible and easy for citizens to access and easy for them to find the information they're looking for. It makes the whole rules very, very reusable. So once the rules are coded, they can be reused by a website, Alexa, or any third party engine, JetBots, anything. There, of course, they become very easy to manage. Once they are coded, they are easy to maintain and change. So we know exactly where the change of need to go. Revisioning also happens very easily. They become very transparent. If anybody has any interaction with government rules, they are seriously, seriously long and they are very, very difficult to understand. So converting them into code makes it much more transparent. And of course, rules as code then can be used to inform policy and model changes and how they will impact people down the line. So now in terms of the two projects, so I'm from Salsa Digital, as I mentioned, we did two projects with rules as code. The first one was a PLC, which was for GOVCMS. The other one was BenefitMe, which was for the New Zealand government. Before we talk about the project, let me talk about what GOVCMS is actually. So GOVCMS is Australia's whole-of-government website management platform. It is built on Drupal. It was designed to make it easier for agencies to create modern, affordable, and responsive websites. So GOVCMS is actually managed by the Department of Finance, which is a federal government entity. And it has actually increased the usage of Drupal in the government sector considerably. So some sort of background or context about the project. So GOVCMS actually had an expression of interest around DXP. Salsa responded to that expression of interest for digital experience platform solutions. We were successful in that. And GOVCMS asked us to create a proof of concept. Specifically, they wanted us to look at COVID vaccinations. This was in mid-2022. So at that time, COVID vaccinations were very, very relevant to help the citizen understand if their COVID vaccination status is up to date or not. So that is the journey that we picked. And that is the journey we created in the rules of code POC that we did. There were actually six potential user journeys. And only one journey really, really stood out for us. That's where the citizen is figuring out what's happening. I need some information. I'm trying to access an entitlement or trying to comply with a government policy, but I don't know what to do about that. And that's where rules is code and our POC came in. So as I say, GOVCMS wanted to look at the COVID vaccinations. It was initially when the project started, the POC started, we said, COVID vaccination, whether I need a COVID vaccination or not, that should be a very, very easy thing to do. We were very wrong. We were so wrong because going through all the legalities, going through all the rules that have been defined in pages and pages of text was not easy. So the two main journeys that we covered in our POC, one, as I mentioned, am I up to date with my COVID vaccination? And the second one was, do I have to be vaccinated from my work? Because in Australia, each different state has its own rules about different sectors. So if you're in NSW, for example, and if you're working in health sector, you have to be vaccinated, but if you're in NSW and some other sector, you may not need to be vaccinated. So we did a POC for that one as well, that particular journey as well. And this was the final product. Now, if you look at the final product, there are actually two websites that we are showing. And the reason why we are doing two different websites was to showcase the fact that the rules were coded at one central place, but those rules could be accessed by two different websites. The first one was for the general public. The second one, if you look at it, it was for the indigenous, aboriginal tourist people of Australia. And it was configured in a way that whenever they say information, that was more related to their own situation. Also, aboriginal and tourist people had different rules configured, according for the COVID vaccination policies, even the booking links that we provided them, they get a priority if they go to a booking website. So this was configured accordingly, but we created two websites. I will not be showing you the second one, I'll just be showing you the first one. This is the website either side, and these are some of the sample scenarios. A 55-year-old adult was at five doses, last dose was in June. This is DDMMYYYY, just to clarify, and that can be a confusion. A 30-year-old who was at three doses, last was third of May. A parent looking for a five-year-old immunocompromised child was at two doses, and parent looking for a four-year-old child. These are the few different scenarios or user journeys. I'll be picking up the first one to do a demo. And before I do that, I'll pray to the demo gods for a sacrifice or something. All right, so, sorry, give me a minute. Before we start, I just want you to know that this was just a POC that we created. We specifically made sure we have an alert at the top that says this is not reliable information because things keep on changing and we were not keeping up to date with the changes. But this is just a proof of concept to tell you, yes, that, yes, this thing can work. All right, so let's look at, as I said, there were two. Am I up to date with my COVID vaccinations? And the second one was, do I have to be vaccinated for my work? All right, so let's go with the first one. The first page gives us some information, keeping a COVID-99 vaccination up to date. Is why is it important, et cetera, et cetera? And then there's a button. This is all Drupal content. Nothing very specific going on here. So when we start, the way this particular POC was implemented, that it was a series of web forms. So, first web form, we input some information. When the web form gets submitted, it actually goes to the rules as code engine, which was actually coded not in Drupal, but in OpenFisca. It goes there, it gets the information back. And based on whatever information comes back, it goes to either one page or another page. That's how the whole journey was created. So for example, here, if I input something like two-year-old, now as per the rules, at least the rules at that time, a two-year-old does not have a vaccination. So if I input two-year-old here, it will actually go to a page, it will say, sorry, you're not eligible for a vaccination. And actually, let's go ahead and do that. So the moment I submitted, it actually pulled the OpenFisca engine. It sent out the information that the age is two, and the return came back saying, no, you're not eligible.  And that is why, if you see that five is actually highlighted in yellow. So this is actually the information that is coming from the rules as code engine. This is not something that is hard-coded in Drupal. So it says that you have to, and these were the tokens that we were using in Drupal. So it says that you need to be five years old and over to be a vaccinated. And how does that help? Tomorrow, if the age changes from five to three, we have to make that change only in the rules as code engine. We don't have to make any change here, and it will automatically get reflected here. Let's start over. Okay, how old are you? I'll put 55, I am not 55. So the moment I said that I am 55, now it went to the rules as code engine again, and when it came back, it says, hmm, you're eligible, let me ask you more questions. And what are the questions? Are you immunocompromised? Because, as for those treated laws, if you're immunocompromised, the rules are slightly different, and if you're not, the rules are slightly different. So that's why it's asking the question. I'll say no. And based on this one, it again goes to a next form. And then in the next form, it asks you how many doses have you already had, and what was the date of your last one? So I can say something like five, four, whatever. And let me just put in not a 2022 date, maybe this year date, 16th of, or 18th, 16th, 18th, 16th, 16th of February. And I do a summit. Oh, what is the error? Sorry, I forgot. This was, this POC was created last year, so we have to, I have to put the date, which is less than the last year. So I'll put something like 8th of December. So it said 8th of December, which was more than six months. So as for those treated laws, which we read, which we went through, it says that if you are six months or over, then you are eligible for your next dose. So that's what it says currently you're not up to date because it has been more than six months since your last vaccination date. Again, if you look at the highlighted parts, those are all the things that are actually stored in OpenFesca. They are not stored in Drupal, so everything is coming from there. And we are just displaying them as tokens. And because this is Drupal content, we were actually able to add a lot more information here. And what are the kind of information? So this was a make a booking link. And as I was saying, for the Aboriginal and the Torres Strait website, the make a booking was slightly different. It had a parameter which says that this is priority booking. So we were able to make that change. And it also gives you more information. And