BREAKING NEWS --- Mars to be hit by massive comet! 40 billion nuke bomb size explosion! CONFIRMED!

Think of how difficult it is for humans to send objects to Mars. You can't just throw something out there and expect it to head straight to the nearest planet.

At their nearest point, Mars and Earth are 54.6 million kilometres apart. At their farthest point, 401 million kilometres. The two planets sit in two completely different orbits moving at different speeds. Anything headed toward Earth's orbit would be ultimately headed to the Sun, rather than a bee-line for Earth, and faces as much chance of meeting up with Earth as it crosses our orbit as any other asteroid or comet out there.

And, that's IF anything large gets flung out with enough velocity that it's actually able to escape Mars' gravitational pull (again, think about how difficult it is for humans to actually get stuff off our planet).

Sure, evidence tells us that pieces of Mars have made it here in the past, and some pieces from a Martian-Asteroid impact would probably make it here over time, but the odds are that it would take a VERY long time. Space is very big.

Um I think you are quite wrong on that. I think it would only take maybe 6 months tops for any Mars ejecta to reach Earth in the form of meteorites

Based on what? Do you believe, out of all the directions that debris could travel, that it will all somehow be making a beeline for Earth?

The reason why I think it would take a very long time is because it is very unlikely that anything ejected from the surface due to an impact will be headed straight for Earth. More likely, some pieces will eventually wander their way over to Earths orbit where we'll eventually run into them.

Last Edited by phoomp on 03/03/2013 12:35 AM

You're doing an awful lot of "imagining" in your "theories". How about a little math?

Also, since the asteroid will be travelling from the outer solar system, and since you believe that ejecta will be launched in the opposite direction of the asteroids direction, isn't it most likely that the ejecta will be headed back to the outer solar system, under your "theory"?

Good point. Maybe a possibility. Who knows. We shall find out soon. :)

Indeed.

The reason why it would likely take a very long time is because it is very unlikely that anything ejected from the surface due to an impact will be headed straight for Earth. More likely, some pieces will eventually wander their way over to Earths orbit where we'll eventually run into them.

Last Edited by phoomp on 03/03/2013 12:40 AM

well, the rules for our ejecta, as the Comet is striking
the surface of Mars are governed by Newtons Third Law of
Motion (action and equal and opposite reaction).

and, according to Newton's First Law of Motion: a body in motion will stay in that motion until or unless it is
acted upon by another body.
so, in terms of our "ejecta", yes, once the ejecta breaks
free of Mars gravity it will keep going in the same direction
with the very same constant velocity (until it is hit
by some asteroid or it travels close to the gravity of a mass planet)

That's not completely accurate. A significant portion of the asteroids motion-energy will be converted into heat-energy on impact. As a result, debris ejected from the Martian surface will not be travelling away with the same velocity that the asteroid arrived with (think about a Newton's cradle, which slows down because each ball impact results in a loss of inertia as motion-energy is converted into heat-energy).

fair enough. but at 120,000 miles per hour impact speed,
it think it's fair to presume that a whole lot of the
ejecta will reach Mars escape velocity.

Perhaps. It really depends a lot on the composition of Mars and the comet. This is not much different from throwing an object at the ground (albeit on a somewhat different scale). (i.e. debris behaviour will be different if the object is a rock, a sandstone or a snowball)

Yes, there will likely be debris ejected into space from the impact. What direction will the debris be headed will depend on the direction of the impact and gravitational forces. We know that:
- Siding Spring is coming from the outer solar system
- Siding Spring is currently BELOW the planetary plane
- Siding Spring orbit is in the opposite direction of the planets
- On Oct 14, 2014, Earth in it's orbit will be ahead of Mars, 1/4 of the way around the Sun from Mars and travelling away from the point of impact at a speed of 66,000 mph.

To my untrained eye, this suggests that debris from the impact will most likely be directed into the path of Mars' orbit or back out to the Outer Solar System. Some will likely decay it's way into Inner Solar System orbits, but that'll likely take a long time.

Here's my layman's sketch of my of what I've read about Siding Spring's path overlayed on top of the planetary positions for October 14, 2014:
[link to www.dropbox.com (secure)]

Last Edited by phoomp on 03/03/2013 11:33 AM

This sudden new cosmic situation is in a state of flux and is constantly changing. Thus it is perfectly understandable for a reader to use his/her own imagination as to what it is likely to happen in Oct 2014. There is also the possibility of new variables entering the astronomical equation between now and Oct 2014. Why, it is less than one year ago we first learned about these two comets and less than 2 months ago about the Martian-bound one!
As for the maths, even that is changing by the day when new info comes in.

Convenient.

very nice. thank you.
yes, it is clear that all of the ejecta will be directed
directly away from the Earth, and go way way out to the
outer planets.

which leaves the only remaining threat: when Mars is
broken into pieces, the gravitational influence of "Mars"
will be gone, and the Earth will be sucked into orbit around Venus.

Not confirmed yet. Hope it will be soon.


And lol at those who think it will destroy mars.

Very welcome.



Diameter of Siding Spring Comet: 10km - 50km
Diameter of Mars: 6,778km

Even with a potential impact strength of 2×10¹º megatonnes, it seems unlikely that Mars is so brittle that something 0.7% of it's size could shatter it. For a layman's scale model test, shoot a bullet at a boulder and see what happens.

Last Edited by phoomp on 03/03/2013 12:46 PM

ouch! you got me :)

OP. Please stop, you are only embarrassing yourself. You obviously have no knowledge of this subject.

;)

I've got another one for you. Even IF Mars were to disappear, the gravitational force it exerts on Earth is VERY minimal. Jupiter exerts more force on Earth than Mars does, and it's still just a fraction of what the Sun exerts on us. What keeps us a nice, cozy distance isn't the Outer planets holding us back; it's the speed and trajectory of our orbit around the Sun.

Astro, you know your stuff, with some much going on this year in space, what telescope would you recommed with a budget of around £250, $400? really would like my kids to get into this, like I did when I was younger but fell away, but I think with some amazing comets coming this year, there hasnt been a better time to get back into it?

Thanks

For $400 I would get one of these:
[link to www.telescope.com]
A good Dobsonian can provide many years of enjoyment. It's easy to use and a good tool to learn with, so great for the kids. Depending on their age it may be a bit big for them though, so if that's an issue you could always start off with something like this:
[link to www.telescope.com]

Last Edited by Astromut on 03/03/2013 08:33 PM

they are 5 and 7, I will have a look, thank you for the advice

Wow, this thread was dead on over a year ago. Should be getting a lot more attention. Talk about calling it.