Articles by J. Alex Knoll

Even invisible, it tugs our tides mightily

    Tuesday marks new moon — the first of January’s two Supermoons. What? How can new moon be a Supermoon? The criteria for the relatively new term Supermoon isn’t that we can see it, but rather that the moon, sun and earth are all three aligned in conjunction with the moon’s closest point to earth in its monthly orbit, called perigee. This can happen during both full moon and new moon. There will be six Supermoons in 2015, with January, February and March coinciding with new moon and July, August and September with full moon.
    New or full, a Supermoon can create super tides. The alignment of earth, sun and moon at new and full moon creates a gravitational tug resulting in strong spring tides. High tide is higher than normal, and low tide is lower. A Supermoon’s closer proximity to earth adds to the pull, creating even greater swings in what are called perigean spring tides.
    Look for the nascent crescent moon to reappear low in the west just after sunset Wednesday, with Venus just a few degrees to the moon’s left and Mercury between the moon and the horizon.
    Mercury and Venus were one degree apart last week, but now the innermost planet is sinking back toward the western horizon and the glare of the sun. They are still within three degrees of one another Friday, but by Wednesday the gap will have grown to almost 10 degrees.
    Mars is above and to the left of Venus and Mercury at sunset, visible until 8pm. Monday the red planet appears within 15 arc minutes — one-quarter degree — of distant Neptune in a rare planetary conjunction. At magnitude 8, Neptune demands binoculars or better yet a telescope. Start at Mars and scan above and to the left.
    Keep the binoculars handy, and look for Comet Lovejoy Saturday eight degrees west-southwest of the Pleiades star cluster, high overhead above Taurus the bull after dark.

The sky is awash in the sun’s absence


The Geminid meteors are unique

    Like all meteor showers, the Geminids occur as earth passes through a trail/stream of cosmic dust and detritus. As these bits of rock and ice hit our atmosphere, they burst into flames. While the end results are the same, the source of the Geminids’ debris trail is unique. In every other case, these trails of debris are left by comets orbiting the earth in the same way as the planets. The source of the Geminids, however, is a five-kilometer asteroid, known as 3200 Phaethon, that passes between the sun and Mercury every 1.4 years.
    And where comets orbit the sun with a long tail releasing a trail of flotsam, 3200 Phaethon has no tail but somehow produces a trail of debris anywhere from five to 500 times larger than any spawned of comets. Instead of a tail of its own releasing fragments as it’s heated by the sun, 3200 Phaethon pulls bits of dust and debris into its wake as it travels the solar system in a way astronomers are still trying to explain.
    Many meteor showers have been seen since the dawn of civilization, but not the Geminids. They were first noted in 1862 — simultaneously — by an American and a British astronomer, who each recorded an average of 14 meteors an hour. Year by year, that number grew, even as astronomers searched for the shower’s source. Then in 1983, armed with the Infrared Astronomical Satellite, they found 3200 Phaethon to be the parent of the Geminids. By that time, the shower had grown to an average of 120 meteors an hour under good conditions!
    With clear skies you can see the spawn of 3200 Phaethon anywhere in the dark sky, but all point back to the constellation Gemini.
    While you’re at it, look for Jupiter rising in the east-northeast around 10pm and high in the south come dawn. Saturn rises just ahead of the sun in the east-southeast. And Venus and Mars are both visible after sunset.

When there aren’t 24 hours in a day


Constellation joins moon and Jupiter, hosts meteors

    Jupiter rises in the east-southeast a little before midnight, and by 6am it is almost directly overhead. Early Friday morning it is less than 10 degrees above the last-quarter moon. Saturday the moon is just below Aldebaran, the heart of Leo the lion. Sunday Jupiter, Regulus and the moon form a near-straight line, each roughly 10 degrees apart.
    The following nights, the moon shifts eastward compared to Jupiter and Regulus, until Wednesday a thin crescent rises before dawn with blue-white Spica just three degrees away.
    The waning moon shouldn’t interfere with the peak of this year’s Leonid meteor shower in the wee hours Tuesday morning. With clear, dark skies you may see 15 to 20 meteors in a given hour. The meteors can appear anywhere in the sky, but traced back they appear to emanate from the shower’s namesake, Leo.