again, if you have had COVID in the past three months, then you are not eligible for a vaccination and you will have to have your vaccination three months later. It also gives you information about what are the recommended vaccinations for you based on your age. Again, these are all rules that are actually defined by the Department of Health in Australia. And this information, as I said again, this was coming from the rules as code. And we are just showing it up on the Drupal website. So that was the one that we did for, am I up to date? The other one that we did was, do I have to be vaccinated for my work? And as I said, this was very state-related, state-specific. In this one, there is actually not a flow of waveforms. This was just one conditional waveform. And when I said something like, okay, I am in Victoria, just to show you that there are so many states and union territories in Australia, but we did the POC only for three of them. New South Wales, Victoria and Western Australia. So I'm from Victoria. Which sector do you work in? I worked in, let's say, healthcare, healthcare. Again, this is pulling the rules as code and trying to get information from there. Because I am working with healthcare, I have to be vaccinated, and I have to have at least three doses. I could actually go back here and say some other sector. Again, Victoria, I'm thinking maybe education. Do you work in a specialist school? And that's where the conditional form actually comes in. It's not a specialist school, so you don't need to be vaccinated. There's no government requirement to be vaccinated. All right, going back to our... The other one that we did, as I was telling you, was benefit me for New Zealand. Let me actually do a very quick demo for that as well. Okay, yep. It doesn't work, sorry. The website, maybe the internet connection is not working or something. I'll come back to the demo if there is time. If time permits, I'll come back to this demo. Let's go back to our presentation. So that was, as I said, we did a rules as code for New Zealand. The rules as code thing that we did for New Zealand was essentially about benefit me. It was around what all, what am I entitled to as a person from the government? So things like, am I entitled to a household benefit? Am I entitled to an unemployment benefit, a family benefit, et cetera? So that's benefit me.nz is actually not a PLC. It's an actual website which people are using. So it was, as I said, it was around New Zealand social security benefits. And we worked with the digital AOTORA collective, sorry, it's a tongue twister. If nobody knows, it's the name of New Zealand actually. And we fed the learnings of GovCMS POC into this project as well. So that was the demo, a bit of demo, et cetera. Now let's talk about some technical aspects of it. I'll not go into deep into technical stuff, but something. So the rules as code engine that we picked for the POC and for our project was OpenFisca. Now what is OpenFisca? OpenFisca is actually an open source API first rules as code framework. And it was developed in 2011 for the French government. So we are at the right place for OpenFisca. It standardizes the way in which rules are written and provides a common request response pattern to use in connected clients. This allows integration to different systems. In this case, we chose Drupal, but it can be any other system. It can be something like a voice thing or a chat board, et cetera, et cetera. At the moment, many rules as code projects in France, New Zealand, Australia, Canada, and other jurisdictions, they use OpenFisca. Also, OpenFisca is pattern based, yeah, it's written right there, and it's open source, the most important thing. So broadly, this was our solution architecture. Nothing very technical going on here. So all the rules were coded in OpenFisca. Then we used Drupal as a content API and we used Drupal. We actually created a module which integrated web forms with OpenFisca. So we created web forms which integrated with OpenFisca, which we're able to call OpenFisca, and that's how we created our POC, or our benefitme.nz. But the whole purpose of this solution architecture was that because Drupal is a content API, this can feed into mobile apps, into voice devices, et cetera, or even rules as code, the OpenFisca engine directly feed into the voice devices, other system interfaces, et cetera, and websites as well. Now let's start with the whole process. How did we do the POC? Because the technical parts, yes, they are important, but there was a whole process associated with it. The process can be divided into, broadly, into five steps. The first step was, I would say, the most difficult one. We had to look at the rules, analyze them, and map them, and then they went into the OpenFisca and they were coded as configuration slash coding. We'll talk about that a bit later. Then, so OpenFisca was configured. Then we had a Drupal OpenFisca module, which was actually a web form OpenFisca module, using which we created web forms, which integrated with the rules as code engine, and we also used Drupal as content, using which the results pages were set up. Those were broadly the five steps. Let's talk about the first step. This is, in terms of rule mapping, this was the initial part, and it was actually really, really important because traditionally, rules and legislation tend to be written in a very, very complex way. It can be written in very complex languages. It can be written in 20 different pages, and you have to really make sure that you're going through each and every one of them to convert them into plain English. Initial rules, and as you can see, if you look at the screenshot, we actually used Miro to do our rules analysis, and we were able to do something like this using Miro. So we basically, what we did was that we get a high level model capturing the entities, the legislative requirements, the logic, the calculation, and then that was converted into machine consumable legislation. So using these kinds of, and I'll show you if you can see those clearly, you can have a look at them here, one of them. So if you look at this one, yeah, so in this case, this was a special case for where your age is greater than five, but less than 12, because that had a very different rules as compared to less than five, in which there were no rules because you're not eligible, and if you're greater than 12, you are considered an adult and they had a different rule set. So this was the flow for greater than five, greater than equal to five, and less than equal to 12, and this is an example to figure out whether you're up to date or not. So as you can see, if you're up to date or not, there are so many things that you have to capture, and yeah, again, so in this one, we were actually able to define the calculations as well. If this is this, and this is this, and this is this, then the output should be this. That is how we started to analyze our rules. So next then is the process of looking at these, and then we had to quantify and put them into the OpenFisca solution, and how did we do that? We had to, we started with creating some test scenarios. We had to then create entities, and I'll talk about entities in a minute, parameters, variables, which had inputs and outputs. So the way OpenFisca works, this is an example of a test case. Yeah, this is an example of a test case. Now the way OpenFisca works is that it has to have an entity. I'll show you in here. So to give an example, in this case, so entities could be something like an individual. It can be a household. It can be a company, an organization, based on the different rules that you have to follow. So in this case, we're talking about vaccination, right? So vaccination needs to be applied on a per person basis. So that's why our entity was a person. But if you look at the benefitme.nz example, there we were talking about entitlement, this is social security entitlement. And in that case, that entitlement is not actually on a per person basis. If you are in a family, if you have a spouse, if you have children, it becomes a household thing. So in that scenario, our entity was household. So OpenFisca plays on it. Entity is a super important thing to configure. So in this case, we configured the entity to be a person. The next step was to define parameters. So parameters, all of us, I'm hoping many of us are from a dev background, yes, no. So we do understand what are parameters, what are input variables, what are output variables. So I don't really need to explain that to you in detail. But parameters as the examples shows here is a minimum age of COVID vaccination eligibility. We actually also, because we were doing a PLC, we wanted to show how flexible the rules as code PLC is. And we wanted to also show how easy it is to maintain. So rules as code is actually versionable as well. So if you look at this one, it says that from 1st of August, 2022, the value is five. But because we were doing a PLC, and this is not an actual number, but from 1st of January, 23, the value is three. So when we were doing our PLC, if I did it today, for example, it would take the value three. So if I put five, it would actually allow me to go and say, yes, you're eligible. But if I had done this PLC demo