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View Full Version : Episode 29: Asteroids Make Bad Neighbours



Fraser
2007-Mar-26, 02:21 PM
Download the transcript  

Read the full blog entry (http://www.astronomycast.com/solar-system/episode-29-asteroids-make-bad-neighbours/)

lpgeorge123
2007-Mar-26, 11:26 PM
Ironically you guys plugged Q and BA the day after Phil announced that he's putting Q and BA on hold (http://www.badastronomy.com/bablog/2007/03/25/q-and-ba-episode-75-suspended-animation/) for awhile.

I know I'll be crossing my fingers and wait for it to return.

Fraser
2007-Mar-27, 03:36 AM
Yeah, I think we overwhelmed him. :-(

ximinez
2007-Apr-02, 06:30 PM
Asteroids make great neighbors. The problems arise when they drop in to visit.

CauchySchwarz
2007-Apr-04, 06:53 PM
Thanks for a great podcast.

I have one question, is a 1 km asteroid really big enough to wipe out humanity?. The one that formed the Chicxulub crater is supposed to have been 10 km in diameter.
While looking around the internet I've found some different accounts as to what kind of damage a 1 km asteroid would cause, from wiping all life off the face of the planet to destruction of a continent and global cooling.

Pamela: From 50m you destroy a city, but when you get up to 1km, you destroy the planet.
Fraser: You don’t actually blow up the planet?

Pamela: No, no. The Earth will still be there, and there will probably still be critters roaming around on it, but at this point you create essentially the asteroid impact version of the nuclear winter......

danscope
2007-Apr-04, 09:51 PM
Too bad they didn't have more time. I wonder how they would approach the problem of tumbling asteroids. These things have this nasty habit of rolling in space. ;)
" Yes....I had to spend four hours to bury the cat.
"Four hours?"
"Yes....he wouldn't keep still;kept wriggling about...."
*********
Well, othing is easy.
Dan

was2004
2007-Apr-10, 07:07 PM
first one, shouldn't the material that the asteroid is made of have a big impact ? since the energy will be a function of mass and speed, the mass would be very different if the object is ice vs. stone vs. iron ... or would the difference in density be trivial at this point ? hence a 1km iron asteroid vs. a 1 km iceball will have very different energies

second, why would detonating a nuclear bomb not be effective, it seems to me four things:
(1) the detonation would give the main body of the remainder of the asteroid a nudge if it doesn't detonate right on the center (conservation of angular momentum)
(2) a big detonation should scatter at least some of the asteroid's mass across a broad enough volume so that it wouldn't hold together gravitationally (what's escape velocity for an asteroid ?)
(3) even if all of the mass reaches the earth, the fact that the pieces would have a much bigger surface area than the single object would mean that you'd have more of the asteroid vaporize in the air rather than actually hit the surface
(4) if you've got the impact scattered over a wider area, you'd have less of a possibility of getting some of the side effects, namely volcanic eruption (the single piece would have more penetrating power) or tsunami (if they landed in the same body of water then the waves should interfere with each other

what do you think ? what am i missing ?

danscope
2007-Apr-11, 01:37 AM
Hi, No one has ever successfully made a dent in an icebreg, never mind an asteroid. And it has never been demonstrated that a nuclear explosion in a vaccuum would do much in the way of breaking up an asteroid.
Nuclear bombs , when detonated on earth, were detonated several miles above
ground zero for best effect, and that effect was both heat, and radiation in other spectrums. The intense heat is delivered in a shock wave front , the medium being air. If it was underwater, the medium would be water.
In space................what? the mass of a small suitcase? You might just make a lot of heat. Vaporize the mass in the bomb....80% of the force is radiated in other directions....just what actually tries to deflect or break up
the offending asteroid? ( I welcome opinions ).
Nuclear tests have been done underground, in a situation where the explosion can be moitored , and hopefully (but not always) contained. They drill a hole. Can't do that in space, unlike hollywood.
You might just do better taking some old Shuttle ME tanks and filling them with
water and accelerating them into the asteroid. It might do more good...but.
Perhaps they will one day practice on an asteroid that is no where near collision, and try to nudge it further away, and SEE what difference they make.
Cause and effect and observation. Something to do with scientific method.
Best regards, Dan

2001Intrepid
2007-Apr-24, 07:25 PM
Hi, I don't have the greatest understanding of astronomy, so hopefully someone has a simplified answer for me. I thought this article really explained many aspects of asteroid studies quite well and understandably too. My questions concerns whether all >1km asteroids will be found if they are outside the plane of the ecliptic. From the article she says:
"Nowadays there are multiple telescopes set up around the planet that scan each part of the sky along the ecliptic five times in a given night. They're constantly going through processing, looking for things and discovering new things on a regular basis and calculating the orbits in rapid fire"
and:
"There's a bunch of different programs that go out and take picture after picture after picture of areas specifically along the ecliptic in the sky. This is the area in the sky that the sun travels through and where we see all the planets. More or less, the majority of the asteroids and comets confine themselves to the ecliptic. There are some exceptions, things get thrown around through gravitational interactions and to find asteroids and comets, they look for things that move in their pictures"
So what about the other areas of the sky not on the ecliptic-Are systems in place that cover those others areas too? Thanks...
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