The Hubble eXtreme Deep Field

New Hubble Image Takes Us To The Brink Of The Big Bang

The Hubble eXtreme Deep Field picture was made over 10 years from time exposures totaling 2 million seconds or 23 days. It shows about 5,500 galaxies in a patch of sky less than one-tenth the size of the full moon. Click for larger version. Credit: NASA, ESA, G. Illingworth, D. Magee, and P. Oesch (University of California, Santa Cruz), R. Bouwens (Leiden University), and the HUDF09 Team

Hubble sweeps us off our feet again. Using the orbiting 94-inch telescope astronomers have taken the deepest photo of the universe yet. They’re calling it the Hubble Xtreme Deep Field or XDF. It’s based on the older Ultra Deep Field picture made in 2003-2004 of a tiny patch of sky southwest of Orion in the constellation Fornax the Furnace measuring 3 arc minutes or one-tenth the size of the full moon. That picture took 11 1/2 days to expose (1 million seconds) and recorded light from galaxies only a stone’s throw from the Big Bang.

This new image drills into the original ultra deep field, adding another million seconds of exposure time and squeezing even more galaxies from a smaller 2.3 x 2 arc minute peephole. And yes, it takes our cosmic gaze back another 200 million years.

Illustration showing the size of the piece of sky compared to the moon photographed over 10 years by the Hubble Space Telescope. The patch measures 2.3 x 2 arc minutes. Credit: NASA, ESA

The faintest galaxies in the photo are ten billion times fainter than the dimmest star the human eye can see. For those familiar with star magnitudes, a measure of celestial brightness, the picture reaches down to magnitude 31. The picture resembles a sandwich piled high with slice upon slice of time, sampling relatively nearby space as well as the most distant recess of the universe we’ve seen yet.

Some of the galaxies are so far away we see them when the universe was less than 5% of its current age.

See all those tiny blue “stars” peppering the image? They’re young, small galaxies – seeds as it were – that later merged with similar small galaxies to build the stately spiral and monster elliptical galaxies we see in the current era. The blue color comes from fresh generations of blazingly hot blue stars formed in the violence of collision and subsequent star birth.

This image separates out the Hubble eXtreme Deep Field by the distances of objects within it. The galaxies are at vastly different distances from each even though they all appear close together in the XDF photo because they lie along the same line of sight. This illustration breaks down the view into three zones. Credit: NASA/ESA

The large, fuzzy red galaxies are what’s left of collisions between earlier galaxies that failed to ignite new star formation. Their color tells us that their stars are aging. There’s even a smattering of beautiful spiral galaxies similar to our own Milky Way. The farthest objects are 13.2 billion light years away and formed 450 million years after the origin of the univers in the Big Bang.

Closeup of a small section of the XDF with the galaxy UDFj-39546284, candidate for the most distant galaxy yet discovered. We see it as it was 13.2 billion years ago. It’s a small object packed with blue stars. Credit: NASA/ESA


A few days ago we looked backward in time through the lens of a huge boulder dropped by a glacier 10,000 years ago. Hubble transports us to a time when Earth was still an unrealized possibility.

8 Responses

  1. Sebastien

    This is fascinating. Could have Hubble pointed to any direction and see so old galaxies? Or is this more in certain directions that Hubble can find those early galaxies?

    1. astrobob

      Hi Sebastien,
      The answer is YES! Hubble picked that particular spot only because it’s relatively devoid of intervening Milky Way stars and dust and points straight out of the galaxy rather through its busy, dusty plane. There’s also no contamination from the zodiacal light (solar system dust). Outside of that, that particular spot is essentially random, so yes, Hubble would get similar results pointed anywhere if you could remove the foreground dust, etc.

  2. Mike

    Unless I am mistaken the big bang happened at one point in “space” right? Wouldn’t that mean that there could only be one point that we would look back to, to actually see back in time. I am guessing we do know the general direction of the big bang “point”, by the direction we “galaxy/galaxy group” are traveling.

    But how can they know they are looking at that point and not to the side of that point and past it? I ask with the idea that the big bang exploded in every direction and not just in one direction. I wish I could use my hands to explain that, sorry if it’s a confusing question.

    (One example would be; Points in space A – B – C. Big bang is “B”, we are “C” and in our effort to look at “B” we miss it and are looking at “A”).

    1. astrobob

      The Big Bang always poses problems trying to visualize. The key problem is the name – BIG BANG. There wasn’t an explosion IN space, but an explosion OF space. There was no center with particles blasting off in every direction like a conventional explosion. The universe 13.7 billion years ago was the entirety of space – everything! We’re still in the same expanding space today, and it’s space without a center and no preferred direction of movement except outward. To help, think of the expanding surface of a balloon (ignore the center). If you use a marker to put dots on the balloon and then blow it up, the dots will all appear to move away from one another. No matter which dot you pick, from that dot’s perspective, all the other dots are expanding away from it. This balloon surface is a decent 2D representation of our 3D universe – a centerless entity where galaxies are moving away from one another, not because of their own velocity, but because the space between them is expanding. Pretty weird, eh?

  3. Mike

    That is very weird. So can they just point Hubble where ever they think they’ll get a clean shot, avoiding dust, etc and they’ll be looking towards some of the older “stuff”?

    Wow, hmm, as I try to ask questions I realize I don’t fully get it yet. I’l have to think more about it.

    1. astrobob

      Yes. If the entire sky were Milky Way and cosmic dust-free, Hubble would dig up thousands of galaxies in every tiny niche it pointed. Of course every time you look at the sky, you also look back in time. Generally, the fainter the stars you see, the farther away. You can get out several thousands of light years with the naked eye (for stars). The farthest thing most of us can see is the Andromeda Galaxy at over 2 million light years away.

  4. MBZ

    Spectacular. And on the same day Curiosity finds a stream bed.
    Hope you know I’m kidding about that sweater. My spousal unit has one in much weirder colors.
    We are Boomers. Fashion, unhinged 😉

    1. astrobob

      Yes, it’s a busy week! Can barely keep up. Oh, and I love the kidding. That was pretty funny – I never looked at my striped sweater that way before. Your description was perfect.

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