last year, it would, if I have put my age as four, it would have said you're not eligible. So we can easily change the parameter values, and these are all date-based. So it allows us to revision stuff as well. Does anybody have questions? I'm okay with pausing and answering any questions. All right. Either I'm making it very clear, or either I'm making it very, very difficult. Nobody's understanding anything, but okay, let's go ahead. So the next thing is the variables. Variables, property of a person, or entity, whatever. So in this case, the input variables were, are you immunocompromised, which was Boolean. How many doses have you had? Right, and the second, and the third one is, what was the date of your last vaccine dose? And based on these three inputs, and of course the age was another one, you actually, let's talk about that next. So whenever we are defining the variables in OpenFisca, it actually has a value type, entity, definition period, label, and reference. And as you can see from the example here, so vaccine doses, it's of type integer. Last vaccine is of the type date, as we can see. Are you immunocompromised? It's of the type Boolean, because it can be either yes or no. It also has, of course it has a label, but it also has a definition period. Definition period is very important as well, because these things are defined on a per day basis. So that's where the definition period is here is there. The whole POC that we created is very, very defined on a per day basis. In benefitme.nz, it was on a per week basis, because all the calculations are done on a per week basis, but in this case it was based on your date, and et cetera, et cetera. So that is why the definition period here is there. And then there's a formula which then calculates an output variable. So this is an example. If this is this, this is this, is up to date, is the output formula, are you up to date? Yes, no. And as you can see, COVID vaccination up to date, the value type is Boolean, because yes and no, that's the only answer that you get. All right, so now let's come to the, so we configured everything into OpenFisca, which is an open source Python-based thing. It's totally independent. It was actually hosted on a different server altogether, because we wanted to showcase that part. And what happens now on the Drupal end? Now Drupal end actually has two parts. One is the rules part, and one is the related content part. So before I go ahead, as I was mentioning, we actually went ahead and created a web form Fisca module. Sorry that module is not yet open source, because POC time, budget, money, and also this was very, very specific to the POC we created. So what that module allowed us to do, and I'll show you some images as well there, it allows us to say, when we are creating a web form, it allows us to say, yes, this is an OpenFisca thing. It allows us to put in the URL for the API, the OpenFisca API, and the moment we start doing that, the API sends us a list of variables. So when we start creating our web form and we create each and every field, we can actually map it with one of the OpenFisca fields. So for the first form, which was very, very, the most simplest of the forms, where I set age, when I set age as an integer field, I could actually map it and say that this maps to the age variable on OpenFisca end. There might be some form elements which don't need to be mapped. We are just showing it for information purposes or whatever, and that's perfectly fine, but we were able to do the mappings. Also this module allows us to create, then once the web form is submitted, it allows us to send a query to the OpenFisca and we were able to configure what are the variables that we want as output, because those are the variables that then decided whether we want to go to a page or whether we want to go to a web form page. Again, first form, for enter three or two, the return would be no, you're not eligible for vaccination, so you go to this particular page, that's it, and so on and so forth. So web forms, and then we notes which actually, so even this branching rule which says that, okay, if the value returned is this, go here. If the value returned is this, go here. We actually made sure that this was also content-editable. We did not want to hard-code them, so we created a very simple content type which could be attached to a web form, and we could actually say if the return value, return variable x is true, go here, x is true and y is false, go here, and so on and so forth. So that was the rules content. So this is an example, and just showing you this was the rules content, so first one, as I was explaining to you, how would I use, if you submitted more than, greater than five, the rules content said, okay, you can now go to the second web, second step. The second step is, are you immunocompromised? The third step is, how many vaccination doses? When was your last dose? And accordingly, it will line to a results page. Now the results page, there were several pages which were created as results based on the different combinations and permutations. So that was the rules content flow. This particular screenshots, combination of screenshots, actually shows you how we can attach a web form and how we can do settings within the web form. So here when we go to add handler, we could actually add the openfisca journey handler which we created, and we could put the openfisca endpoint, the return value that we wanted, and you don't need to worry about this one because this is automatically calculated when we are creating the form. So this is a screenshot of when we are creating a web form, and as I was mentioning, in the first screenshot, you can see that I have created a new field, and when we go to edit the field at the very bottom, we have, because it's Fisca enabled, I have another field where I can actually see all the variables which are available in openfisca, and then I can map it here. So this was age one, this is part of the list, and I can select that, yes, this particular field is the age field. And when we create these, when we are doing this form, the UI, and when we save the web form, if you remember in the last one, so this is automatically calculated based on what we create in the UI. So that was how we created the web forms, but we also had to create the journey, so we created, this was very simple, again, POC, quick and dirty, quick and dirty. So we went ahead and created a content type called rules. It had one field which was for the web form, and then within that we could have multiple things. So this is the simple one which says if the return value of COVID vaccination eligibility is false, redirect to this page. If it is true, redirect to this page. This is the simplest one, this is a more complex one. So this is the last one, the last form. So we get so many return values and we could put in a combination of this is true, this is false, this is true, go here. This is false, this is true, this is true, go here, and so on and so forth. So we created, in Drupal we created a lot of result pages based on the requirements. As I said, Drupal part had two parts, one was the rules content, we just talked about the rules content, and this is about the related content. And related content is actually the content we created in Drupal, and we, as I was mentioning, we used tokens a lot. So whatever was being returned, we showed them as tokens, and all the results page that you see here, they're all rules pages. And these are the pages that we are being redirected to using the earlier one, using this one. So you're not eligible for a vaccine is a page. And similarly about your COVID vaccination history, it's another page. Right, actually I'm very, very early. All right? I'll take questions here. All right, so we have two questions. So the question is, is it possible for a client to change the rule themselves, or it has to be done by a developer? The rules themselves, they need to be done by a developer because they are the ones that are coded in OpenFisca. The rules is code engine, so that needs to be done by a developer, but the whole flow, et cetera, that can be done by clients. And so the question is, I think the strength is the web form slash OpenFisca integration module. And so maybe the community help and create a dev branch. I totally agree. But I'll tell you, one of the reasons were of course, time and money that we didn't have time to make it a... The other reason was also the fact that, not always we did not need that, we needed that module, yes, but not always we were using the same flow. So in the benefitme.nz example, we did not have a flow of web forms. It was one big huge web form. And then once that is submitted, so web form OpenFisca module, yes, it is needed. And yes, we can talk about, I can go ahead and create a dev branch or something on, we had plans about making it open source. So if anybody of you is interested, please contact me and we can talk about that and we can make it open source, at least a dev version, so people can take and plan accordingly. But I'll have to warn you, it's very dirty at the moment, but that's how everything begins. So yes, we can do that, yes. Which, so the question is, are the YAML files stored in your repository or the OpenFisca? Are you talking about the rules YAML files? They are, so the rules engine is a totally separate thing and the Drupal part is just an integration. So rules engine is stored, everything is stored. The YAML files that we show, the examples that we show that we saw, they're all in that OpenFisca, they are not in Drupal. The question is, is this only to be used for legislation or can it be used for brands, et cetera? It can be used anywhere. It's just a PLC we did for legislation and government, but if brands need, yes, I can understand what you are talking about, that if you have a huge organization and you have different brands, but there are some rules that need to be followed for all brands, yes, it can be used there as well. So the question is that rules are in a book or on a website, et cetera. That was actually covered in the first part of my presentation. So yes, that is a manual process. The rules have to be read through and I can actually show you the diagram very quickly if possible. So we use Miro to extract that information and try to convert it in a way that it could be then coded. So that is, yes, that is a manual process. Any more questions? Thanks all for joining. Goodbye.


