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Observing Highlights for 2013 January 5, 2013

Posted by aquillam in Astronomy, Urban Observing.
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Highlights for 2013

Rare and Unusual


Anatomy of a comet.

The most exciting upcoming highlights for the year is the possibility of two naked-eye comets. Although Newton’s laws do a excellent job of telling us when and where a comet will be, it’s almost impossible to tell how bright it will be. Comets are fequently called dirty snowballs for good reason – they are basically made of dirt and ice. The ice is mostly water and carbon dioxide (aka “dry-ice”), which are highly reflective, white ices. The “dirt” is mostly silicates (think sand) and carbon compounds (think coal or corn syrup) and tends to be dark and non-reflective. The mix of materials varies a lot from comet to comet, so its hard to say if any given comet will have a lot of highly reflective ice, or a lot of the dark materials. Also, the way the materials are mixed matters. A comet with a big coma and tails will look much brighter than a comet with a smaller coma and tails. The coma and tails form when the ice sublimates, releasing some of the dirt (officially called dust.) Some comets are more chunky, so instead of forming a big cloud, they form something more like a debris stream. These can make great meteor showers, but they aren’t usually good naked eye comets. So, while astronomers can tell you exactly where to look for these comets, they can’t tell you if you’ll need a telescope.

Comet C/2011 L4 PANSTARRS was discovered in 2011 by the PANSTARRS telescope in Hawaii. This is our first possibly bright comet for the year, and you’ve only got a little over a month to get ready. It will be closest to Earth on March 5, then closest to the Sun on March 10, so start looking for it in late February, but don’t expect much until mid-March. It starts the month of March in Pisces, then moves through Pegasus and Andromeda. In April, it passes near the Andromeda galaxy. For more details, check out http://earthsky.org/space/comet-panstarrs-possibly-visible-to-eye-in-march-2013.

Most amateurs have their hopes pinned on comet Comet C/2012 S1 (ISON.) Already visible to large amateur telescopes (under ideal conditions) last fall, some comet observers predict ISON could become as bright as the full Moon this fall. Perihelion is November 28 (Thanksgiving), but it will probably be too close to the Sun to be visible. Closest approach to Earth will be December 26. It is expected to be visible to backyard telescopes by August or September.


It’s actually a very lucky thing we have two potentially good comets, because there isn’t much else unusual this year. All lunar eclipses are penumbral except one on April 25, which occurs midday in Ann Arbor, and less than 1/60 of the Moon will darken. For those down under, there’s an annular eclipse on May 9 – 10. There is a rare hybrid solar eclipse visible of the Atlantic and Africa on November 3. http://eclipse.gsfc.nasa.gov/eclipse.html

The planets:

Mercury makes brief evening appearances in mid February and early June. With a good map, clear horizon, and a small ‘scope, you might be able to catch in September or early October as it skims the horizon. Mercury starts the year as a morning planet, but quickly fades into the dawn twilight. It reappears in the morning sky in late March, and again at the end of July and early August, when it rises in the ENE an hour before the Sun. It probably makes its best appearance in mid November, when it rises almost 1.5 hours before the Sun.

Venus also starts the year as a morning planet, drifting back toward the Sun. By mid January, it will fade into the dawn twilight and be difficult to see even with a small ‘scope. It will not reappear in the morning skies this year. It appears in the evening skies beginning around mid May. It remains an evening planet for the rest of the year, though it tends to stay somewhat low to the horizon until November.

Mars starts the year barely visible at dusk, setting soon after the Sun, and doesn’t return to the evening skies this year. Start looking for it it in the morning in early July.

Jupiter remains a good evening target through mid May, when it starts getting lost in the evening twilight. It returns to the pre-dawn skies mid July, when it joins Mars.

Look south or west for Saturn in the morning through early May. It reaches opposition on April 28, which means it becomes a good evening planet in early May and remains that way until mid October. Looks for it to return to the morning skies in mid November.

There’s a nice twilight conjunction of Mercury, Venus and Jupiter on May 26 at sunset. A small telescope will probably be necessary for Mercury and Jupiter. I’m sure there are other nice conjunctions this year, but I’ll spot them when I do the slightly more detailed monthly posts.

Full Moons in 2013

Observing should be planned around the full Moon, since short shadows on the Moon make it look rather featureless, and painfully bright, and it washes out detail in many other objects. The two weeks before a full Moon are usually good weeks for observing the Moon in the evening and deep sky objects in the morning, and the two weeks after it are a good time to observe deep sky objects in the evening and the Moon in the morning. The night of a full Moon and a couple days on either side are generally not good for observing anything except bright planets.

Times are UT (that’s EST -5, EDST -4), and are given mostly because I had them. http://aa.usno.navy.mil/data/docs/MoonPhase.php

  • January 27, 4:38 AM
  • February 25, 8:26 PM
  • March 27, 9:28 AM
  • April 25, 7:58 PM
  • May 25, 4:26 AM
  • June 23, 11:32 AM
  • July 22, 2:15 PM
  • August 21, 1:46 AM
  • September 19, 11:14 AM
  • October 18, 11:38 PM
  • November 17, 3:16 PM
  • December 17,  9:28 AM


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