UM-Flint Prof. of Physics & Astronomy on Asteroid 2005 YU55 Fly-By Between Earth & Moon


Uploaded by umflint1 on 08.11.2011

Transcript:
Dr. Ganguly: My name's Rajib Ganguly. I'm a professor of physics and astronomy at the
University of Michigan-Flint Department of Computer Science, Engineering and Physics.
So Asteroid 2005 YU55 is coming within say 9/10th of the moon's orbital diameter to Earth.
It's approximately the size of four football fields. Just to give you an idea of what the
scale of these things are I'm going to bring you over here. So here we have an Earth. I
have in my hand here a couple other objects. So if we take this as the earth, then the
size of this tennis ball which is about a quarter of the size of this earth, is about
the size of the moon. Now how far is the moon from the earth on this same scale? Well, I
have here a large classroom. This is about a 12 foot ball, or 12 inch globe here. We'd
have to go about 30 times the size of the earth to get at where the moon is going around
and that's about the size of this classroom here. So I put the moon over here and that's
about the right distance, that's about the right scale in terms of the size of the moon,
my tennis ball moon, and the distance between the moon and the earth. Now the earth is pretty
large compared to this asteroid. I'm gonna use this tack to represent the asteroid, but
there's a catch. I'm gonna use the head of the pin just so you can see it, but in reality
the size of the asteroid, to be more accurate, I would have to use the other size of the
pin, really tip of it. That's how big it is compared to the size of the earth. The earth
is about 6,000 kilometers across. This thing is about 400 meters across, several orders
of magnitude smaller. Now where is this asteroid, here I'll flip it over again just so we can
see it. Where is this asteroid going to be? Well it's about just under 9/10th of the moon's
orbit. So if the earth's way over there and the moon is way over here, about 9/10ths would
be say about here. So it's gonna be passing by just inside the moon's orbit like this.
It's actually even better for us actually because it's not even passing in the same
plane, it's passing above. So it's sort of up here. So that gives you sort of a sense
of the scale of 2005 YU55. Now things like this happen maybe once every 30 years. The
last time this happened for things this that were this size, was about 1976. Another one
will happen in 2028. Um, but of course, there's other schmutz around the solar system also.
Um, there was a, last Saturday there was another asteroid that passed inside the moon's orbit,
but that guy was only about the size of maybe my house. So these things happen all the time,
but things that are this big happen maybe once every 30 years or so.
Dr. Ganguly: Well depending on where it hit, if it hit, say land, we might get a crater
that's say 4 miles long and maybe a third of a mile deep. So something that's not even
close to the Grand Canyon. Grand Canyon is much larger.