The lonely star swims with the fishes

    Mercury is at the tail end of its best pre-dawn appearance of the year. The innermost planet rises in the east-southeast around 5:30 at week’s end and is 10 degrees above the horizon as daybreak approaches. Mercury outshines any nearby stars, but that doesn’t make it easier to spot, but binoculars will help you find it tight against the horizon. Don’t confuse it with Spica a bit higher and to the right or with golden Arcturus much higher and to the left.
    You shouldn’t have any trouble spotting Jupiter before dawn. The gaseous giant rises before midnight and is almost directly overhead before sunrise. The bright star to its lower left is Regulus, the heart of Leo the lion. With Venus hidden behind the sun, only the moon outshines Jupiter in our night skies. You can compare the two between sunset Wednesday and sunrise Thursday the 13th, when the waning gibbous moon is within 10 degrees of Jupiter.
    The only other planet visible is Mars low in the southwest as evening twilight gives way to darkness.
    Early November marks the peak of two meteor showers, the South Taurids November 5-6 and the North Taurids November 11-12. Neither is a prolific shower, and both suffer the moon’s bright glare. But they both have staying power, producing a meteor here, a meteor there for days. Better yet, every now and then these slow movers burst aflame, crossing the sky as fireballs.
    Glance to the south after sunset this time of year and you’re not likely to see much except one bright, blue-white star known as the Lonely One. Fomalhaut appears all the brighter due to the company it keeps. Part of Pisces Austrinus, the Southern Fish, Fomalhaut is the only first-magnitude star amid autumn’s dim, ethereal, water constellations. Only after your eyes have had a chance to adapt to the darkness will you see the creatures within this celestial aquarium: Pisces the fish, Cetus the whale, Aquarius the water carrier, Capricornus the sea goat and Delphinus the dolphin.

Halloween falls right in between

    The Celts of pre-Christan Britain called this cross-quarter day Samhain, celebrating both the end of the harvest and the end of the year. On this night, the veil between the world of the living and the realm of the dead was thought to be especially thin, so people lit bonfires and lanterns from hollowed-out gourds to ward off spirits.
    As Christianity spread, it merged its own holy days with the pagans’ cross-quarter holidays. Imbolc became Candlemas, now better known as Groundhog Day; Beltane gave way to May Day; Lugnasad became Lammas. And Samhain was absorbed into All Saints Day or Hallowmas, marked on November 1, with the night before Hallow’s Eve.
    Now the cross-quarter day coincides with another ritual, setting our clocks back an hour in the return to Standard Time at 2am the first Sunday of November.
    The first week of November provides the best view of Mercury before dawn. The innermost planet reaches greatest elongation November 1, its farthest west of the sun and its highest in our sky. An hour before sunrise, look for it not quite 10 degrees above the east-southeast horizon — roughly the size of your fist at arm’s length. At magnitude –0.6, Mercury is brighter than any nearby star (all but Sirius, in fact), but binoculars may help locate it in the glow of twilight. Don’t confuse the bright planet for Arcturus higher in the east-northeast.
    You shouldn’t have any trouble finding Jupiter. The gaseous giant rises around midnight, and as dawn approaches it is high in the southeast, bluish Regulus and the other stars of Leo the lion stretched out below it.
    Mars is the only planet visible in the evening, shining no brighter than your average star but still a distinct orange-red. Look for it low in the southwest as darkness settles, where it will remain the rest of the year.
    Early November marks the peak of the South Taurid meteor shower. The higher the constellation Taurus, the more meteors you’re likely to see, although the waxing moon will limit you. Still, the Taurids can deliver the occasional fireball.

