If the Earth were hit by another Earth...

[Leovinus]

If there was an Earth-sized hidden rocky planet out in the Ort cloud so far away that we couldn't see it that one day came screaming in at us at the speed of Halley's comet and hit the Earth dead-on, what do you think the result would be? Another asteroid belt? One big planet? Two planets in radically different orbits? <div class="Discussion_UserSignature"> </div>

 

[silylene old]

My guess is that the Earth and the collider would both be pulverized into millions of fragments, all different sizes.<br /><br />Some of the fragments would move into wild orbits, and eventually be captured by the Venus, Mars and Jupiter.<br /><br />The majority of the fragments would spread out more or less in Earth's orbit as a temporary asteroid belt. The Moon would then sweep up about 75% of these fragments over the next millions of years, and grow to become about 1.5x mass of the Earth. The other 0.5 masses would end up in Venus, Mars, Jupiter and the Sun.<br /><br />Maybe a few of the asteroids would become new moons to circle the object formerly called the Moon (which of course is no longer a moon). <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center"><em><font color="#0000ff">- - - - - - - - - - - - - - - - - - - - - -</font></em> </div><div class="Discussion_UserSignature" align="center"><font color="#0000ff"><em>I really, really, really miss the "first unread post" function.</em></font> </div> </div>

 

[lunatio_gordin]

That sounds like an awesome concept for a scifi story.

 

[tony873004]

I just simulated the collision. An Earth-mass object with an eccentricity of 0.9997 drops from the Oort Cloud and slams into Earth.<br /><br />The simulation makes the assumption that the objects will merge and the new object will contain the combined momentum of the original 2 objects.<br /><br />This assumption is wrong. However, the debris field will probably be spread out over a solar orbit whose average is close to this orbit.<br /><br />And, there's an infinate amount of ways I could set up the starting conditions. Did it strike the Earth inbound or outbound from the Sun, etc.<br /><br />But this should give a rough approximation of what can be expected.<br /><br />And I'd have to say that Silylene's assessment of the situation is pretty good. The orbit of the debris field crosses Mars' orbit, doesn't make it far enough from the Sun for Jupiter to be a major player, and comes close to the orbit of Venus.<br /><br />But the odds of this happening are next to nill. For every Earth-mass object that drops from the Oort Cloud and slams into the Earth, thousands or millions of other Earth-mass objects should drop through the inner solar system without colliding with anything. But to date, all that's ever been observed dropping from the Oort Cloud are comets.<br /><br />pic:<br />http://orbitsimulator.com/orbiter/newEarth.GIF<br />

 

[igorsboss]

Each mad scientist needs to have outlined an experiment which, if actually carried out, would have dire consequenses. Leo, you've just posted mine. (Evil mad scientists actually attempt to carry them out...)<br /><br />I am particularly interested in the spread of life through such extreme impact events. Could there be viable life in some of the ejecta?<br /><br />Ejecta can manage interplaetary journeys, but whether or not it can do that while successfully transporting viable life is a matter for debate.<br /><br />In the case of such an extreme impact event, might it be the case that some of the impact ejecta could manage to escape the solar system to enter and seed other planets in other systems?<br /><br />Perhaps Earth is already a second-generation planet, daughter of "Eden", an obliterated garden planet.

 

[nexium]

I think you are correct. As much as 1% of ejecta could leave our solar system. I think there is little evidence that life can be transfered on ejecta. Neil

 

[nexium]

Galactic planets likely can come from beyond the Oort cloud at ten times the speed of Hallys comet. Such extreme speed could eject half of Earth's mass from our solar system. Probability is very low as we have detected zero large bodies entering our solar system. Probability of a glancing blow is much higher than a head on direct hit. There is a good chance that there are zero Earth size or larger bodies in the Oort cloud. Neil

 

[igorsboss]

<font color="yellow">Probability is very low as we have detected zero large bodies entering our solar system.</font><br /><br />Here are some candidates for extreme planetary collisions:<br />1) Earth's moon is believed to have been created when a mars-sized planet struck Earth.<br /><br />2) Uranus' tilt may have been caused by an impactor. I would have expected a more eccentric orbit, however.<br /><br />3) The asteroid belt may be the remnants of an exploded or impacted planet, although this is theory is currently out-of-favor.<br /><br />4) Did Saturn's Rings come from an extreme impact event? (Probably something more mundane, like a comet...)<br /><br />Stick around for the real fireworks to come: When Andromeda impacts the Milky Way. Could any descendent of a terrestrial life survive such violence?

 

[lunatio_gordin]

I don't see why not, if we actually become an interstellar species. If we're trapped on earth still, Yeah, we're screwed.