The new studies have "upped the odds a lot" that an impact caused the dichotomy, says planetary scientist Walter Kiefer of the Lunar and Planetary Institute in Houston. The next line of evidence, says Kiefer, would be looking for chemical differences in Martian rocks indicating that crust in the dichotomy formed from material deep inside the mantle that welled up after the impact.

The kind of asteroid needed to form the Martian dichotomy would fall in between that size and those of the rocks that formed other large craters, such as the South Pole—Aitken impact basin on the moon and the Hellas Basin in Mars's southern hemisphere, both more than 1,30 miles (2,000 kilometers) wide.

Although Earth's inhabitants still face the threat of deadly asteroid strikes, researchers say that impacts of the magnitude seen in the Martian dichotomy have long since died off, leaving only scars to tell their story.

"The early solar system was a very dangerous place to be," Andrews-Hanna says, "but if we didn't have the impacts, we wouldn't have the planets as we see them today."

7 Comments

1. 1. redfoxone 10:53 PM 6/25/08

   Amazing, how do they come up with this stuff?
   http://www.FireMe.To/udi

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2. 2. Jokunen 12:26 PM 6/28/08

   "both more than 1,30 miles (2,000 kilometers) wide."
   
   Probably this should be 1300 miles, not 130.
   
   -Petri-

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3. 3. Robert Simko 02:28 PM 6/30/08

   Perhaps the impact ripped away much of Mar's atmosphere. Mar's lower mass and gravity would not recapture the atmosphere, the way Earth would. Mars is small, but so is Venus and that planet has a substantial atmosphere.

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4. 4. rcdohare 04:32 AM 7/2/08

   The asteroid size bigger than our moon, from where it came? Is it possible
   that asteroid of that size can come to so closure and does not got impact with other planet such as jupiter,saturn , urenus & Neptune if it is not from
   our solar system .If it is from our solar system than it must be satelite of Mars. Than only it speed before collision was 10km/sec. otherwise it would
   be more than 1,40,000km/hr.
   rcdohare25@yahoo.co.in

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5. 5. Forbidden Planet 11:48 AM 7/2/08

   
   Have they determined the age of the two ?

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6. 6. Stin_nar 10:45 PM 9/15/10

   could it be that we are not the first intelligent life in the solar system and mars was like earth teeming with life until that asteroid came along?

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7. 7. RomanCitizen 02:24 AM 8/4/11

   I think this catastrophe explanation for all kinds of crust formation on the inner planets (Earth, Moon, Mars etc.) is becoming some kind of an obsession for some scientists. I wonder why, when there are much more probable explanation for the formation of the features in question.

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