so we okay okay okay okay relax we're here for the record i didn't ignore you guys it's just you really can't appreciate how incredible something is until you have something to compare it to dolly is the standard and i really wanted people to understand dolly so they can see the differences between it and other software so there are actually two sexy ai's stable diffusion and crayon now crayon is that underdog that i'm secretly rooting for and the reason for that is simply because the quality is rapidly improving but more importantly they have a completely limitless unrestricted policy which kind of makes sense because i think the same guy has worked on both crayon and stable diffusion i could be wrong on that but feel free to correct me in the comments i had some hope for mid-journey in the beginning but it looks like they're slowly going down the same policy path as dolly and will probably be banning more and more content as time goes on so if you want to search things that would almost definitely get you flagged in normal circumstances stable diffusion and crayon are the way to go crayon used to be known as dolly mini they changed their name after having a debacle with dolly normal and what i like about crayon is this is by far the most user friendly ai interface ever created you don't even need an account you can come from anywhere in the world to this site type anything you want in this box and a minute later it will spit out nine images that you can use commercially as long as you attribute crayon in the credits it still struggles a bit with people but it's literally everything you could ever want in an art generator no rules no limits complete commercial freedom with the simplest user interface in the entire world you can make beautiful environments concepts you can even type porn if you want like i said it's still not really good with people so you'll probably get some creepy stuff but honestly if we could just get crayon the resources they need to improve their quality i really think they could be the one but until crayon does get its resources i think our best bet is stable diffusion and that's why for the end of this series i will be covering stable diffusion just like crayon they do not limit or tell you what you can and cannot create and the quality of images that you can generate is rapidly improving stable diffusion just about single-handedly keeps dolly and potentially google party in check but the only real way i see google party defeating stable diffusion is if they adopt the same open policies otherwise i think they'll inevitably sabotage their own user base the way dolly seems to be doing right now i don't really see them being okay with that so i guess we'll find out but as it stands we have hope stable diffusion is pretty awesome and if you join me next video we will be comparing it to dolly so hope that helps and as always hope you have a fantastic day and i'll see you around


is the top of the hour. So we've got a good number of people, but a few more people are gonna filter in and so let's go ahead and get started. And so hello everyone and welcome to the December NASA Night Sky Network member webinar. We're hosting tonight's webinar as usual from the Astronomical Society of the Pacific and San Francisco, California and our remote site in Potsdam, New York for those of you who are familiar with that part of the country. We're very excited to present this webinar with our guest speaker, Dr. Jerry Bennell from the University of Maryland and NASA's astronomy picture of the day. Welcome to everyone joining us on the live stream. We're very happy to have you with us. These webinars are monthly events for members of the Night Sky Network. For more information about the NASA Night Sky Network and the Astronomical Society of the Pacific, we'll put some links into the chat in just a couple of moments here. So before we introduce Jerry, here's Dave with just a couple of announcements. Hi folks, I'll get this done real quick for you. First of all, just so you know, if you got the alert a little late for this webinar, some messages got stuck when I sent this out and I managed to get them out. So apologies if you've got a light notice, but you're here now and that's great. And just a heads up also for folks who ordered pins the fast few days, getting them stuff wrapped up. They will be shipped either later this week or early next. We had a bumper crop of orders, which is lovely, but they will get to you soon. And I'll send you all notices individually after this. Also, one more thing, it's just the last chance for me to say this. It's a great time to add your club's upcoming events to the NSN calendar for 2022. As long as your holiday season isn't too hectic, of course. When that happens, by next year, you'll already have all your events added in advance, it's making updating and reporting on them easier. And plus you may qualify your club to win one of 20 Galactic Quest 4-H kits. And I'll put those links in the chat in a second. And that's it as far as I know. I won't be holding off our main topic any longer. Back to you, Brian. All right, thanks, Dave. So for those of you on Zoom, you can find the chat window and the Q&A window at the bottom edge of your Zoom window on your desktop. Please feel free to greet each other in the chat window or to let us know if you're having any technical difficulties. You can also send us an email at nightskyinfo at astrossociety.org. If you have a question for Jerry tonight, please type it into the Q&A window. That really helps us keep track of your questions and we don't lose them in the chat. And speaking of the chat, another reminder, please make sure that you select everyone at the bottom of the chat window so that we can all see your greetings. We'd love to hear from all of you out there. Okay, so I'm gonna hit the corner. So again, welcome to the December webinar of the NASA Night Sky Network. This month we welcome Dr. Jerry Bennell to our webinar. Dr. Jerry Bennell received a PhD in astronomy from the University of Maryland at some point during the last century. He has since enjoyed working on a variety of astrophysical satellite projects at NASA's Goddard Space Flight Center, including the Cosmic Background Explorer, the International Ultraviolet Explorer, the Compton Gamma Ray Observatory and the Fermi Gamma Ray Space Telescope. Sounds like a regular tour of the great telescopes there, Jerry. While his research interests have wandered across the entire electromagnetic spectrum, they've most recently focused on the time histories and spectral evolution of cosmic gamma ray bursts. He's the author of some popular books, reviews and magazine articles on astronomy and high energy astrophysics. And he's also the founding editor and author of Astronomy Picture of the Day along with Robert Nemeroff, who we had last year for this particular program. They began that together in 1995. Dr. Bennell lives with his wife and art historian in Greenbelt, Maryland, USA. So please welcome Jerry Bennell. Thanks, Dave. Thanks, Brian. At some point I share my screen, right? This is how good I am. Whenever you're ready. We might be sharing a screen now. It looks exactly like we want it to look. Okay. Okay. Thanks, Brian. Thanks, Dave. Thanks for inviting me to give the Night Sky Network webinar for December 7th. I understand that my colleague in arms, Robert Nemeroff, often gives such webinars to the Night Sky Network. So this is my first time. Bob Nemeroff and I have been doing Astronomy Picture of the Day, a website run out of Goddard Space Light Center for a few years now. I think it, as mentioned in 1995 is when it started. And tonight I'd like to show you some pictures from that website that we featured in 2021. So, and I sort of like the travel log metaphor. So I think I'm going to try to do something like postcards from the universe. Pictures from Astronomy Picture of the Day, 19, or 2021. The one on the title slide here is, is as it says Apollo 14, Heads for Home. I wonder if it looks familiar to you. There's a, there's an actually