See the star-eating comet Monday night 11.19.2007

William Atkins
Monday, 19 November 2007 18:22

Science - Space

Ok, Comet Holmes is not really going to eat a star, but the evening of November 19, 2007, in the western hemisphere, will be a good time to see the comet fly directly in front of the star Mirfak (alpha Persei) and appear to engulf it with its large cloud of dust.        

The star Mirfak is the brightest star in the constellation Perseus. The pair (Comet Holmes and Mirfak) will be seen "intermingling" in the northern sky after sunset. Readers of SpaceWeather.com, who are also going to be watching the event with backyard telescopes, are comparing the skyward event to a “giant space-faring jellyfish gobbling a phosphorescent treat.”

To see a sky map of the event, also go to the SpaceWeather.com website: http://spaceweather.com/.

As mentioned earlier, the comet is not really gobbling up the star. Comet Holmes is less than 200 million miles (320 million kilometers) from the Earth, less than twice the distance of the Sun from the Earth. Star Mirfak, meanwhile, is about 590 light-years away, where one light-year is approximately 5.9 trillion miles (9.5 trillion kilometers)—one light-year is the distance that light travels in vacuum (such as in outer space) over a one Earth-year period of time.

When looking at Comet Holmes, it will appear in the constellation Perseus and above the bright star Capella. With binoculars or a small telescope, it will look like a round fuzzy ball.

Comet 17P/Holmes has mesmerized the public and astronomers over the past month by its sudden expansion overnight, on October 23-24, as it went from a minor looking comet in the sky to brightening by over one million times.

However, it is now fading in the night-sky as it flies away from the Earth and the Sun.

Some astronomers are trying to figure out just why it suddenly expanded in size.

As of November 9, 2007, Comet Holmes is the largest object in the solar system, being even larger than the Sun—although the Sun still retains the distinction of being the most massive object in the solar system. Even though its atmosphere is now larger than the Sun, it will eventually lose much of those particles and have to give up its title as largest solar system object.

Astronomers are not certain why the comet expanded after it got to its closest point to the Sun. Normally, comets will outgas (expel) particles as they approach the Sun and reach its closest point on its orbit about the Sun. However, Comet Holmes expanded six months after this event.
 
Some astronomers think that some of its icy particles (made up of ethane, methane, dry ice, and carbon monoxide) got trapped inside its core. They heated up in the contained volume until they could not do anything else but expand outward due to excess pressures. Thus, it exploded in a very violent manner!

What we are seeing now is the result of that explosion.

So, grab your binoculars and telescopes and see another great show November 19th, of course, only if the sky is clear.

Historically, Comet 17P/Holmes was discovered on November 6, 1892 by Edwin Holmes as he was observing the Andromeda Galaxy.

[NOTE from Author: Yes, I meant to say million, not thousands, on the distance of the Comet away from us. The mistake has been corrected thanks to the reader "Drue".]