Wednesday, September 11, 2013

Most Photographed in the Universe

Is it Justin Beiber, Miley Cyrus, perhaps President Obama. Nope. It is the comet ISON.

Thanksgiving is the day for the people of earth to catch her pass near the Sun, but where is she now? She is scheduled to make her pass of Mars at the end of this month. Already there are telescopes trained on her though at that time it will be expanded to include the HiRise of the Mars Reconnaissance Orbiter. It is possible that Curiosity may get a peek at ISON, but the HiRise – a powerful telescope meant to take pictures of the Martian surface, if turned toward ISON and should be able to detact the comet's atmosphere and tail.

But if not a total of 16 NASA spacecraft will be watching. NASA also hopes to have every telescope on Earth, or at least most of them taking in the event. The MRO satellite is set to take observations of the comet on Sept. 29and Oct. 1 and 2 and other than the cool factor, the observations could help researchers prepare for a comet that is set to fly even closer to Mars in October 2014.

To properly prepare you for conversations on those days, let me review the Comet life-cycle. Comets, like most other things of the universe, have an orbit. These orbits vary and some are not bound by our Sun but have an orbit out of the solar system. ISON is from the Oort cloud and its trajectory is somewhat parabolic which would suggest it was actually brand-new. It will pass the Sun at a distance of ~1,100,000 kilometers/68,000 miles and poses no danger to Earth though may give us a great show! But I digress.

The next stage in a comets life cycle is extinction. A comet has a tail, this tail is actually made up of a debris field of ice and dust. Every time they make a pass of the Sun, a comet loses a lot of its ice. This quite obviously depends on how close to the Sun it goes. Eventually the comets can lose all their ices and then that awesome sight becomes an inactive asteroid. There is also the break-up phase which some go through, losing all their ices, breaking up and dissipating into clouds of dust.

Another way that some comets come to an end is in colliding with planets/moons. Many of the impact craters we see around the solar system were created by such impacts.

Some factoid on comets are:

·        In history, comets have been recorded as omens of doom. Roman Emperor Nero believed the arrival of a comet foretold his assassination and had every one of his successors killed.

·.       Halley's Comet streaks by Earth every 76 years, and astronomers studied it up close when it last appeared in 1996. The comet had a potato-shaped nucleus, some 9 miles long, that contained roughly equal parts ice and dust.

·        When passing near the sun, comets can leave a trail of dust behind that creates stunning meteor showers years and even centuries later. The Perseid Meteor Shower occurs annually when Earth passes through the orbit of comet Swift-Tuttle, for example.

·        Currently, there are over 3000 known comets. However, scientists theorize that there may be one billion comets in our solar system.

Great comets are comets that are bright enough to be visible from Earth without a telescope. Approximately one great comet occurs every ten years.

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