a very famous image from Apollo 8, the Apollo 8 mission of Earthrise. The Earthrise over the limb of the moon. This is a similar one from Apollo 14. So what you're seeing here is, well, Apollo 14 actually would have been enough in 1971. So that would be 50 years ago. This 2021 would be its 50th anniversary. Apollo 14, I think was Shepard Rusa and, sorry, I can check my notes here. Oh, Mitchell was the lunar module pilot. So this is, but this is all three of them in the command module coming around the far side of the moon. And as they, as they orbit around the moon, they see the crescent Earth rising there under the limb. So that's the far side of the moon, the unfamiliar side in the foreground there. They see it rising because of their orbital motion, right? When Shepard and Mitchell were actually on the lunar surface, the Earth just, just hangs in their sky. It's more or less steady at a spot in the sky. But because of the orbital motion, the moon is locked in tidal rotation. And because of the orbital motion, they can see the Earth rise and set. Anyway, Apollo 14 heads for home. It's a good start to the travel walk here. Let's, sorry. Yeah, so let's travel to France for a moment. This was, I thought it intercedes the mission late in 2021, but it's actually a picture, a photograph of the summer sky, sort of late night summer sky. From a plateau in the French Alps. So this is at the substantial altitudes, say maybe 7,000 feet or so. The sky's very clear. The night sky's very clear here. The foreground is lit by moonlight. So this is a picture taken near moonset. And these two friends have been hiking through the Alps for the day and they're admiring the view. It's an interesting view. And it strikes me that it has almost, well, it has a literally extra galactic perspective.  It's also very much, it also reminds me, it's very evocative of what you would see with the eye. If you were there on this hike. This is the Milky Way. You can sort of see running down the left side of this view of this frame here. So this is Cassiopeia. This is Perseus down here. So this is the stars. Stars in the plane of our galaxy, the Milky Way. Right above them here, I see another galaxy, the Andromeda galaxy. Also, you're a fan of the night sky. I bet you've seen the Andromeda galaxy. That's an easy naked eye object. An easy extra galactic naked eye object. Two and a half million light years away. It's how far you're looking there. I think the photographer Martin LaFrance realized maybe only after he made this image that right down here, right between the two friends is another galaxy, the Triangulum galaxy. M33 is this very fuzzy spot here. So these basically are the three galaxies in the local group. The three largest galaxies in our local group. M33 is the smallest Andromeda is the largest. Milky Way is the middle man in size there. Quite an interesting extra galactic perspective, I think. Had the two friends, let's see if we can do this. Had the two friends actually been on that hike five billion years from now. They would have seen something like this. The very top frame here is an illustration, not a photograph of, well, a horizon. And this is the Milky Way galaxy. And this is what the Andromeda galaxy would look like about five billion years from now when Andromeda and the Milky Way galaxy began to merge. Andromeda is headed for us. Although it will take a while to get here. The sky will look really spectacular when it does get here. In fact, the third galaxy in the photograph, the galaxy between the two friends was the Triangulum galaxy. That's this frame here. A telescopic image of Bernard Miller. I really don't have a good image to illustrate this but ultimately, of course, the Triangulum galaxy will join the Milky Way and Andromeda in a merger. I just note the Milky Way plus the Andromeda galaxy you would probably call that galaxy, Milkdromeda, or what it's worth. And I tried to think of something to call the three galaxies when they were all merged, five plus billion years from now. So I went for Triangulumdromeda, I don't know. I expect that there are people that could do a better job. Have a few images of Mars here, sort of snapshots from the Perseverance mission. Mars 2020 mission actually landed on Mars in February, I think of 2021. This top one, Perseverance How to Land on Mars is actually a snapshot of the Perseverance itself Perseverance itself being lowered to Mars surface on these three cables from the descent stage. The descent stage is rocket powered. So it's a rocket powered sky crane, if you can imagine, was lowering this rover down these cables to the Martian surface. These cables, I have in my notes here, these cables are about seven meters long. And at this point, which is actually a frame from a video that's being made with a camera on the descent stage, the rover itself is about two meters above the surface at this point. You can see the rocket engine exhaust is blowing the dust around the surface of Mars. In Jezero crater was a Delta near one side Jezero crater was the landing site. This is an electronic umbilical signal cable. In fact, it's connecting to the computer on board, the Perseverance rover. And it's almost a selfie in the sense that the image, this image is being recorded by the computer being transmitted through this cable to the computer on the rover for a later broadcast to Earth. Of course, after the sky crane drops off the rover on the surface of Mars, these cables are detached and the descent stage flies away nearby and crashes far enough away so as not to contaminate the landing area. Just to prove, well, I'm sure everybody's seen images from the Perseverance Mars rover mission. This is say a month later or so. This is a selfie, Perseverance rover and this is Ingenuity, the helicopter, the little Mars helicopter it thought with a few snapshots from Mars. This top one, we're still hanging out on Mars here except this is the Curiosity rover. It's a mission that's been operating on the Martian surface since 2011. And I just thought this was an interesting shot of clouds on Mars, night shining clouds on Mars. This butte in front here, this sort of layered mound is called Mountain Raku. The curiosity was parked nearby in this image was made near Twilight. And so the sun has set on Mars as seen by the Curiosity rover but the clouds are shining still because they're very high altitude, extreme altitude clouds and still in sunlight even though the ground is in shadow. So on Mars, those clouds would probably be carbon dioxide ice, dry ice, crystals, very small as I say at really extreme altitudes. We have that same sort of thing going on on Earth. The bottom panel shows you Northern Summer Twilight by Justin Anderson. It shows the clouds that you see these silvery wavy clouds along the horizon in the distance there are not the lucent clouds, night shining clouds on Earth. They're waterized though, I think. And we tend to see them on Earth in the summer months at very high latitudes. Once again, the sun is below the horizon and you see these clouds shining because they're still in sunlight at such extreme altitudes. One, I guess one big difference might be that in Justin Anderson's view all these little green spots of light are fireflies, probably not fireflies on Mars. When I was putting this together I think I had trouble getting away from Mars but let's do a few more Mars pictures. Actually, the one at the upper right is not so much Mars but it does look like it. On Mars, the sky is is this reddish brown because in the Martian atmosphere the Martian atmosphere is dusty. There's very fine dust on Mars. The dust is iron oxide, that's rust. That's why the dust colors the sky of sort of a reddish brown and the Martian sky sort of reddish brown. And on Earth, of course, the sky is blue but in this, the upper picture here was taken in the Swiss Alps at a ski resort on planet Earth and the dust that's in the atmosphere that's scattering the blue light and turning the atmosphere on Earth this reddish brown is from the Sahara. It's the Sahara dust on blowing across the Swiss Alps there. Looks like Mars. Another image that caught my eye was also a little like Mars by Robert Barca here. This is, it's a little planet projection. It's called, it's a 360 degree panorama with the nadir at the center. So it's been projected and this is the horizon and this is the sky, it's an all-sky panorama. Robert Barca's at San Pedro in Chile in the Atacama Desert. And the Atacama Desert is what the foreground here is. It looks a lot like Mars. You have to, it's a Southern Hemisphere sky. So I bet you do recognize some things in the sky but for example, this is Orion. Although from the Southern Hemisphere perspective you might notice it's upside down. So there's a beetle juice down here, right Jill up here. The large Magellanic cloud, small Magellanic cloud, good Southern Hemisphere objects. And actually in Barca's photograph, he did get Mars as well. This is Mars in the night, in the Southern night. I was still cruising through the solar system here. I guess in 2015, maybe Rosetta mission was launched in 2014. Arrived at Churyumov-Gerasimenko and this is a photograph from the Rosetta spacecraft, the European Space Agency's Rosetta mission spacecraft. It's actually, it's