Unknown 7m Asteroid Almost Impacted Earth

xp65 writes "A previously undiscovered asteroid came within 14,000 km of Earth — just over one Earth diameter, 1/30 the lunar distance — on Friday, and astronomers noticed it only 15 hours before closest approach. On Nov. 6 at around 16:30 EST, a 7-meter asteroid, now called 2009 VA, came only about 2 Earth radii from impacting our planet. This is the third-closest known non-impacting Earth approach on record for a cataloged asteroid. The asteroid was discovered by the Catalina Sky Survey and was quickly identified by the Minor Planet Center in Cambridge MA as an object that would soon pass very close to the Earth. JPL's Near-Earth Object Program Office also computed an orbit solution for this object, and determined that it was not headed for an impact." The article notes, "On average, objects the size of 2009 VA pass this close about twice per year and impact Earth about once every 5 years."

Comments

Hardly noticeable if it impacted

[Conchobair]

Seven meters just isn't all that big. According to the Earth Impact Effects Program using typical data: No crater is formed, although large fragments may strike the surface. The air blast at this location would not be noticed.

Re:How Much Damage?

[dvice_null]

It would most likely bursts into a cloud of fragments at an altitude of 8980 meters. Minor local damage might occur if a larger fragment happens to hit a house.

http://www.lpl.arizona.edu/impacteffects/cgi-bin/crater.cgi?dist=0.001&diam=7&pdens=&pdens_select=8000&vel=17&theta=45&tdens=2500&tdens_select=0

Re:How Much Damage?

[olsmeister]

You can use this site to get an estimate.

Re:How Much Damage?

[Joey Vegetables]

And I forgot to consider that this was an object of 10 meters or so when it impacted Earth and was thus likely far bigger before entering the atmosphere. An object that was 10 meters before entering the atmosphere would, depending on composition and angle of descent, likely burn away completely before reaching ground. But there might be a midair explosion or fireball sufficient to ignite highly flammable structures.

Re:"Impact" Earth?

[mea37]

Hmmm... well, I realize that checking a dictionary first would've been a lot of work, but here's what m-w has to say about it. Note that the first entry is for the verb "impact".

Re:How Much Damage?

[SQLGuru]

According to this (I didn't verify any facts) - http://wiki.answers.com/Q/How_much_of_the_Earths_surface_is_inhabited_by_humans

About 1% of the surface is inhabited. So, an impact should directly affect people about once every 500 years. Maybe it's the next time?

Re:How Much Damage? Not much!

[zerosomething]

None. We were hit by one about 10 meters across on October 8th but no one wants to put the story out for some reason. http://neo.jpl.nasa.gov/news/news165.html

Re:How Much Damage?

[jd]

Asteroid Impact Calculator. Handy thing to have bookmarked, in the event that the astronomers see the next one from far enough off.

It's impossible to be sure what the density and angle of incidence would have been in this case, as this sort of data isn't usually published. It's also impossible to be sure of composition, as that depends on where the asteroid was from. Thus, any results you DO get from the calculator are either meaningless (too much garbage in) or extreme values only.

Having said that, such calculators are fun when they find truly massive craters. The crater under the antarctic ice, for example, is so large that the Earth was unlikely to have ever been hit by something that big in the past 4 billion years. Antarctica is very modern, in comparison.