Astronomy 101, Part II: Comets

Comets are basically just big balls of frozen water, dirt, and gasses. They come whizzing into the inner solar system from out beyond the orbit of Pluto, make a trip around the sun and head back out to where they came from -- generally.

In ancient times they were thought to be bringers of bad news. You know, kings dying, catastrophe and other sorts of bad news.

What's more, they would often take hundreds of thousands of years to do it; the trip each way that is.

At present there are two comets coming in from the cold of the outer solar system for their trip around the sun.

The first, Comet PanSTARRS, C/2011 L4, will make its appearance in the western sky toward the end of this week and beginning of next week.

PanSTARRS stands for Panoramic Survey Telescope and Rapid Response System. The comet should be visible in the western sky just after sunset between March 8-10.

Its closest approach to Earth was on March 5, and closest approach to the sun on March 10.

When first discovered, astronomers were saying it should be a very bright comet, but such has not been the case. It has been visible to viewers in the southern hemisphere for a couple of weeks, but has not produced the brightness they had hoped for.

To find the comet go outside starting on the evening of March fifth about a half-hour after sunset and look west. You will need a very clear, uncluttered horizon because the comet will not be very far above the horizon. It will set by 7 p.m.

Probably the best time to look for the "faint fuzzy" will be on Tuesday, March 12, when it will be above the horizon longer, and will be near two other objects which should help with locating it.

On that date the comet, a very slender one-day old moon, and the planet Uranus will all be within the same binocular field of view.

If it is still bright enough, another good viewing opportunity will be during the first week of April (April 1-6) when the comet will be very close to the Andromeda Galaxy, both will be in the same field of binocular view on those dates.

The other comet is Comet ISON C/2012 S1 (International Scientific Optical Network) which will make an appearance for us in the northern hemisphere in November.

Again, astronomers have high hopes for this one, saying it could be bright enough to be seen in the daytime.

Analysis of its orbit shows it has taken perhaps more than million years to come in from the outer solar system and is in all probability not a periodic comet. That means it won't be back in our lifetime.

Astronomers believe when it rounds the sun, its orbit will be shortened to 110,000 years.

So, if you have never seen a comet, now is your opportunity to do so.

SKY WATCH: New moon, March 11. March 12, Comet PanSTARRS, Uranus, and the moon all together in the west. Look at about 7:30 p.m. MDT. Daylight Savings Time starts Sunday, March 10 so "Spring" ahead. Speaking of spring, it will arrive in two weeks.

NEXT WEEK: More astronomical blathering.