a photograph from the lander, the Filet lander on the spacecraft, which is still attached to the spacecraft in this picture. This is the sort of the sun glinting off the solar panel. This is one of the spacecraft solar panels. And at the very top, you see the sort of double lobed nucleus of Churyumov-Gerasimenko. If you get tired of saying Churyumov-Gerasimenko and you don't want to call it Rosetta's comet, you can always call it comet 67P. It's a P for periodic. It's the 67th on the list of periodic comets. And it has an orbital period of six point something years, six point four years, something like that. And so this Rosetta mission arrived, as I say, I think in 2014 or 2015, stayed with the comet, I've explored the comet, the Filet lander actually landed on the comet and the Rosetta spacecraft was actually driven down to the comet during its last perihelion passage. But it's come back. It's new perihelion passage. I think was in, its most recent perihelion was in November, early November. And so the comet was back in our skies. This is a nice picture from Rolando-Lacustry. A look of Rosetta's comet 67P while it was in the constellation Gemini. These are stars in Gemini. And I think this is light coming in from Pollux. They're a beta Gemini or one of the two bright Gemini twin stars. So when you see this comet, when you see photographs of this comet, this is actually the resting site of the final resting site of the Rosetta spacecraft and its lander as it comes by the sun again. Is it actually another comet? Fairly bright, although possibly not a good, certainly not a good naked eye comet in the sky in 2021. Or as we continue through the solar system here. This is comet Leonard. Comet Leonard was discovered early in the year. And this is a picture of it. It's getting brighter now. I think it's near its perihelion. It's certainly near its perigee, its closest approach to Earth in December. It's in the foreground, but fortuitously along the line of sight to these two interesting galaxies. This is one that's popularly called the whale galaxy because I guess it looks a bit like a whale, especially in this picture. And this is the hockey stick, the hockey stick galaxy, two interacting galaxies with the comet along the line of sight. The comet is actually a few light minutes away in this image. The galaxies are like 25 million light years away. So they're quite in the distant background. Comet Leonard has no spacecraft associated with it and will not. This is comet Leonard, unlike Cheryumov-Garosomenko, it's not a periodic comet. It's on a hyperbolic orbit. It's a one time, I think it's perihelion, its closest approach to the sun will be in January. And then it's out of here. And if you think about it for a minute, it's hard to plan and execute and launch a mission to a comet unless it's periodic and you can actually plan over a period of years and match orbits with the comet over a period of years. The comets that just come in, swing around the sun and go out are hard to catch, gonna be hard to catch for a spacecraft. Well, we'll get out of the solar system here eventually. This is, well, it says 50 light years, the 51 Pegasi and there is a 51 Peg circle for you in the top center. It's a picture of the observatory, the whole Provence in France, where Michel Mayer and Didier Keralos worked and discovered the first exoplanet around the Sunlight Star, around the Sunlight Star 51 Peg. So, this, their discovery would have been in 1995. Actually, that's a good year, that's about the year. I've never often, I started up with A-Pon. Not that it was, that was anywhere near as profound as the discovery of the planet around 51 Pegasi. 51 Peg B, the first exoplanet and 51 Peg B was initially the planet's name. It's, of course, at this point, there are 4,000 plus known exoplanets. Many of them discovered by space missions like, well, many of them discovered by the Kepler mission. This one, obviously, based on ground base, or discovered by ground base astronomers. 51 Peg was detected by measuring the dockler shift, the wobble that the planet produces on the star spectrum as the planet orbits. And so, it was, I think you can time it, you can determine its orbit, you can estimate its mass, the mass of the planet. And 51 Peg B was estimated to have the mass about, I don't know, about half, at least half, maybe more than half the mass of Jupiter. It orbited 51 Peg every four points of time in the coming days. So, it's sort of a Jupiter-sized planet that orbits its parent star closer than Mercury, orbits the sun much closer than Mercury, orbits the sun. And it turns out to be sort of the prototypical, archetypical example of a hot Jupiter, which now that we've seen about 4,000 exoplanets, hot Jupiters are relatively common, not unusual, non-exceptional for planets and planetary systems. Incidentally, I think Mayer and Kalos got, I think that was the 2019, they shared the 2019 Nobel Prize in Physics for this work with James Peebles.  It's probably 20,000, 30,000 light years out in the halo of our own galaxy. And it's one of the brightest globular star clusters in the constellation Arceus. Known as the great globular cluster in Hercules. This is a very nice image of this really dense sphere of stars here. Now, these stars that you see with spikes around it are definitely in the foreground. This is a ball of a few hundred thousand stars, let's say, in a diameter of about 150 light years. At the core, yeah, well, you can see the individual stars was all in the image around the outside of the cluster here. But at the core, the density of stars is rather large. In fact, I think if you took a cube, three light years on the side and put it at the core of a globular cluster like M13, you could probably count a hundred stars within that cube. If you took a cube, three light years on the side and put the sun at the center of it in the solar neighborhood, you wouldn't find any other stars. The closest star system to the Sun Alpha Centauri for something might be years away. So, it's very dense in the core of that globular cluster. Many years ago, a naturalist photographer, wildlife photographer, Roger Hopkins, sent this image to Astronomy Picture of the Day. It's an image he took at a wildlife preserve in upstate New York. I wish I could name it, maybe Dave would recognize it. Of what he described it as, what he thought sunset would look like if he lived on a world in the center of, an orbited star in the center of a globular cluster. Then I thought it was pretty clever. And you can see as the sun is setting and the stars are beginning to come out, the sky is very densely populated with stars. I think what Hopkins has done here is he's photographed a flock of birds flying above the water here and manipulated the photo to turn the birds, the black dots of the birds in the stars, a flock of stars, sunset in the middle of the globular cluster. Staying, hanging around in the plane of our galaxy, you could travel to a star-forming regions like M16, the eagle nebula here and one of Adam Block's nice images. This is a cluster of stars inside. It's sort of natal molecular cloud that the star cluster formed from. And you can see the stars as the stars, winds and radiation from the stars sort of sculpt away and carve away at the dusty regions. We compress the gas and all these dense features. Stars are forming inside these features. So new stars are being born here. There's a famous Hubble image called the Eagle's eggs of this particular formation right here and another famous Hubble image of this extension here, or star formation. In the image here by Robert Eater, Eater has taken out all the stars that he can see. He's usually processed them away to leave just the star stuff, the star-forming material. In a nebula IC-4443, it has this famous feature in it called the elephant's trunk nebula. And although Eater has taken out all the stars, he can see there's still stars forming down inside the elephant's trunk here, which I guess you could see if you could look in infrared light, you would see some indication of the star formation going on inside there. These features as well, I only recently learned that the popular name, well, the popular name for this is the elephant's trunk in IC-443, this is the caravan. These sort of star-forming pillars are popularly known as the caravan, so elephant's trunk and caravan. If you wonder, well, let's look at it this way. If you were just in interstellar space near the sun, you could probably count one atom of hydrogen in a cubic centimeter. If you were to fly in your starship through one of these regions, one of these regions we see as these nice nebulae, maybe you would count in a cubic centimeter, maybe you would count 10,000 atoms of hydrogen. So they are quite a bit denser than the local stellar neighborhood. That's why we see them in, we still see the star stuff, we still see the nebulae. Of course, if you were to try to count the air molecules in the room you're sitting in, in the cubic centimeter of the room you're sitting in, you would count 10 to the 19th or something like that. So you would count a 10 billion billion compared to 10,000 compared to one in our neighborhood. You were wondering how dense that was if it would affect your travel plans at all. You