A Thanksgiving visitor from the Oort Cloud

Wednesday, November 25, 2015

Nothing gets the heart of an astronomer beating faster than the prospect of seeing a comet, a visitor from the Oort Cloud (or Kuiper Belt), that vast reservoir of icy bodies out beyond the orbit of Pluto and extending perhaps one-quarter of the way to the nearest star.

And we will have just such an opportunity starting just after Thanksgiving and extending into the early part of January. That could also be the extra incentive for getting that new telescope for Christmas.

A comet is a cold, icy object from the outer regions of our solar system made up of frozen gas, frozen water, and rock--the rocky material is probably more akin to gravel.

As it travels inward, heat from the Sun begins to warm the cometary body and the frozen gases begins to sublimate (turn back into a gas), giving the comet its distinctive tail.

The water-ice begins to melt causing the rocky/gravel-like material to fall off leaving a trail that will turn into meteors if Earth happens to cross the path at a later time.

About this time sunlight illuminates the sublimated gas and melted water giving the comet its distinctive tail which cause us to go all aflutter.

Now, what about this critter. It is called Comet Catalina--or C/2013 US 10 in astronomical parlance--and was discovered by the Catalina Sky Survey on December 31st, 2013 when it was just a bright, moving dot against the background stars (about eight times the Earth/Sun distance away).

As for what it will do? Well, that -- as they say -- is the 64 million dollar question. Comets are notorious for being unpredictable, just like the meteor showers produced by their passing. Astronomers can always guess, but that is just about what it is -- a guess.

As for our friend, C/2013 US 10, there are no grand hopes of a Hale-Bopp or Wild 2, but it could reach naked-eye visibility and will certainly be putting on a nice show for the binocular or telescope-equipped observer.

Now for the bad news, it will be an early morning object for its entire trip into northern skies, generally about an hour before local sunrise; and since the Sun is not rising until almost 7:00 am, that shouldn't be too difficult.

Okay, where do we look? Lets start on Thanksgiving morning, Nov. 26, looking northeast between 5:30 and 6:00 am MST. The comet is expected to be at almost fifth magnitude which will put it within range of naked-eye visibility.

However, if not, then scan the area about 10 degrees above the horizon for a fuzzy blob that might have a small tail. If you need help look up. Draw a line from Jupiter, through Mars, on down through Venus and it will lead you right to the comet.

If you find the comet, don't expect to come back the next morning and look for it in the same place--comets move you know, about a degree per day (the moon is one-half a degree wide). Comet Catalina is moving upwards and slightly left.

Just keep in mind that on Jan. 1, it will be very close to the bright star Arcturus in Bootes, so look along a line leading in that direction. It will eventually move just below the Big Dipper, just to give you an idea of where it is going.

Good luck, and happy hunting. If you locate and observe the comet, drop me an e-mail at thestargeezer@gmail.com and let me know what you saw.