[typoon]

http://news.yahoo.com/s/space/200606...pastearthjuly3

An asteroid possibly as large as a half-mile or more in diameter is rapidly approaching the Earth. There is no need for concern, for no collision is in the offing, but the space rock will make an exceptionally close approach to our planet early on Monday, July 3, passing just beyond the Moon's average distance from Earth.
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Astronomers will attempt to get a more accurate assessment of the asteroid's size by “pinging” it with radar.

And skywatchers with good telescopes and some experience just might be able to get a glimpse of this cosmic rock as it streaks rapidly past our planet in the wee hours Monday. The closest approach occurs late Sunday for U.S. West Coast skywatchers.

The asteroid, designated 2004 XP14, was discovered on Dec. 10, 2004 by the Lincoln Laboratory Near Earth Asteroid Research (LINEAR), a continuing camera survey to keep watch for asteroids that may pass uncomfortably close to Earth.

Although initially there were concerns that this asteroid might possibly impact Earth later this century and thus merit special monitoring, further analysis of its orbit has since ruled out any such collision, at least in the foreseeable future.

Size not known

Asteroid 2004 XP14 is a member of a class of asteroids known as Apollo, which have Earth-crossing orbits. The name comes from 1862 Apollo, the first asteroid of this group to be discovered. There are now 1,989 known Apollos.

The size of 2004 XP 14 is not precisely known. But based on its brightness, the diameter is believed to be somewhere in the range of 1,345 to 3,018-feet (410 to 920 meters). That's between a quarter mile and just over a half-mile wide.

Due to the proximity of its orbit to Earth [Map] and its estimated size, this object has been classified as a “Potentially Hazardous Asteroid” (PNA) by the Minor Planet Center in Cambridge, Massachusetts. There are currently 783 PNAs.

The latest calculations show that 2004 XP14 will pass closest to Earth at 04:25 UT on July 3 (12:25 a.m. EDT or 9:25 p.m. PDT on July 2). The asteroid's distance from Earth at that moment will be 268,624-miles (432,308 km), or just 1.1 times the Moon's average distance from Earth.

Spotting 2004 XP14 will be a challenge, best accomplished by seasoned observers with moderate-sized telescopes.

On April 13, 2029, observers in Asia and North Africa will have a chance to see another asteroid, but without needing a telescope. Asteroid 99942 Apophis, about 1,000 feet (300 meters) wide, is expected to be visible to the naked eye as it passes within 20,000 miles (32,000 km). Astronomers say an asteroid that large comes that close about once every 1,500 years.

Observing plans

As 2004 XP14 makes its closest approach to Earth, astronomers will attempt to gauge its size and shape by analysis of very high frequency radio waves reflected from its surface.

Such radar measurements of the exact distance and velocity of the asteroid will allow for precise information on its orbit. From this scientists can also discern details of the asteroid's mass, as well as a measurement of its density, which is a very important indicator of its overall composition and internal structure.

Astronomers plan to utilize
NASA's 70-meter (230-foot) diameter Goldstone radar, the largest and most sensitive antenna in its Deep Space Network. Located in California's Mojave Desert, the Goldstone antenna has been used to bounce radio signals off other Near-Earth asteroids many times before, and it is now being readied to “ping” 2004 XP14 on July 3, 4 and 5.

Augmenting the Goldstone observations will be radar observations scheduled at Evpatoria in the Ukraine, commencing several hours prior to the July 3 observations at Goldstone.

Editor's Note: A SPACE.com viewer's guide for 2004 XP14 will be presented in Joe Rao's weekly Night Sky column on Friday, June 30.

At least it's not supposed to be a threat. It's amazing that this is going to be coming so close.

[Kevin]

[Chuckit]

It's going to be as close as the Moon. That's pretty near.

[andreas_g4]

Paging Bruce…

[demograph68]

I'll welcome it with a big hug.

[Dakar]

Originally Posted by Chuckit

It's going to be as close as the Moon. That's pretty near.

I wonder if that means we could pull it into orbit.

[cjrivera]

Just to be safe, let's send Ben Affleck up on a one-way shuttle to head off this menace.

[Demonhood]

reminds me of this video: http://www.youtube.com/watch?v=yYgEwXWilUc

the original has a japanese voiceover, but this one seemed more....ominous.

[Railroader]

Ronald Quincy - "I know the presidents' chief advisor, we were at MIT together. And, at this point in time, you really don't want to take advice from a man who got a C minus in astrophysics. The presidents' advisors are wrong. I am right. "

[His Dudeness]

We need Bruce Willis!

[Briareus]

"guess what guys? it time to embrace the horror"

[Landos Mustache]

I really hope it doesn't hit the earth before the Apple Keynote in August.

