11 October 2013

Comet C/2012 S1 - Comet ISON Approaches

Comet C/2012 S1
Comets are beautiful and engaging to watch, gracefully floating across the night sky, arriving unexpected and sometimes surprising us with an extraordinary show. Some comets are regular visitors to Earth ("short period comets" such as Halley's Comet) and are very predictable, but others arrive from the vast reaches of the outer Solar System (the Oort Cloud) and make only one pass through our neighborhood, never to be seen again. Comet C/2012 S1, better known as Comet ISON, is of the latter category, packing enough ice and mass to become 'the comet of the century' when it has a rendezvous with the Sun in late November. Predictions of spectacular comets sometimes miss (anyone remember Comet Kohoutek?) so we always try to plan for comets with lowered expectations and hope to be pleasantly surprised.

Finding Comet ISON
Comet ISON passed near Mars a few weeks ago and is on a near-collision course with the Sun. A comet with a close encounter like this is called a Sungrazing Comet -- Comet ISON will pass within a solar diameter of the Sun, so close that it might not survive the trip back out of the Solar System. If it does, however, it is expected to have a beautiful tail and could be quite a spectacle. We have to watch and see.

This coming week provides an opportunity to spot Comet ISON as it appears in the morning sky, when it will be in close alignment with Mars and the bright star Regulus. Look to the east before sunrise (around 5:00 or 6:00 am) and use some kind of optical aid such as binoculars, and you'll have a nice view of the comet. I'll be out each morning to take a look, and will update the blog with news.

Images courtesy of NASA/Hubble, and EarthSky.org.

Update October 15: have tried two mornings in a row to spot ISON with binoculars from San Francisco, but have not yet found it. Either it is quite tiny, too faint, the skies here are too light polluted, or all of the above. Will continue to try the remainder of this week.

1 comment:

Anonymous said...

This past Monday morning I looked just above the line from Regulus to Mars, continuing about 30% of that distance further and could not spot it with my 5" scope (f/5) and a 25mm eyepiece. it was about 4:30 a.m. and I had no trouble seeing Mars or Regulus.

What is its apparent magnitude at this point (3rd week of October)?

I have only had a scope for about 5 weeks (a handful of observing experiences since with mixed success supported a couple of times by "regulars" though not on this morning.

Any hints?