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Artist's concept of comet Siding Spring passing Mars- Glen Nagle |
According to latest observations indicate that the comet will pass within 186,000 miles (300,000 kilometers) of Mars on Oct. 19, 2014.
The NEO Program Office's current estimate based on observations through March 1, 2013, has it passing about 31,000 miles (50,000 kilometers) from the Red Planet's surface. That distance is about two-and-a-half times that of the orbit of outermost moon, Deimos.
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| Comet 2013 A1 (Siding Spring) through the inner solar system. On Oct. 19, 2014. |
According to Elenin: "On the 19th October 2014, the comet might reach apparent magnitude of -8 to -8.5, as seen from Mars!” (This would make the comet 15 to 25 times brighter than Venus). "Perhaps it will be possible to acquire high-resolution images from the Mars Reconnaissance Orbiter (MRO)," he added.
Image Credit: NASA/JPL
Then there may be collusion with Mars or there maybe no collusion !
Moving at 35 miles (56 km) per second, such a collision could create an impact crater on Mars up to ten times the diameter of the comet's nucleus and up to 1.25 miles (2 km) deep, with an energy equivalent up to of 2 x 10^10 megatons!
This is the second closest passing comet to Mars. There may be collusion or there may not But the comet is going to pass really closer to mars
Here more info by By Emily Lakdawalla
This is an interesting case to consider. As you already know, the uncertainty in the orbit does allow for an impact, but there is a lot of wiggle room and, for the moment, this case seems unlikely. However, you make a good point; we should consider if the dust could produce a Martian meteor shower. This scenario reminds me of the occasional meteor storms that occur on Earth after a close comet flyby. One that comes to mind are the meteor storm of Comet 21P/Giacobinni-Zinner in 1933 and 1946, when Earth passed the orbit of the comet shortly after the comet had been there. Thousands of meteors per hour were observed in these events.
With this in mind, I examined the distance between Mars and the comet's tail. The comet is currently predicted to pass Mars at a distance of about 100,000 km. Unfortunately, the comet's tail is more or less pointed away from Mars during the close encounter. In other words, it doesn't really come any closer to Mars than this distance.
So, can the coma be ~100,000 km in size? If small dust grains are ejected at a few tens of m/s, it only needs to be ejected a month or two before the closest approach to Mars to travel this distance in the absence of radiation pressure. But accounting for radiation pressure any dust this old will be pushed far down the tail, and since the tail is pointed away from Mars... no meteors. I ran a short 3D simulation that agrees with this assessment. The coma has already evolved into a tail well before it travels 100,000 km.
You were also asking about millimeter-sized grains. These will be ejected with lower velocities, perhaps only a meter per second or less, and would take more than a year to travel 100,000 km from the comet in the absence of radiation pressure. Again, once we consider radiation pressure, and giving it a year to act on the dust, even grains this large will be pushed quite far down the tail.
So, in short, I'm not predicting anything spectacular for Mars, but I hope I'm wrong! If the closest approach distance decreases significantly, then we may have to revisit this experiment with a more careful treatment.
Above Source : http://www.planetary.org