Comet ISON

by Chris Simmons

On June 2^nd last year several hundred spectators gathered on the front steps of Battle Creek’s Kingman Museum to observe a once in a lifetime astronomical event.  Wearing special solar viewing glasses they, along with millions of others around the world, were treated to the spectacle of the planet Venus moving across the face of the sun.  This “Transit of Venus” will not occur again until 2117.  But if you missed it don’t worry there are always plenty of other once-in-a-lifetime celestial wonders coming along.  One of those many even happen later this year.

In 2012 astronomers discovered a comet dubbed C/2012 S1 (ISON) on a trajectory heading toward the inner solar system.  Comets are actually a common occurrence and sometimes can be rather spectacular.  You might remember Halley’s Comet, which last passed by in 1986 or the even more impressive Hale-Bopp in 1995.  But ISON has the potential to be the most brilliant comet in several hundred years, maybe even rivaling the Great Comet of 1680.

Comets are primarily composed of rock, ice and dust.  They come from a region of the solar system called the Kuiper Belt or even further out in the hypothesized Oort Cloud, both of which are many times further out than the orbit of the most distant major planet Neptune.   They range in size from a few hundred feet up to many miles in diameter.  Occasionally one of these objects is perturbed, perhaps by the gas giant planet Jupiter, sending it on a path toward the sun.  They typically have a very elliptical orbits angled high above or below the ecliptic plane of our solar system.  Their orbits can take from dozens up to thousands or even millions of years to complete.  Halley’s Comet only comes around approximately every 75 Years while ISON is estimated to have been traveling toward us for several thousand years.

As the comets approach the sun they begin to heat up and water ice and other volatile compounds begin to vaporize from their surface.  This forms the distinctive tail called a coma that we can sometimes see from Earth.  ISON is special because is a sungrazer comet, which means its trajectory will bring it very close to the sun.  In fact it is expected to come as close as 680,000 miles from the sun.   If estimates are correct ISON could be as bright as or brighter than the full moon around Thanksgiving.  It may be so bright that it is even be visible during the day! 

If you are interested in staying up to date on exciting astronomical events like Comet ISON and others please visit Kingman Museum.  Planetarium programs schedules can be found at kingmanmuseum.org or “Like” their Facebook page at facebook.com/kingmanmuseum for updates.

 

March is here and spring is just around the corner.  We will soon be saying goodbye to some of our favorite winter constellations, but there are still many great opportunities to view these easily identifiable groups of stars.   Also March will offer excellent opportunities to view three planets in both the early evening and morning skies.

The best time viewing is usually at least an hour after sunset to an hour before sunrise.  Sunset in Battle Creek is at 6:31 PM on March 1st and will shift ahead one hour on the 10^th due to the return to Daylight Saving Time.  By the end of March our sunset will be all the way to 8:06 PM!  Sunrise starts the month off at 7:16 AM and will be at 7:25 AM by month’s end.

The moon will be new on March 11^th and our next full moon, dubbed the “Worm Moon”, will be on March 27^th.

The zodiac constellations Gemini and Cancer will dominate our early evening skies.  Gemini is easily identifiable by its twin stars Castor and Pollox.  Unfortunately the stars in Cancer are the faintest in the entire zodiac and may be difficult to view in town with light pollution.  Orion, with its distinctive belt of three stars, is one of the easiest constellations to identify.  It is gradually moving west but can still be found high on the horizon.  Follow the belt straight up to Aldeberan, the orange bulls eye of Taurus, and keep going to find the beautiful seven sisters of the Pleiades.  Follow the belt down to Canis Major and its bright star Sirius.   See if you can find the Winter Triangle, an almost equilateral triangle, made by Sirius, Betelguese in Orion, and Procyon in Canis Minor.  These are three of the top ten brightest stars visible in the Northern Hemisphere.

The planet Jupiter is still very bright near Taurus.  It was in opposition, or closest to the Earth, in December.  We are now moving moving away from Jupiter in our orbit around the sun, but will still be very visible for the next few months as it gradually moves to the west each night.  Saturn rises around 11 PM along with Libra and is visible through sunrise.  Mercury can still be seen very low on western horizon at twilight but will be gone by the early week.  Venus and Mars are both currently obscured by the sun.

If you want to learn more about the stars and planets please visit us at Kingman Museum.  The planetarium features two different shows each Saturday and Sunday afternoon that include a star talk with opportunities for question and answer.  Please visit kingmanmuseum.org for more information or “Like” or Facebook page at facebook.com/KingmanMuseum for updates on programs and special events.