What Are the Chances That Earth Will Collide With Mars, Mercury, or Venus?

By Eliza Strickland | June 10, 2009 4:18 pm

Earth Mars collisionIs planetary Armageddon just a matter of time? Will Earth meet its fiery doom when the orbits of the planets in our solar system become destabilized, leading Mars, Mercury, or Venus to crash into our home turf? A new study predicts that there is indeed a very slim possibility that such a cataclysm will rock our world, but notes that the possible collisions wouldn’t happen for more than 3 billion years, by which time humans may be long gone. “I see the results as a case of the glass being 99 percent full and 1 percent empty…. While it’s possible that a collision could occur billions of years from now, it’s actually very unlikely” [SPACE.com], says Gregory Laughlin, an astronomer who wasn’t involved in the current research.

Astronomers had thought that the orbits of the planets were predictable. But 20 years ago, researchers showed that there were slight fluctuations in their paths. Now, the team has shown how in a small proportion of cases these fluctuations can grow until after several million years, the orbits of the inner planets begin to overlap [BBC News]. The researchers simulated the interactions of the eight major planets, Pluto, and the moon over the course of 5 billion years, up until our sun is expected to expand into a red giant. The simulation, described in the study published in Nature, covered more than 2,500 possible futures.

Study coauthor Jacques Laskar explains that for the first few million years, planetary orbits hardly differed from one run to the next. Eventually, though, variations began to accumulate. Most of the detrimental changes resulted from Jupiter’s gravitational tug on Mercury, the inner planet with the most lopsided orbit, Laskar says. In one simulation, Mercury collides with Venus about 1.76 billion years from now…. In three other simulations, Mercury’s orbit becomes so lopsided that it falls into the sun [Science News].

Most of Mercury’s maneuvers wouldn’t have much effect on Earth, the researchers say. But in one scenario, Mercury’s destabilized orbit pulls Mars into a lopsided orbit that brings it within 500 miles of the Earth in about 3.3 billion years, causing the Red Planet to break apart and shower Earth with debris. Using the idea of an Earth-Mars close encounter as a starting point, [the researchers] then ran another 201 simulations to assess the possibility that the near miss could lead to a direct collision. In 196 of those computer runs, one planet in the inner solar system either slammed into another or fell into the sun. Of those scenarios, Earth was struck 48 times: once by Mercury, 18 times by Venus and 29 times by Mars [Science News].

Related Content:
80beats: Spacecraft Will Search for Evidence of a Hypothetical Lost Planet
80beats: Planetary Pinball Accounts for Asteroid Belts and Gaps
80beats: Did an Asteroid Strike Billions of Years Ago Flip the Moon Around?
DISCOVER: Death by Cosmic Pinball tries to find the source of the dino-killing asteroid
DISCOVER: Geophysics: Is the Earth’s inner core simply the other half of our only satellite?
DISCOVER: Where Did the Moon Come From?

Image: J. Vidal-Madjar, IMCEE-CNRS

  • Patimus

    I’d venture to say, we probably shouldn’t worry about it. I’ll be 3,000,000,027, so a cataclysm will be a welcome change from the nursing home.

  • The Doctor

    Might have to take the Tardis to see this.

  • http://clubneko.net Nick

    Well, if we are here we damn sure won’t be human.

    Though, I predict that if our society lasts that long, the earth will be consumed by it far before we have to worry about hitting the other planets (which will probably be mined out well before ol’ earth is digested).

  • Jumblepudding

    If humanity has survived, it will be in a vastly different form, and will probably have moved away from the planet by the time something like this happens. I’d imagine our descendants at that point would be more different from us than we are from tunicates, possibly having shed consciousness as we know it as a vestigial encumberance. I think I just gave myself an aneurysm because my small imagination overheated.

  • YouRang

    The second episode of the current Dr. Who has the doctor showing Rose the end of the earth. The weird part was that surely someone would have implemented my plan by then. A fleet of about 1000 space stations orbiting between earth and Jupiter could transfer energy/angular momentum from Jupiter’s orbit to earth’s over a scant billion years. (Of course we’d need another set of about 200 to move Mars out of the way.)

  • Clark

    I think it’s safe to say it’s time to panic.

  • Brian

    I see a flaw. The orbits of Earth and all the planets mentioned have already been stable for 5 billion years. Why would they destabilize now? Are the researchers claiming new orbital mechanics suddenly arrive on the scene? Seems pretty unlikely.

    On the other hand, if it’s been the case that throughout the solar system’s history, the conditions causing “…these fluctuations can [to] grow until after several million years…” then I’d say that use case has been thoroughly tested out already.

    I’ll bet they either have a measurement error, a logic flaw, or they’re talking about a threat that’s so unlikely as to be insignificant. I’d be more concerned about a nearby supernova, gamma ray burst, or hostile aliens arriving. Heck, an asteroid impact is worth worrying over. We know the sun will die in 5 large ones.

    In short I’ll lose no sleep over this one.

  • DS

    Brian, I think the point is that there have always been these tiny fluctuations in orbits due to gravitational effects etc. Up until now however, they have been unnoticed because they are so tiny. But over time they will gradually accumulate as orbits become more and more irregular and eventually overlap.

  • chris

    Ooh I want to know if the earth is destroyed or if a saavy species plucks the artifact world from doom.

  • Gary

    I would love to see that from the safety of a ship lol.

    With cameras on the planets surface and sky to watch in super highdef.


    I wonder why do we exist in a universe and believe in man made gods?
    If your religious you need to address that seriously, I mean there has to be life out there.
    Soo did jesus die for their sins to? Are martians gonna burn or just be really compressed under mars surface?

    Another question.
    Is science from satan? Things like the theory of evolution or the theory or germs?
    Or the theory of gravity?

    Or computer science?

    I guess. Gotta limit that info.

  • Mitch

    #10 WTF?

    everything after amazing was kinda stupid.

  • sp

    #10 that statement was quite interesting

  • NATB100

    Well i think we should panic in the next few million years… or when you see the planet about to hit but until then i think we are safe (i hope, i am planning on passing away when i am about 139)

  • Matt


  • Messier Tidy Upper

    @ ^ Matt : Yeah, one day. So? 😉

    Fascinating glimpse into possibilities for the future there. Cool study & my (very belated, sorry) “good work and thanks” to its authors. :-)

    I presume they made allowances for our Sun being a red giant in about that time too?

    Personally, if Earth has to go – and it eventually does, nothing lasts for eternity – I’d rather our globe went with a bang than a whimper.

    Picturing a molten Earth and a molten Venus crashing together in mutual annhiliation just before the expanding surface of our dying crimson behemoth of a future Sun engulfs them both.


Discover's Newsletter

Sign up to get the latest science news delivered weekly right to your inbox!


80beats is DISCOVER's news aggregator, weaving together the choicest tidbits from the best articles covering the day's most compelling topics.

See More

Collapse bottom bar