Asteroid passes just 8,700miles from Earth

[classicman]

Although no one noticed at the time, the Earth was almost hit by an asteroid last Friday.

The previously undiscovered asteroid came within 8,700miles of Earth but astronomers noticed it only 15 hours before it made its closest approach.

Its orbit brought it 30 times nearer than the Moon, which is 250,000 miles away.

Astronomers believe the object, called 2009 VA, would have almost completely burned up while entering Earth's atmosphere, causing a brilliant fireball in the sky but no major damage to the surface.

The asteroid was discovered by the Catalina Sky Survey on November 6, 2009. It was then identified by the Minor Planet Centre in Cambridge, Massachusetts as a near Earth object.

Part of the devastation in Tunguska, Siberia, in 1908 after a meteorite struck.
The impact created a blast so powerful it leveled 1,200 square miles of forest



Holy crap!

[xoxoxoBruce]

A miss is as good as a mile.

[glatt]

But before you head for the nuclear bunkers you will be relieved to learn the tumbling rock was only 23ft across. Similar sized objects ... impact on the planet about once every five years.

[Clodfobble]

My question is, what happens if something of that size hits the moon? No atmosphere to burn it up, much smaller mass to have to absorb the impact... though I guess the gigantic craters prove that it's not going to knock the thing off course or anything.

[Elspode]

Alien probe, making a low-altitude overflight. Back on Gzyx X-11, the cephalopods are waving their tentacles in delight as they see positive proof that the Earth has plenty of liquid water, and no apparent signs of intelligent life.

[Urbane Guerrilla]

Originally Posted by Clodfobble

My question is, what happens if something of that size hits the moon? No atmosphere to burn it up, much smaller mass to have to absorb the impact... though I guess the gigantic craters prove that it's not going to knock the thing off course or anything.

There is an eleventh-century or so record of three monks sighting a substantial meteoroidal impact on the Moon. They had no idea this was what they were seeing but they described a fountain of sparks shooting from the Moon's southern limb, and the appearance of the limb splitting, becoming forked.

And there's a very fresh-looking crater just about there, too, big enough that the fireworks would have been naked-eye visible. They think that might be the one. A bit of asking around on an astronomy board like Bad Astronomy/BAUD might yield some idea of the meteoroid's size.

[ZenGum]

I've heard of the same events. I've also read that the moon is still reverberating from various impacts.

[Urbane Guerrilla]

The moon does resonate from sufficient impact. It's because it's solid to the core and has been for about the last 3 billion years. Entropy, however, damps the resonating in due course. Earth, with a core that is partly liquid and the most of that iron, damps the ringing much quicker.