A pristine comet is heading towards Mars, approaching closer than one third of the distance from the Earth to the Moon. Astronomers are preparing for an exciting astronomical event that occurs just once in a million years.
At a speed of 202,000 kph, the Siding Spring comet – a mountain-sized ice ball, accompanied by a gigantic trail of dust – will miss the red planet by just 140,000 km at 18:27 GMT on Sunday. Named after the Australian observatory where it was discovered in 2013, the comet has a nucleus, or icy core, with a diameter estimated at 0.8 to 8 km.
The closest observers of this historic event will be three NASA robotic explorers, India’s Mangalyaan spacecraft and Europe’s Mars Express. Using a “duck and cover” strategy after the observations, the orbiters have been repurposed to hide for about 20 minutes behind the planet’s body. This will protect them against the comet’s potentially harmful trail, which is as long as from here to the moon and is expected to engulf the entire planet.
However, the Opportunity and Curiosity rovers are set to get the best view, if no dust storm on Mars obscures the planet’s sky.
“We certainly have fingers crossed for the first images of a comet from the surface of another world,” said Kelly Fast, NASA program scientist, adding “This is kind of a dusty season on Mars, too, and so the dust is going to make the comet even less bright.”
Astronomers are anticipating the encounter and will be monitoring via Earth-based and space telescopes, such as the Hubble Space Telescope. “We’re getting ready for a spectacular set of observations,” said Jim Green, head of NASA’s planetary science division.
South Africa and Australia are topping the list of best places for viewing via binoculars or telescope. In the Northern Hemisphere, it will be quite difficult to catch a glimpse of the comet.
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