have any travel plans to go here? I don't know. I'm a big fan of Star Trek, for example. And if my starship were going anywhere near here, I would put the shields up. That's the word because this is the crab nebula pulsar. And it's been imaged by the Hubble Space Telescope and by CX of Chandra X-ray observatory. So this is a mix of optical and X-ray imaging of the crab nebula pulsar. And I would say this distance through this inner ring here is about a light year. So this is a pretty enormous amount of space. Enormous, still a pretty enormous, basically a particle beam weapon, almost. It's a pulsar is spinning 30 times a second. Its magnetic field is dragging this, is formed as torus of energetic particle. Relativistic particles are shooting out the beams perpendicular to the pitch and axis or along the rotation axis of the torus. Of course, the crab pulsar is, and the crab nebula is a supernova weapon. The crab pulsar is the core of, the collapsed core of a star that exploded around 10,000 years ago and was observed in records. There are records of it when it's light reached Earth. And of course, the nebula is the sort of expanding or expanding debris cloud shield top for a tour of the crab nebula pulsar, though. Yeah, one of the problems with sort of using astronomical images to tour around the universe is, well, let's, it is sort of the view, the vantage point is not, you're not really in control here, but I like this pair because, well, consider this. An external galaxy, the whirlpool galaxy M51, very bright galaxy. It's one of the original spiral nebulae that people would make drawings of. You can see the spiral structure in a large telescope and see it visually. You don't need to photograph it. It's one of the original spiral nebulae back when there was a debate as to whether these were actually external galaxies or just spiral-shaped nebulae within our own galaxy. They are, of course, external galaxies, but they did be a million and a half years away for M51. It has this nice spiral structure. You see all these red star-forming regions like the eagle nebula all along the spiral arms.  You can tell that the companion galaxy, I think, is behind M51. It's not exactly in the plane of M51 because it looks like that dust structure goes in front of it. But if we had a starship, we could try to fly around and look at it from the side. And I think if we looked at it from the side, we'd see that this system really, from the side, looks something like this. This is a flat. This is the plane of a spiral galaxy. Spiral arms, you can almost guess that these are spiral arms that sign here. And this is a companion galaxy that it's interacting with along the side. So I think this is the side view. This is the face-on view for systems like this. We can't really fly around them in the starship, but we can figure out what they look like from a different perspective. I have actually forgotten, and I'm seeing my notes. Oh, is this 1543? The galaxy in the river, this is as an NGC number. It's a bright galaxy, but it's in the Southern Hemisphere, not in Messier's Catalan. It's in the river, it's in the constellation of the river. It's in Eridanus. If you were a fan of the Southern sky. I may flip through here pretty fast. We're obviously visiting, we're obviously in extra galactic space here. This is a famous image of Messier 101 from the Hubble Space Telescope. It's a very high resolution image of the galaxy at its full resolution from a 2.4 meter telescope in low Earth orbit. And this is a pretty high resolution image of Messier 31. The galaxy's a little closer. It's about 10 times closer than M101. But this image, M101 was imaged by Hubble from low Earth orbit. This was imaged by Robert Gendler from his driveway in Connecticut with his 12 inch cast-a-grain telescope. I enjoy the comparison between the amateur work and the professional. We've moved out of it. Now I think we're closing in as far as we can go here. Galaxy cluster ABEL 370, four billion light years away. Galaxy's coming clusters, by the way. Where's a good place to find a galaxy? If you look out into the universe, the answer is right next to another galaxy. They come in clusters. They come in these large groupings of galaxies, which you see all together with you if you can look at far enough. The cool thing about this image is you're actually seeing beyond this galaxy. You're seeing galaxies far beyond this foreground galaxy cluster, which is four billion light years away. The galaxies behind it are showing up as these streaks, these curved streaks. The gravitational mass of the galaxy cluster, ABEL 370, is dominated by dark matter. And it's so massive that it's actually a lensing, it's called gravitational lensing predicted by Einstein's general relativity about 100 years ago or so. Anyway, we're looking, because of gravitational lensing, the cluster ABEL 370 is acting a bit like a telescope lens showing us light from galaxies far behind it, although stretched out into these long these long arcs. Spectroscopically, you can determine properties of those distant galaxies. So thank you Einstein and gravitational lensing. Okay. I think I'd probably welcome to the end of the tour here. I had to work this in somehow. This is a slide that this is an image submitted to APOD not too long ago that was one of my favorites. I guess this might fit into a terrestrial, a more terrestrial travel talk. Basically, the pixels are the moon as you might have guessed. The moons, they're all, it's all natural colors of the moon. They're just pictures of the moon taken at different altitudes, different seasons, different phases arranged into, like I said, pixels in an image. And you might recognize the image as the Mona Lisa, right, which would be, which you would normally have to travel to the loop and to see. But here you go, the Mona Lisa. And the way to see, I think the way to see it most easily, you could stand back from your monitor a bit or you could just look and look at smaller and smaller images until you might actually recognize the Mona Lisa, no Lisa. The tie-in with the venti that really impressed me was, Martella has used for the darker pixels here. The moon, that's the color of earth shine, for example, that's the bright crescent moon and this is earth shine. When you can see the moon by light reflected from planet Earth, you can see the night side. The venti actually explained what earth shine was 500 years ago. The Mona Lisa in earth shine, the venti. And the end, it says the end. Let's stop here. Let's stop here. This is actually an old image of the Telyabinsk meteor flash. My goodness, that was in the Telyabinsk meteor and an air burst over Telyabinsk, Russia in 2013. The photographer out for a morning stroll happened to catch the air burst. I'd just like to end with that slide, Brian. That's a good place. I don't remember which one it was. It might have been the dark mission, but a couple months ago we had a webinar on, it probably was the dark mission about all these asteroids and the mission to go out and redirect, see if they can alter the course of... So we saw some of these videos during that one. That was pretty spectacular. Well, we do have a number of questions here and so let's get to some of them. And so we've got one question says, what makes some comets periodic and some just a one-time only? I think comets... questions, questions. I think comets... there's a reservoir of comets in the Oort cloud, right? That's 100,000 AU or so from the sun. It's a big spherical cloud. We know you can plot their orbits so you can see where they came from. And the non-periodic comets come in from the Oort cloud. What put them out at the Oort cloud? I'm guessing that they're scattered out there from maybe from closer in and the solar nebula when the solar nebula was formed. The periodic comets seem to hang out or perhaps they were captured in interactions or seem to hang out inside the orbit of Neptune or even closer. And there are, you know, 100 or so periodic comets known. And I don't know the... I should just say, Terry, I don't know the answer to that question, but I know who to ask. You ask a planetary dynamic. There we go. So we had some interest in the nebula. I thought it was really interesting when you related the density of them. And, you know, speaking of Star Trek and some other science fiction movies, it seems like a common theme is that the spacecraft go and hide in the nebulas. Yeah, that doesn't really... Yeah, hide in the nebulas. Actually, I did have one question in a talk years ago. Someone wanted to know, if they flew through one of these nebulae, would they need windshield wipers, right? And that's what got me thinking. That's why you can answer a question like that, because that's what got me thinking. I don't know if you would need windshield wipers or not, but I do know that it's 10,000 atoms of hydrogen as compared to 10 billion-billion molecules of hydrogen. Still a pretty good vacuum. Yeah, still an excellent vacuum by 15 orders of magnitude. Yeah. So kind of staying with that. And so we have a question about the hydrogen that were in these molecular clouds.  