I’d think that anything whacked off of Mercury would hit the Sun.
Do you guys have some math to back this up?
I am more interested in Terran meteorites showing up on Mars.
We should be getting some data from The World Ceres in late October.
Thanks, folks, I’ll be here all week.
Well, regardless of Chronos’ interpretation, theIAU definition of a planet includes the earth, but not the moon.
How do we know a lot of them rocks weren’t just leftovers from back when the moon was formed?
What about all these satellite moons we have floating around Earth?
There’s quite a few bodies of matter whipping around in close proximity of us. NEO’s.
I’m sure there are lot more rocks scattered about from earth, rather than the other way around.
(That is, if the moon formation was in fact, from a large Mars sized impactor that pummeled our home Planet into a molten rubble pile.)
How would a meteor strike on mars kick off ejecta all the way over here, unless the impact was pretty significant? I don’t see evidence of those type of large impact craters on Mars.
Also, there’s that Jupiter thing that has a far larger gravity well to pull stuff away towards the other direction, if a large impact did occur on Mars. :dubious:
A lot of it is about orbits and escape velocities - if something is ejected from Mars so as to escape its gravity, it could go anywhere - if it’s ejected in a direction opposite to Mars’ orbit around the sun, it will probably fall into a closer orbit, perhaps intersecting Earth - if it’s ejected in the opposite direction, it will climb to a higher solar orbit, maybe getting hoovered up by Jupiter - but even then, it could just pass close by one of the outer planets and be catapulted (or braked) back sunwards again.
Ejecting material from Earth takes a bigger event than from Mars, because Earth is bigger (more gravity to overcome) and has a thicker atmosphere (which may slow the ejecta to below escape velocity before it gets out)
I’m scratching my head trying to work out how you could interpret earth as not being a planet under the IAU definition. There seems debate about if Earth-Moon is a double planet system, but Chronos, how would Earth not be a planet?
You should go read it again. Their definition is:
is in orbit around the Sun,
has sufficient mass to assume hydrostatic equilibrium (a nearly round shape), and
has “cleared the neighbourhood” around its orbit.
The presence of the Moon is evidence that Earth has not cleared its orbit.
Well, it depends on what direction it’s whacked off. Most things whacked off of a planet won’t hit anything at all: Space is pretty empty, after all. Of the things that do eventually hit something, the most likely target is the original planet again, since after all, we know that the debris’ orbit must intersect the planet’s orbit. Beyond that, it could be almost anything. But note that the Sun is actually one of the harder targets to hit: It takes more change in velocity to kill the orbit and fall into the Sun than it does to reach escape speed, to hit objects further out.
Of the possible targets that are allowed by the energetics of the collision, the probability of hitting them is roughly proportional to the angular area of the targets as seen from the point of origin. It’s more complicated than this, of course, since orbits are dynamic and you can get all sorts of funky n-body interactions, but that’s about as good a first approximation as you’re going to get.
Well the post War of The Worlds ones say “Made in occupied Mars”.
A related question I keep forgetting to post: would any of the above-ground nuclear explosions theoretically been powerful enough to eject a rock from earth out into space? If so, would it have had enough energy to potentially travel to anothet planet? (And I’ll accept Chronos’s definition of a planet for purposes of this question!)
Here’s a definition of cleared its orbit. Satellites and resonant-orbit bodies don’t count against a body, because they still dominate them gravitationally.
Then I guess Mars Jupiter, Saturn, and Uranus are out, too.
Come on, think! That’s NOT what they mean by “clearing the orbit”.
You’re a smart guy, you can figure this out. Not that I necessarily agree with the IAU’s definition, or the process by which it arose.
Most probably would. But some could barely miss the sun and go into a highly eccentric orbit and go almost arbitrarily far out into the solar system, even without any extra “delta V” being imparted by the collision.
Maybe one of the Mercurian meteorites might approach Sol so closely that in its slingshot trajectory it could become superluminal!
<insert sheepish grin here>
Hey, I saw it on a documentary on TV once.
Say what?
So then Mercury and Venus are the only planets? Everyone else has moons.
“Cleared its orbit” refers to the situation where nothing is left in an orbit for a planetary body to smack into. Its like clearing a road through a mine field.
All obstacles have been cleared. For instance, our moon isnt ever going to collide with earth despite crossing its orbit.
Likewise, occasional rogue bodies, such as meteors and comets, do not need to be cleared, otherwise Mercury and Venus would also fail the definition of planet. Put it another way: nothing would be a planet.
That sounds like a really awesome way to scare the piss out of stupid people.
“The moon is going to cross the orbit of the Earth in the next week or so.”
What other planet-sized objects do Mars, Jupiter, or Saturn have orbiting the Sun in essentially the same orbit as themselves? And before you object that the Moon isn’t orbiting the Sun, the gravitational force of the Sun on the Moon is greater than that of the Earth on the Moon.
The gravitational force of the sun on the moon is greater than that of the earth on the moon.
Now may I say that the moon is orbiting the earth, not the sun?
I’m pretty sure the moon is orbiting the sun.