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Mars Had an Ancient Impact Like Earth

Posted by samzenpus on from the hit-it-hard dept.

quixote9 writes "The BBC reports on a set of Nature articles showing that Mars had an impact about four billion years ago by a huge asteroid. This was about the same time that a much bigger object slammed into the Earth, throwing material into orbit around our infant planet. This material is thought to have coalesced to form the Moon. 'It happened probably right at the end of the formation of the four terrestrial planets — Mercury, Venus, Earth and Mars,' said Craig Agnor, a co-author on the Francis Nimmo study. 'In terms of the process of the planets sweeping up the last bits of debris, this could have been one of the last big bits of debris.' There's a theory that having a big moon is important to the development of life, because the much bigger tides create a bigger intertidal zone, but people used to think having a huge Moon like ours was a once-in-a-universe event."

7 of 167 comments (clear)

  1. Hopefully. by pclminion · · Score: 4, Interesting

    people used to think having a huge Moon like ours was a once-in-a-universe event.

    And I should hope that they still think so, seeing as Mars does not have a huge Moon like ours... Despite evidence of an impact that COULD have created one, and yet didn't.

    1. Re:Hopefully. by MBGMorden · · Score: 5, Interesting

      IF you RTFA then you'll find no mention of some freaking 'Huge' moon being necessary to life. While it didn't appear in the article, I've seen quite a bit of stuff suggesting that a big moon could be a necessity. While the tidal issue is news to me, the most common thing I've heard quoted as that a large moon serves as an anchor for a planet, significantly reducing the amount of wobble in it's orbit. A wobble of less than 1 degrees can have serious climate impacts on Earth (the Sahara was once a jungle . . .), but we generally don't wobble much because of the moon anchoring us down. Other rocky planets like Mars or Venus wobble MUCH more, which would make climate conditions that would be difficult for life to spring up.

      IIRC, one special that I saw suggested that while life might have formed in the absence of the Moon, it probably would have been confined to the oceans only.

      --
      "People who think they know everything are very annoying to those of us who do."-Mark Twain
    2. Re:Hopefully. by Bombula · · Score: 4, Interesting
      A wobble of less than 1 degrees can have serious climate impacts on Earth (the Sahara was once a jungle . . .), but we generally don't wobble much because of the moon anchoring us down. Other rocky planets like Mars or Venus wobble MUCH more, which would make climate conditions that would be difficult for life to spring up.

      Depends on where in the timeline you're talking about. In the first 500 million years after the moon formed, it was so close to the Earth that the tides were 1 MILE high. Can you imagine a wall of water a mile high rolling tens or in some cases hundreds of kilometers inland several times a day? I think that probably had a signficant impact on the weather too, don't you? But who knows, maybe that was good for aiding the formation and establishment of simple life.

      --
      A-Bomb
    3. Re:Hopefully. by dreamchaser · · Score: 3, Interesting

      Extreme tides like that may well have helped spur the evolution of life. Proto-microbes washed onto shore and other materials washed back in. Think of it as a big huge mixing bowl.

      Some of those microbes may just have gotten stranded. Most probably died. A few probably adapted, living in shallow pools or clinging to rocks.

  2. lots of things can lead to fluctuations in pools by circletimessquare · · Score: 4, Interesting

    i understand why tidal pools can be thought of as interesting chemical incubators for life with all of the heating and cooling, wetting and drying that goes on, but a lot of other completely common and normal processes that can take place on a moonless planet can also lead to such incubators as well. waves, daily temperature variations, seasonal fluctuations, geography, etc.

    the moon does make us an interesting little quasi double planet system. but i think that that uniqueness does not go hand in hand with our planet's other unique trait, life. correlation is not causation looms large in my mind on this idea that the moon gave the earth life. no, the earth's chemical makeup, temperature, and atmospheric pressure putting us near water's triple point, with a lot of water around: that gave us life. every other detail seems secondary and not mandatory

    --
    intellectual property law is philosophically incoherent. it is your moral duty to ignore it or sabotage it
  3. Not exactly by sm62704 · · Score: 4, Interesting

    Mars Had an Ancient Impact Like Earth

    No it didn't. Like Earth, Mars had an ancient impact, but the impact itself was decidedly NOT like the impact Earth experienced.

    Earth's impact obliterated the Mars-sized object that impacted earth, leaving a ring of ejects circling the Earth. The ring coalesced into the moon. This didn't happen on Mars; Mars has no giant satellite, only two small moons.

    Also, I saw a few different accounts, and not everyone is yet convinced that the disparity between Mars' poles was caused by a giant impact. The San Fransisco Chrinicle, for instance, says "Huge impact may have divided Mars surface".

    In the past some scientists have held that the great divide on Mars was caused by the upwelling of semi-molten material from the planet's interior, or perhaps by several smaller meteorite impacts. But now the theory of a single giant impact has gained major support. It's an intriguing theory - most of it derived from computer calculations and NASA spacecraft. But one scientist expressed some modest reservations about it in a separate commentary in Nature.
    An interesting, yet probably non-answerable question occurred to me - If an object did smash into Mars, rather than hitting pole-on as the theory says (and I'm no astrophysicist and can't even spell it properly), which seems improbable to mee, seeing as how all the orbits of all the crap circling the sun seem to lie on a plane, could it have struck Mars' pole and then hit the next planet in (Earth), causing its moon?


    If this could have happened, could life have been on Mars at he time but completely wiped out, with its remnant chemicals starting life over on Earth?

    There have been meteorites that are Martians.

    --
    mcgrew's razor: Never attribute to stupidity that which can be explained by greedy self-interest
  4. Where's the ejecta? by thatseattleguy · · Score: 3, Interesting

    If this is true (a glancing blow by a huge object), I'm confused as to where the debris ejected from the collision would have ended up? Certainly not everything would have ended up melding with the main planet, especially (again) if this was a glancing blow. I'd expect some sizable amount of mass to be blown into orbit, as happened in the Earth-Moon formation event.

    Mars's two moons are incredibly tiny - IIRC more like smallish asteroids - so no coalescence of debris into a larger satellite as we have.

    Someone more awake in astrophysics class maybe can help with this.