On Oct. 1 of this year, the much awaited Comet ISON is due to pass 6.5 million miles (10.5 million km) from Mars on its way toward a grazing encounter with the sun in November. That rendezvous is close enough in its own right to be categorized as exceptional and yet, Siding Spring will approach about 100 times closer.
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Add CommentIf it is going to hit better start booking your flights early for Australia to get a good view of the fireworks.
Reply | Report Abuse | Link to thisIt should be visible in broad daylight and almost like a 2nd sun for a few moments.
20 billion megatons of explosive power would be an awesome sight.
Crater estimates vary but the typical rule of thumb is 10 times it's diameter for the crater size (so ~300 miles) and 5% of it's diameter for it's depth (so ~ 1.5 miles).
But it could be even larger and deeper as we just don't know how solid either Mars or the Comet is and the angle of incidence.
Probably the scariest thing is if it hits one of Mars moons as that could be disastrous for Earth if it hits to the side of Mars instead of in front of Mars when plowing into one of it's Moons (which would be pulverized).
Mars moons are about 15 miles in diameter (Phobos) and about 8 miles in diameter (Deimos).
So if that were to happen we could see even more debris heading towards the orbit of Earth in about 5 to 6 months as the Earth swings around the Sun into their paths.
That's not a pretty thought.
This could be a fantastic opportunity to observe naturally a process which has been suggested as the basis for terraforming. The introduction of an energy equivalent of 2x10 to the tenth power megatons would have profound local and possibly global warming effects, especially if located at one of the poles. Carbon dioxide and water vapour could be released in prodigious quantities with a consequent effect on both atmospheric pressure and ambient temperature. It is even possible a tipping point would be reached where a runaway greenhouse effect would occur with each release causing a greater release until the reserviors are depleted.
Reply | Report Abuse | Link to thisWow. Keep us updated. Can the rover camera's be put into a position to view the (hopefully) fly past?
Reply | Report Abuse | Link to this"...could be disastrous for Earth..."
Reply | Report Abuse | Link to thisNo; even if the astronomically unlikely scenario you describe were to occur, the orbits are too different, and the distances are too great. The "impact" to Earth (pardon the pun) will be somewhere between too little to matter, and not enough to measure.
You need to keep your Comet Siding Springs straight. The one in the picture above has nothing to do with the story - it passed Earth at 1.2 astronomical units in 2009, and appears to have disintegrated. http://www.gizmag.com/comet-c2013-a1-mars/26472/ would be a good place to find out more.
Reply | Report Abuse | Link to thisCan we try and throw it into Mars? I think we should get some real world practice in before our species' actual survival depends on theoretical techniques.
Reply | Report Abuse | Link to thisHow could it release water vapour from Mars if there isn't any water there?
Reply | Report Abuse | Link to thisBut if it did, could it start off some form of primitive life, or help any already there?
Humans had better not be up there when the comet arrives!
First Jupiter (Shoemaker Levy), then Mars (Siding Spring), next Earth (Lord Voldemort) - Venus and Mercury to come yet!
Reply | Report Abuse | Link to thisThere is plenty of water on Mars, it has water ice caps for example. It's just all frozen at the surface. Look up the Mars Phoenix lander that dug up some of it:
Reply | Report Abuse | Link to thishttp://en.wikipedia.org/wiki/Phoenix_Spacecraft#Presence_of_shallow_subsurface_water_ice
"Teslagirl: "The introduction of an energy equivalent of 2x10 to the tenth power megatons ..."
Reply | Report Abuse | Link to thisThat refers to megatons of TNT, right, eqivalent to 2x10 to the sixteenth "tons"? But of course even at the speed TNT explodes, in that volume, I think the energy would be somewhat dissipated over time.
How many ergs in a megaton? Wouldn't it be good if we translated it into something more related to ergs?
Better, how about we state such big numbers in the somewhat commonly used abreviation, 2E16 megtons in this case?
Better still, how about stating that as 20T5 , 20 times one thousand to the tenth power, a model for even bigger numbers?
If the comet gets close enough to shed matter that ends up on Mars, that may give usable water for future expeditions (if any) to Mars. I suppose it would depend on cometary composition. If it hits Mars it may cause a dust cloud that takes years to settle. I'm also curious as to if Mars will alter the cometary trajectory or impart addition speed or bleed off speed.
Reply | Report Abuse | Link to thisNot true. Phoenix lander found extensive water ice just a centimeter or so below the surface. The northern desert it landed in was a huge skating rink covered with a thin layer of dust. According to Carnegie Institution for Science, Mars has as much water inside the planet as does the Earth. That's a lot of water.
Reply | Report Abuse | Link to thisI prefer Joules.
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