Comet Snowball near Mars
A comet the size of a small mountain is about to skim past
Mars, and NASA hopes its spacecraft will be able to photograph the
once-in-a-million-years encounter. The comet, known as Siding Spring (C/2013
A1), is set to hurtle past Mars at a close distance of about 141,600
kilometeres. The closest pass is expected to happen on Monday at 4.27 am AEDT. Astronomers
do not expect it will come any where near colliding with Mars, but they do hope
it will be close enough to reveal clues about the origins of the solar system. That
is because the comet is believed to have originated billions of years ago in
the Oort Cloud, a distant region of space at the outskirts of the solar system.
The comet is flying through space at a breakneck speed of 200,000 kilometres
per hour. Another interesting thing about the comet, about a mile wide in
diameter, is that it is only about as solid as a pile of talcum powder.