If you were to travel through it, would the friction of the spacecraft possibly ignite it kind of in the same vein as the other one? No. Well, you know, only if you were traveling through it at some significant fraction of the speed of light and happen to run into one of those atoms of hydrogen, then I think you could, I think you could, I think you could, I think you could, I think you could, then I think you could, I think you could get some sort of, you know, nuclear detonation. Otherwise, at normal automotive speeds, I don't think there would be any friction or any problem there whatsoever. Have I gone too far with that? No, it's a good question, though. It's, you know. Yeah, it is. Once again. And it could actually pose the question.  Well, when you say, when you say nuclear bomb, I'm thinking about a fusion bomb, a fusion reaction, a fusing to nuclei. Yeah. Of hydrogen. But it's a good question to think about the different processes that take place to. But you won't get that from friction, like we think of friction, you won't get the fusion reaction from friction. You might at half the speed of light smack into a hydrogen atom and cause a lot of trouble there. So kind of staying with the, with the density of the nebula. And so we have another question. How is the density of a nebula determined? How can we figure that out from here? Yeah, the spectroscopy, the great tool of the discovery of astronomy, you know, discovered in the 20th century. The motivating, building all these large ground-based telescopes, spectroscopes allow you to measure the intensity of spectral lines and identify the atomic species that they come from. So density, you get density and temperature out of modeling. The plasma that produces the spectrum that you observe. So that, that's how, in the first place, the lines that you see are, the lines that you see in the nebulae, for example, won't occur in the laboratory, except they require, they're forbidden lines often, or combination lines. They require very low densities for the transitions to take place in the first place. So the fact that you see them at all means that density is very low. And then the intent, the relative intensities of the lines can let you determine exactly what the density is. So we've got time for a couple more questions. And some of these, I mean, I'll lump together, but here's the last kind of science question, and we'll kind of do some more practical ones. And so do dark matter and dark energy interact? And so you had alluded to that. Oh, I see this. Yeah, dark matter and dark energy. Yeah, I mean dark matter is dark, is called dark matter because we don't see it. We know it's there because it's gravitational matter. It influences the orbits of things. It's keeping all those galaxies in that cluster, in a cluster that's doing the lensing, the gravitational lensing. So dark energy is the sort of additional energy that's making, producing the universe's expansion. That's sort of countering the gravitation on large scales and expanding the universe. So in that dark matter is gravitational and dark energy is causing the universe to expand and contract. Yeah, they do interact. Okay, next I'll ask a question. And so a number of people have asked about how to go about submitting photos to astronomy picture of the day and what are the criteria for selecting them? Submitting the photos. If you go to the website and you look at it, the navigation bar along the bottom of one of the picture pages, you'll see a submit. And if you put that submit, you'll go to a page which says mail to links. And the bottom line is just going to be submitting a photo. You should submit it by email to Robert Nemeroff and Jerry Bonnell. He says submit it to both editors. So we both see it. If you want, if you want to give us both a chance. And the email is addresses are in that submit link. I just posted the link to the chat too. Oh, thank you. Yes, that's it. Submit 2015. Awesome. So once they submit them, what kind of criteria do you use? Because I'm guessing that you get a lot of submissions. Yeah, we do. Yes, we do. Yeah, it's gone from. Right. I'd say. In the early days, we definitely were not driven by submissions of images to a surrounding picture of the day. But now we are, it's the vast majority of images are submitted. And it's, it's difficult to choose. And so. Of course, we look for good technical images, but also we look for good topical images. As well. And by topical, I mean, there are often there are, there are conjunctions, eclipses, comets, things like that. So. And so I do, I do appreciate that. Well, there's only 365 days, usually a year, right? And so I would say we are oversubscribed by a factor of 10 or 20. There's 10 or each day. There's probably easily 10 images. I would, I would have put up for that day. So I have to figure out some way to choose. And like I say, it's, it's tough, it's tough, but it's not always. I mean, I don't, I don't really do it as a popular contest. Yeah.  I do, I do. And so what sort of images catch my eye? I don't know. I'm always, I've always been a sucker for a big, beautiful spiral galaxy. How about that? Well, this might lead into the last question and I apologize to the people. Those questions were not going to be able to get to. And so this question is kind of akin to asking which of your children you like the best. What's your favorite photo that you've published and do you have a favorite? I guess it sounds maybe it's a spiral galaxy. Could be. I could, I could, I could show it to you. Oh, please. I have it. In my talk. Oh, God. Here, but all I had so. And so I'll tell you what I'm trying to do. And so if I mess up, you'll. I'm going to share my screen and I'm going to show one last slide from that talk. All right. Excellent. And when I do that. Oh, well, that was easy. Let's, let's go on to a few backup slides. I'd say, I don't know. I have trouble asking what's, what's your absolute favorite image? But let, but let's pick this one. This, this is, this would come close. This would come close. And I can tell you why I like this one. And maybe it will. It'll help the selection question. So I'm going to show you some of the stuff. It is a spiral galaxy, although this one is, is a spiral galaxy on edge, right? And you see 59 or seven. So this is the plane of the galaxy. And if you could see it face on that edge on, you would see that it had spiral arms. Spiral galaxies of this very thin plane. This is. This is the ghost of the galaxy. This is the ghost of at least one galaxy. That was orbiting this. Spiral galaxy and what an orbited a few times before it was, before it was consumed by the galaxy. So this, this sort of galactic cannibalism is, I think our understanding today is basically how large galaxies formed by small ones. And this image shows the star strings, the sort of fossil star strings from the, from the galaxy that looped a few times through there before it, it was absorbed into the spiral galaxy. What I think is, and so, and so the pictures interesting scientifically. I think it's very aesthetic. I think it's a good, it's a pretty picture. Okay. It's a good, it's, it's, it's well done. It's technically good. It's aesthetic. This picture represents a discovery. A major discovery by an amateur professional collaboration of star strings around nearby bright galaxies. This is something that couldn't be discovered by large professional telescopes because they're, they don't have, they're not fast, a wide field sort of instruments. So I really, I like this picture. This, this is the perfect astronomy picture of the day climbs the mountain from two sides. It climbs it from the science side and the aesthetic side and reaches that peak. And this is that peak for me. Can you still hear me? Yes. We can. My screen just went blank. Yeah. It says that it went in. So I guess that's a cue. You should stop sharing. I did mention that I was supposed to be the bedtime protector for Jerry. So I should say, Oh, it's like that. We are past time, which, which, you know, but thank you very much. And so that's all for tonight, everyone. Thank you, Jerry, for joining us this evening. And thank you everyone for tuning in. And so our next webinar is, we're going to have to wait just a little bit is Monday, January 10th, when Jessica Taylor from NASA's globe program and Langley Research Center will share with us how you can contribute to NASA science when clouds take over the sky. So, and you can find archives of each of these webinars in the next Sky Network website in the outreach resources section. Each webinar also features additional resources and activities. You can also find all of these webinars archived on the next Sky Network YouTube channel. So keep looking up and we will see all of you next month. And so thank you very much for joining us. And thank you, Jerry. For joining us. You're welcome. Thanks. Thanks for inviting me. Thanks. Yeah, this is a great time. Thank you so much. And of course, been a big fan ever since. Yeah. Beginning of the internet basically. Late 90s for me. I know technically earlier. And I should also mention that, that a few years ago, the, the astronomical society, the Pacific gives out awards. And so a few years ago, I don't remember what year, maybe it was 2015. Like a lot of things happened in 2015, but Jerry and Robert. We received the, what was it Dave, the clunky Roberts award. Robert. Yeah.