New Crater On Moon Caught On Video

From A Far Away Land writes "NASA has released a video clip of a meteorite striking the surface of the Moon. From the article: 'On May 2, 2006, a meteoroid hit the Moon's Sea of Clouds (Mare Nubium) with 17 billion joules of kinetic energy -- that's about the same as 4 tons of TNT," says Bill Cooke, the head of NASA's Meteoroid Environment Office in Huntsville, AL.'"

Comments

Re:Do it like they do on the Discovery channel...

[NewbieProgrammerMan]

Imagine if what hit the moon hit a major city...

I understand your point - anything large enough to make it through the atmosphere into a city could be mistaken for an attack by terrorists or perhaps another country. However, for a rock of this size TFA actually says:

If a rock like that hit Earth, it would never reach the ground. "Earth's atmosphere protects us," Cooke explains. "A 10-inch meteoroid would disintegrate in mid-air, making a spectacular fireball in the sky but no crater." The Moon is different. Having no atmosphere, it is totally exposed to meteoroids. Even small ones can cause spectacular explosions, spraying debris far and wide.

Re:Sagan's account

[canatech]

Try this -

http://en.wikipedia.org/wiki/Giordano_Bruno_(crate r)

Re:Obligatory

[kalpaha]

I'm sorry, but you're wrong! Everyone knows mars bars (278 kilocalories) is the real unit of explosion strength.
Google does these kind of calculations very easily: enter
17 billion joules / 278 kilocalories

into google, and you will receive the answer:
(17 billion joules) / (278 kilocalories) = 14 615.4587

So the explosion was ~14615 mars bars.

Re:Do it like they do on the Discovery channel...

[NereusRen]

Imagine if what hit the moon hit a major city...

That small of an object (only 10 inches diameter?) would burn up in our atmosphere. It only struck so hard on the moon because there's nothing slowing it down before it hits the surface. I went over to the trusty Asteroid Impact Simulator for a quick comparison. The smallest size you can select is 1 meter in diameter, but here's what it has to say about a fairly average 1m projectile "hitting" earth:

        Energy before atmospheric entry: 2.27 x 10^11 Joules = 0.54 x 10-4 MegaTons TNT [note: the one that hit the moon only had 1.7 x 10^10 Joules of energy... less than one tenth of this hypothetical.]
        The average interval between impacts of this size somewhere on Earth is less than 1 month.
        The projectile bursts into a cloud of fragments at an altitude of 49200 meters
        No crater is formed, although large fragments may strike the surface.

We only need to be worried about meteors a few orders of magnitude larger.

(Hell, TFA even explained that it would burn up, but I guess I can't expect anyone around here to know that...)

Re:Thanks for leting us know Nasa , 4 weeks after.

[SETIGuy]

Is this how we will be warned if one is heading to hit the earth ? After the fact ? I don't understand we put so much money into that agency and yet they keep messing up. Come you rocket scentist get your game on.

Ummm, 4 tons TNT equivalent? Who cares. One of these hits us daily and we don't seem to notice.

20 kiloton airbursts (5000 times bigger, think Hiroshima) happen annually and we don't notice those.

The 20 megaton airbursts (5 million times bigger, think Tunguska) that happen every hundred years or so, those we notice, some of the time, maybe.

It's somewhere around 20 gigatons (5 billion times bigger) that we need to start worrying that more than a couple people might get hurt.

Re:So what are the odds

[Wheatin]

While the atmosphere does break up some potential meteorites there are still quite a few impacts. The reason we don't see much evidence of this is that many hit the oceans, and the ones that do hit land are (relatively) quickly masked by natural erosion and vegetation. Plate tectonics can also break them up over time, and lava fills many of them in. The atmosphere plays a big part in these, I know, but the point is that the number of impacts between the moon and the Earth is not that different. It's just that the moon has been collecting them for billions of years and they're never worn away or covered.

Re:Sagan's account

[Anonymous Coward]

No, it is not really found in Psalm 95, nor in any psalm as far as i know. It is a doxology, which means that it is a sort of mini-prayer which is typically appended to another prayer.

The reason you found it in that particular webpage is that the webpage is derived from a tradition based on the Liturgy of the Hours. The Liturgy of the Hours is mostly structured around psalms and for each psalm basically follows the pattern: antiphon - psalm - doxology - psalm-prayer - antiphon. This form is sometimes stripped down for simplicity, but in this particular case the doxology was retained. Psalm 95 is particularly well-known as an invitatory to prayer, and so it is sometimes called by its first word in Latin, "Venite".

Regarding Carl Sagan, he was a smart guy, but sometimes he would repeat what amounts to the scientific version of an urban legend. One example is the "Heike" crabs, which look sort of like they have scowling human faces on their backs. In "Cosmos", Sagan explained that this was due to the local fishermen tending to throw back the more human-looking crabs. This is a plausible explanation, but it is actually wrong. The characteristic appearance of that family of crabs predates homo sapiens.

Re:New Crater in Iraq

[Anonymous Coward]

The USAF dropped two 500lb bombs on Zarqawi's house. Even if you were to make the extremely conservative assumption that 1000lb of today's munitions is equivalent to 1000lbs of TNT...

From last Friday's "Explainer" (Daniel Engber):

Does a 500-pound bomb really weigh 500 pounds?

No. Zarqawi got hit with two different weapons--a laser-guided bomb called the GBU-12 and a satellite-guided bomb called the GBU-38. They weigh 606 pounds and 552 pounds, respectively.

Both weapons are considered "500-pound" munitions because they're based on a standard 500-pound bomb known as the Mk 82. The body of an Mk 82 is augmented with a fuze, a guidance system, and other accessories like wings and tail fins; all of these add to its total weight.

But the Mk 82 itself packs only about 200 pounds of explosives. It gets the rest of its weight from a steel case, about half an inch thick, that helps to penetrate targets and provides material for fragmentation.

The "500-pound" designation doesn't give you much information about how powerful a given weapon might be. It's more useful for figuring out how many bombs will fit onto your aircraft.

-mcgrew (MRC?="economy")

Re:Colony on the moon

[shotfeel]

And add to that they've just started watching for these, so impacts of this size are not all that uncommon. And I'm with you in assuming there are probably many more, smaller impacts that occur. Just a couple quotes to indicate frequency:

During a telescope test last November 7th, Suggs and Swift recorded an explosion on their very first night of observing. A piece of debris from Comet Encke struck the plains of Mare Imbrium, making a crater about 3 meters wide."

Now that regular monitoring has begun, Cooke's group has already found a second impact, the May 2nd event, in only 20 hours of watching.

And that's for the small portion of the surface they're actually monitoring.