Asteroid to Make Closest Recorded Pass to Earth

unassimilatible writes "A 100-ft diameter asteroid will make the closest (26,500 miles, or about 3.4 Earth diameters) pass of earth ever detected in advance today, NASA reports. Asteroid 2004 FH's point of closest approach with the Earth will be over the South Atlantic Ocean. Using a good pair of binoculars, the object will be bright enough to be seen during this close approach from areas of Europe, Asia and most of the Southern Hemisphere. While we are in no danger this time, it is good to know NASA's LINEAR guys are on the job, for when that Death Star-sized object pays us a visit."

Comments

Huh?

[dolo666]

"100-ft diameter asteroid" ... "that Death Star-sized object"
The Death Star was bigger than 100 ft dia! Maybe the miniature Lucas used was that size? :-) If LINEAR can pick up 100ft dia objects, anything bigger would be easy. Now I can feel safe until this one veers off due our shoddy ozone, and smacks down on my hometown.

Re:Huh?

[Fishstick]

Really. Being hit by a planetkiller that causes extinction of humans on the earth doesn't worry me. Who will miss us?

My biggest fear is that we will be hit by a not-quite planetkiller that will cause enough devastation to ensure the survivors live in misery for the rest of their (short) lives. That would suck.

Lucky

[Space cowboy]

According to the article there are normally 2 of these every year. It seems a bit tongue-in-cheek to say "The important thing is not that it's happening, but that we detected it" [Chesley]. They were lucky, that's all.

It *will* give them a chance to study the thing as it passes, since all the other ones were only detected after they'd gone (and presumably therefore couldn't be easily studied). If it's close enough to see with binoculars, it ought to be possible to resolve quite well in a good optical 'scope.

The other point I guess is that it's only 100 ft across (why not 30m ?) so it would have burnt up on entry into the atmosphere, but still, good to know about these things. An asteroid that big would make quite some bang on entering the atmosphere, I reckon :-)

Simon

Re:Lucky

[lukewarmfusion]

I remember reading about NASA's (and others') ability to detect these in advance... apparently this science has improved immensely over the last ten years.

But you do bring up a good point - if this object would have hit Earth, would it have burnt up, or would something dangerous remain?

Much smaller items hit Earth all the time - they don't get burnt up completely. Of course, many end up the size of maybe pebbles or baseballs...

Re:Lucky

[Slowtreme]

Would this really burn up? Skylab was less than 50ft long and hollow inside. Many of it's parts made it to the ground. I'd image a solid rock hitting our atmosphere at that speed would not lose too much mass on the way in and do some pretty significat damage if it hit near a populated area.

This one is flying pretty darn close for comfort.

Re:Lucky

[sponge_absorbent]

it depends on the composition of the object and the angle and speed at which it enters the atmosphere.
I imagine that if it were a roughly spherical, dense, metallic object it would have a good chance of hitting the surface.

Re:Lucky

[mikerich]

you are an idiot, right? pressurce differences inside a solid mass?

No he's not.

It depends if it solid rock. many stony asteroids are apparently spongy having once contained volatiles that have subsequently been lost to space. These fragile objects will disintegrate in the atmosphere as atmospheric deceleration crushes them.

Its for this reason that carbonaceous chondrite meteorites - the black ones with the exciting organic compounds are relatively rarer on Earth than their abundance in space would suggest. We're regularly encountering them, they just don't make it through to the surface.

Having said that a 25m chunk of anything disintigrating in the atmosphere would produce a blast in the high kiloton, low megaton range. One of these smashing into a city would be a catastrophe.

And they seem to be more common than we think - there is obviously Tunguska in 1908, but then there are reports of something exploding over the Amazon basin in the 1930s, the more than 100 small impacts that hit Sikhote-Alin in Russia in 1947 and the most recently uncovered biggish impact at Wabar in Saudi Arabia - a Hiroshima-sized explosion in either 1863 or 1891 (there is no agreement on the date, since Arabic scholars saw two bright meteors heading in that direction on different dates, it's only recently that scientists have been able to determine the relative youth of the Wabar craters).

Best wishes,
Mike.

Re:Lucky

[Catbeller]

The rock would be moving at something like Mach 30 - at any rate at miles per second. The atmosphere is around 60 miles deep. It would be a blink. For it to be faster than a blink, for you, you'd have to know it was coming, be focused on the spot in the sky, and follow it. 60 miles/7 mps (supposing)= 9 and a fraction seconds to boom. Then you'd wait for the supersonic shock wave. Depends on how close you are to the impact(s). If you don't know it was coming, you'd maybe see a short flash of light, followed by death in a second or at most a minute or two. As for my Armageddon reference, I belive I was dead on. If you were in Manhattan, ground zero, you'd have seen a brief flash followed by a supersonic shock wave in less than a couple of heartbeats. It'd be like nuclear detonations, only without the radiation. As Heinlein said in The Moon is a Harsh Mistress, just like a sparks from a hammer. Just a really BIG hammer.

And shock waves aren't sound, so they can move quite quickly. The air itself would be moving at hypersonic speeds, mixed with vaporized solid matter from ground zero. Dust, really fast dust, and gravel.

And if...

[ForestGrump]

it was going to hit the earth and cause a massive extinction of the human race...
I highly doubt we will be told about it. Instead, our world leaders will gather in a cave somewhere with their mistresses and 500 years worth of refried beans...that ought to keep the human race going.

-Grump

Gravitational Effects?

[fishdan]

Any astronomers out there know if this will have a measurable gravitational affect on the planet? I know it's awfully small on a planetary scale -- but it's mass might be great. And, as I understand it, we're pretty good at detecting gravitational shifts. I know there won't be high tides or coastal flooding -- just if an object that small will have ANY noticable effect.

Hmm

[Czernobog]

Either there's an ever increasing number of asteroids coming ever closer to Earth (unlikely methinks) or this is truly indicative of how blind we have been all thse years to what was happpening in space.
Sort of puts our achievements into perspective...

I'd hate to be a

[Gr8Apes]

geo-synchronous satellite. 26km is just about their orbit. Shouldn't we try to protect them?!?

Re:How far away?

[TigerNut]

They didn't say anything about the relative angle at which the asteroid would be approaching. Geostationary sats occupy a fairly narrow belt around the equator (see, for example, this applet - assuming your computer is less Java-hostile than mine) 3D satellite simulator

Any object approaching from angles significantly above or below the equator will have only a very small chance of nailing a geostationary satellite.

We came pretty close.

[icejai]

It takes the earth about 6 minutes to travel a distance equivalent of its own diameter.
So basically, to avoid a direct hit, the the timing of of a near-earth-asteroid only needs to be altered by 6 minutes over the course of its orbit(s).

What I can't get over is that we *missed* this asteroid by only 12 to 18 minutes!

That's just crazy.