[ghporter]

The video left a few things to be desired. First, it showed a collision with a HUGE body-about 70% or so of the Moon. There are not that many such bodies just wandering around you know. And it didn't take into account the shockwave taht would wrap around the planet and shatter the crust on the far side. Even when a small object impacts Earth, it has effects globally, so a big body would have enourmous consequences. The Acropolis would not be just sitting there waiting for the Mediteranean to dry up; it would have been shaken to dust by the siesmic waves from the collision. In fact, a large body traveling at high speeds, as in the video, would cause supersonic shock waves to positively devastate the entire crust. So while the video wasn't as realistic as it might be, the lack of large enough to worry about objects anywherre near Earth (as in inside the orbit of the Moon) makes the issue pretty well moot.

[Lateralus]

Originally Posted by Landos Mustache

I really hope it doesn't hit the earth before the Apple Keynote in August.

Yeah, it'd suck to die with any money in the bank...

[Ozmodiar]

I'm more worried about one of those huge gamma ray bursts from black holes that will destroy the entire solar system, and we won't know about it until it gets here since they move at the speed of light.

Did I say worried? I meant I don't give a f*ck.

[Spook E]

IF this is coming close to the moons orbit, how come our gravity doesn't trap it like the moon is, or better yet, pull the asteroid in towards us?

[ghporter]

Originally Posted by Spook E

IF this is coming close to the moons orbit, how come our gravity doesn't trap it like the moon is, or better yet, pull the asteroid in towards us?

It's moving too fast. If it's going more than 17.4 miles per second it's beyond "escape velocity" for Earth, so the planet cannot "catch it." Most theorists currently feel that the Moon is a fragment of Earthfrom a cosmic collision with something roughly the size of Mars. THAT is scary; the entire planet was remodeled-rather drastically!

[CaptainUnbannable]

We should shoot at it just for practice. Just don't put those nasa guys in charge of the miles to kilometer conversions.

[reader50]

Originally Posted by ghporter

It's moving too fast. If it's going more than 17.4 miles per second it's beyond "escape velocity" for Earth, so the planet cannot "catch it." ...

Escape velocity for the Earth is approx 7 miles per second, or 11.2 km/s.

Anything entering from outside the Earth's effective gravitational field is already above escape velocity. It cannot be captured into orbit unless it loses some velocity due to friction with the atmosphere, or with help from a 3rd body's gravitational field.

note: While manmade space probes routinely use atmospheric braking to go into orbit of other planets, they are on very precise courses that take them back out of the atmosphere afterwards, at which time they use rockets to stabilize their final orbits. When a space rock has a close encounter with our atmosphere, the usual result isn't a stable orbit. It's crash & burn time, or rather the other way around.

[ghporter]

Oops, that was something like a major brain fart! I wonder where I got 17 miles per second... The 7+ miles per second is a number I learned so long ago that I can't imagine how I'd screw it up.

[tipperwah]

I just wonder, how can calculations have been done, showing there will be no affect on either the moon's gravity/orbit or the Eath's gravity/orbit - when we don't even know what the mass/size of the Asteroid is?

Wouldn't even an educated guess depend on an important peice of data like that ?

[Chuckit]

We probably know it's below a certain level, but not how far below.

[JoshuaZ]

With any luck it will crash into Earth and finally put an end to this global warming issue.

[Spook E]

^ Amen to that!

Why don't we test some asteroid busting technology on it and see how it goes? Oh yeah, we have none, roll on 2036!

[rickey939]

Superman will save the world.........again.

[ghporter]

I'm still in the "Send Ben Affleck to destroy the asteroid" camp, myself. Hey, it's worth a shot. He could sit on top of the Shuttle's external fuel tank for the ride up there...

[kick52]

who knows, maybe the egg heads at nasa miscalculated and it actually will hit earth and bring judgement day.

[Gator Lager]

Originally Posted by kick52

who knows, maybe the egg heads at nasa miscalculated and it actually will hit earth and bring judgement day.

well their was that incident with a mars mission a few years back. lockheed used metic and nasa ment for them to use standard measuring (or the other way around). regardless they messed up and hit mars with the spacecraft instead of landing on it.

well it's still a good shot to hit a planet from several million miles away.
that's a 3 pointer.

[nredman]

Deep Impact was on tv last night - I think the government is trying to tell us something

[amsalpemkcus]

Would be cool to start trying out some of these ideas:

Solar mirror
This would reflect light from the sun on to the asteroid to boil parts away. The stream of gases would move the asteroid out of the way of the Earth.

Paint
Covering the asteroid with paint or materials that either absorb or reflect light, heating or cooling bits and changing and way it moves.

Collision course
Smash a rocket or spacecraft into the asteroid to try to blow material away from the rock and change the asteroid's orbit.

Rockets
Land a rocket on the asteroid and use it to propel the rock in a different direction. Chemicals on the asteroid could be used.

From: http://www.guardian.co.uk/space/arti...579749,00.html