Even eclipsed, this star blinds

    Try projecting the image through binoculars. Cover one lens and aim the other at the sun, pointing the eyepiece toward the floor or a piece of paper until the sun’s orb appears. Bring it into focus, and voila! You may want to use a tripod, and you can use a small telescope in the same fashion.
    Another option for watching the sun is a pinhole projector, a perennial science project requiring only two sheets of white paper and a pin. Poke a clean round hole in a sheet of paper. With your back to the sun, hold the pierced paper between the sun and the second sheet of paper until you see the sun’s inverted image projected onto it. Increasing the distance between the two sheets enlarges the image but decreases its sharpness. Or you can get more elaborate using the same principles with a box large enough to put over your head to create a viewing chamber.
    Here along Chesapeake Bay, the eclipse begins Thursday at 5pm with the sun low in the west. Alas, it will still be in full swing come sunset at 6:17pm.
    The eclipse won’t be your only chance to put a pinhole projector to use. The sun right now is in the midst of a massive solar storm, resulting in sunspots large enough to see with the protected-but-unaided eye.
    Sunspots start as massive magnetic bursts deep within the sun that migrate to its surface. While highly charged, this energy is cooler than the sun itself, thus appearing darker than surrounding areas. Once to the surface, the energy flares into space in what are called Coronal Mass Ejections, which can wreak havoc on satellites and take down sections of the power grid. Already the International Space Station has turned to face away from the sun to limit the damage from this solar storm.
    Out of all this violence comes beauty, too, in the form of the Northern Lights. So keep a lookout, as a solar storm of this magnitude could make them visible this far south. Learn more at
    The moon returns to view Saturday as a thin crescent very low in the west-southwest. Look to its lower right for Saturn. As the moon waxes into the new week, it shines near the planet Mars.

It’s a crowded solar system

    The only other naked-eye planets visible are Mars and Saturn, low in the western sky in the darkening twilight. Saturn is fast on the heels of the setting sun, while Mars is farther to the east. Don’t confuse Mars for Antares, the red heart of Scorpius and roughly midway between the two planets.
    Mars has a close encounter Sunday, when Comet Siding Spring (C/2013 A1) passes within 82,000 miles of the red planet. For comparison, the moon orbits the earth by almost 240,000 miles, and the closest recorded comet to pass us was in 1770 at 1.4 million miles! While a collision isn’t predicted, the comet’s tail will likely engulf the red planet. Even with binoculars you’ll be hard-pressed to see Comet Siding Spring, but a telescope will reveal it above the red planet.
    We have our own close encounter with a comet — Halley’s Comet, no less — in the form of the annual Orionid meteor shower, which peaks late Tuesday and early Wednesday. The comet hasn’t visited the inner solar system since 1986, but each year at this time earth passes through the trail of debris left behind from its countless orbits around the sun. With the waning crescent moon rising shortly before dawn, you might see from 20 to 25 meteors an hour. They can appear anywhere in the sky, but if you trace back their path they radiate from the constellation Orion.
    The sun and moon have a close encounter of sorts Thursday the 23rd, resulting in a partial solar eclipse in the early evening. Be warned: Gazing upon a solar eclipse can cause blindness, and a partial eclipse is all the more dangerous, so look only with a solar filter.
    Just as it takes a full moon for a lunar eclipse like the one two weeks ago, a solar eclipse coincides with new moon, when it passes between sun and earth, blotting out the sun’s disc — or part of it in the case of this partial eclipse.
    Hereabouts the show begins at 5:52pm, with the greatest point of eclipse coming at 6:08, when one-third of the sun is blocked from view. Alas, the sun sets at 6:17 before the eclipse is over.
    Again, do not attempt to watch the eclipse without protective eyewear; use the coming week to find solar glasses or another proper filter.

Its far side is always dark to us
