Jimmy Westlake’s top 10 celestial events for 2013
December 29, 2012
Steamboat Springs — 2013 will be the Year of the Comet. Not one, but two potentially bright comets are headed our way: one in early spring and one in late fall. If they live up to their potential, Comet PanSTARRS and Comet ISON will be the real headline grabbers in 2013, but there are plenty of bright planets and showers of shooting stars to keep us looking up all year long.
Here are my choices for the top 10 celestial events for 2013 in chronological order. No optical aid is required to view and enjoy these events, though binoculars or a small telescope will enhance the view in some cases.
Jan. 21: The moon meets Jupiter
When the sun sets Jan. 21, step outside and marvel at the moon and the brilliant planet Jupiter sitting side by side. The two will be less than a degree apart for most of the early evening. In fact, when the two are at their closest at about 8:30 p.m., you barely could squeeze another moon between them.
This close encounter provides a perfect opportunity to observe the moon's orbital motion in progress. Catch the two early in the evening and then step out and look again every hour. Because the moon moves its own diameter eastward each hour as it orbits Earth, you can watch as it slowly passes the giant planet.
Aim your binoculars toward the pair to get a better view, and you also might glimpse two of Jupiter's four giant moons, Ganymede and Callisto, looking like little stars on either side of the planet. With a telescope, you also should be able to catch sight of the remaining two giant moons, Io and Europa, much closer to Jupiter. The bright orange star off to the moon's lower left is Aldebaran, the eye of Taurus the Bull. The Pleiades star cluster twinkles to the Moon's upper right.
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March 13: Comet PanSTARRS and the crescent moon
Comet C/2011 L4, or Comet PanSTARRS for short (named for the Panoramic Survey Telescope and Rapid Response System that discovered it), has the potential to become a bright, naked-eye spectacle in March.
Because comets are made mostly of ice, the closer a comet comes to the sun, the more the icy stuff vaporizes and the brighter the comet can get as it puffs up. Comet PanSTARRS will pass within 28 million miles of the hot solar furnace March 10 — that's closer than the scalding-hot planet Mercury gets to the sun.
Then, it heads north into our early-evening sky. On the evening of March 13, Comet PanSTARRS will appear 10 degrees below the thin crescent moon after sunset. Start scanning the western horizon early because, by 9:30 p.m., the comet and the moon will have set. The prime time will be 8 to 8:30 p.m. If the comet grows a long tail, it might extend up and behind the moon, but no one accurately can predict the behavior of a comet weeks before it arrives. Comet PanSTARRS could crumble and fizzle out as it rounds the sun, or it could hold together and become as bright as the planet Venus.
It is their unpredictable nature that makes comets so fun to watch. So have fun, because Comet PanSTARRS won't be back for 110,000 years.
April 28: Saturn at opposition
Once every 378 days, the Earth gains a lap on the sluggish planet Saturn and passes directly between Saturn and the sun, placing the two planets as close together as possible. This alignment of worlds is called opposition. When Saturn reaches opposition April 28, it will be 820-million miles from Earth, its closest point in 2013. Saturn will rise in the eastern sky at sunset and shine brightly in our sky all night long near the border between the constellations of Libra and Virgo, not far from Virgo's brightest star, Spica.
A telescope of any size aimed at Saturn will reveal the beautiful system of rings encircling its equator and the largest of its 62 moons, planet-size Titan. After presenting themselves edgewise to Earth in 2009 and briefly disappearing from view, the rings have been opening up to us again in all their splendor. So point that telescope at Saturn this April. You won't believe your eyes.
May 26: Venus, Jupiter and Mercury cluster in evening sky
Because the five naked-eye planets are among the brightest objects visible in our earthly sky, groupings of the planets often are spectacular. During the last week of May, three of those planets — Venus, Jupiter and Mercury — will cluster in our evening sky and put on quite a show.
On the evening of May 26, the three planets will form a tight equilateral triangle, about 2 degrees on each side. You easily can hide the trio of planets behind your thumb held at arm's length. The show actually begins May 24, when Venus and Mercury pass only 1.4 degrees from each other. Then, Mercury and Jupiter appear only 2 degrees apart May 27, and Venus and Jupiter are closest May 28 at only 1 degree apart.
When the two brightest planets appear that close together, it's always a "wow" moment. Of course, the planets aren't really as close together as they seem; they just happen to lie along the same line of sight from Earth, so there is no danger of a collision. Watch for this parade of planets very low in the northwestern sky from 9 to 9:30 p.m. each evening in late May.
June 10: Moon joins planets Venus and Mercury
The solar system's two innermost planets, Mercury and Venus, behave differently than the rest of the planets. Instead of being free to wander all the way around the night sky, they are tethered to the sun, so they seem to swing out from one side of the sun to the other and back again. Consequently, each planet spends a brief time as an "evening star" followed by a brief engagement as a "morning star." The best time to catch each planet is when it is near its greatest angular distance from the sun in our sky, an event called greatest elongation. Even at greatest elongation, Mercury is never more than 28 degrees from the sun and Venus never more than 48 degrees from the sun. Mercury reaches its greatest elongation at 24 degrees east of the sun June 12 while appearing very close to the much-brighter planet Venus in our evening sky.
Catching a glimpse of this unusual double evening star is reason enough to step outside at dusk and gaze skyward, but try to catch it two days earlier, just after sunset June 10. That's the evening that the thin crescent moon joins Mercury and nearby Venus for a striking triple conjunction. Look low in the west-northwest sky at about 9:30 p.m.
August 12: Annual Perseid meteor shower
The August Perseid meteor shower is one of the most reliable of our annual meteor showers. We experience this shower of "falling stars" every Aug. 11 and 12 when the Earth plows head on into the dust swarm left behind by a comet named Swift-Tuttle. If the sky is dark and clear, a single observer usually can count about 90 meteors per hour during the shower's peak before dawn Aug. 12. The Perseids shoot across the sky in brief flurries of two or three with several minutes of calm in between. The meteors will seem to spring from the constellation of Perseus, the Hero, hence the name of this shower.
Perseid meteor watching makes a great family activity. Take the kids and find a dark campground, roll out the sleeping bags and watch the fireworks. See who can count the most meteors or who can spot the brightest one. This August, the five-day old moon will set at about 10:30 p.m., leaving the sky dark for watching dozens of meteors shoot across the sky.
Nov. 1: Venus at greatest elongation
For the last half of 2013, the dazzling planet Venus will be our constant evening companion, the first "star" to pop out after sunset. Venus will pose beside the waxing crescent moon at dusk once each month: June 10, July 10, Aug. 9, Sept. 8, Oct. 7, Nov. 6 and Dec. 5. The Sept. 8 event will be the closest, with Venus and the moon appearing less than 3 degrees apart. Venus will reach its greatest elongation 47 degrees east of the setting sun Nov. 1. On that evening, Venus will set about 2 1/2 hours after the sun. After that date, Venus will start closing the gap between it and the sun as it dives in between the Earth and sun Jan. 11, 2014. At that point, it leaves our evening sky to become our "morning star" for much of 2014.
With a telescope, you can watch the phase of Venus change like a tiny moon from nearly full in June to a thin crescent by December. When it leaves our evening sky at the end of the year, our winter nights will seem very empty, indeed.
Nov. 28: Comet ISON rounds the sun
Move over, Hale-Bopp. There's a new kid in town that might become the brightest comet in our lifetimes. It's C/2012 S1, or Comet ISON (named for the International Scientific Optical Network telescope that found it). Comet ISON is a big, sun-grazing comet that has the potential to outperform any comet in recent history if it survives its dramatic hairpin turn around the sun Nov. 28 to 29. During that sharp turn around the sun, the snowball that is Comet ISON will pass within 700,000 miles of the solar surface. It will be vaporizing at such a prodigious rate that it likely will be visible with the naked eye right beside the sun on the afternoon of Nov. 28. Of course, extreme caution must be used when observing something so close to the sun in the daytime sky.
If Comet ISON survives its close encounter with the sun, Comet ISON then will enter dark skies as it recedes from the sun and might sport a tail that stretches far across our sky. The comet is expected to pass 39 million miles from Earth on Dec. 26. The timing and geometry of the comet's orbit suggest that it could be visible to the unaided eye for many weeks between November 2013 and January 2014. Or, it could be a total flop. I, for one, can't wait to find out!
Dec. 13: annual Geminid meteor shower
The annual Geminid meteor shower seems to be getting stronger each December. First observed in 1862, Geminid meteors spring from our constellation of Gemini, the Twins, and are associated with the asteroid or burned-out comet Phaethon. The 2012 Geminid meteor shower exceeded even the most optimistic predictions as meteors were shooting across the sky at a rate of more than 120 per hour. If that trend continues, the Geminids soon could become our most active annual shower.
In 2013, the nearly full moon definitely will put a crimp in meteor watching, but there will be plenty of bright Geminids that will shine through the moonlight. When the moon does set at about 4:50 a.m. on Dec. 14, there will be about an hour of dark sky just before dawn for the best meteor watching. As an extra bonus, Comet ISON will be up in the eastern sky at about the same time. It's far too early to know how bright it will appear, but it might still be visible to the naked eye in mid-December.
All year: active sun and chance for an auroral storm
Nothing that I have ever observed in nature can top a vivid display of the northern lights. It is a jaw-dropping, knee-wobbling experience. Seeing them from Colorado is uncommon, but not unheard of. The trick is knowing when and where to look.
This year, as the sun ramps up toward its once-per-decade maximum in activity expected in late 2013, our chance of a powerful geomagnetic storm sending auroras our way improves greatly. Auroras tend to cluster around the March and September equinoxes and reach a fever pitch in the hours around midnight, while most folks are snug in their beds, unaware of the spectacle unfolding outside. Get a heads up for auroral activity by making it a daily ritual to visit NASA-sponsored http://www.spaceweather.com. This website provides daily, even hourly, forecasts and alerts for auroral activity around the globe. By keeping abreast of solar storms headed our way, you'll know on which nights to keep a vigil for the northern lights. You even can arrange to receive an automated telephone call in the event of an auroral storm in your area. It doesn't get any sweeter than that! I'm betting that once or twice in 2013, the northern lights will come our way and give you that jaw-dropping, knee-wobbling experience, too.
Professor Jimmy Westlake teaches astronomy and physics at Colorado Mountain College’s Alpine Campus. For a complete list of 2013 celestial events, check out Westlake’s 2013 Cosmic Calendar, which features 12 astrophotographs. Proceeds from calendar sales support Colorado Mountain College's SKY Club.
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