Two Asteroids Come Close to Earth Today

[Doug]

According to space watchers, two asteroids are whizzing by the Earth today, closer than the moon's distance!

Asteroid buzzes Earth; another one coming - CNN.com

The first one already went by about 5:51 this morning, and the next one is due at 5:12 pm today. They're only about 50 feet across, so even if they did hit, it wouldn't mean the end of civilization or anything, but it does show that there is a need for closer monitoring and contingency plans in the future, so we don't end up like the dinosaurs.

When I was a kid, I used to have a dream that the earth was hit by a giant asteroid and knocked into the sun. This was before all the movies, too....

[rk]

Very interesting. It reminded me of a rather large meteoroid or asteroid that skimmed the atmosphere from NW to SE for a few hundred miles over the upper midwest earlier this year (April 14, 2010). It was visible from 7 states and eventually disintegrated over SW Wisconsin about 10 miles above the ground. It was caught by a few webcams and you can see the composite videos at the following link (the opening sequence is from downtown Milwaukee, over 90 miles from the fireball):

YouTube - Fireball Lights Up The Midwest Skies USA

[Doug]

I remember that. Good thing our atmosphere has a zapper built in!

[miamidesigner]

How destructive could an asteroid be if a decent size one actually hit the earth?

[rk]

How destructive could an asteroid be if a decent size one actually hit the earth?

Of course it depends a lot on the size of the meteorite, and the angle of impact, but even a moderately sized one can have a devastating effect. Consider the following photo of the Barringer Crater in central Arizona. It is almost a mile wide and 600 feet deep. It is estimated it was created 50,000 years ago by the impact of a meteorite about 150 feet across. Objects of this size strike the earth approx once every 1000 years.



Even much smaller objects (about 30 feet across) carry the energy of a nuclear bomb. They enter the atmosphere about once per year, and luckliy most burn up because of the shallow trajectory. I expect the one over the midwest this spring (video above) was of this category.

Objects over 3 miles in diameter strike the earth about once every 10 million years. The last such major impact was about 65 million years ago, had the energy of several million nuclear bombs exploding simultaneously, and wiped out most life on earth.

These are all averages, and it is difficult to predict when the next one may strike. There is a known asteroid about 1 km across that may strike the earth on Mar 16, 2880. Tracking each asteroid is very difficult - there are at least 2 million asteroids in the solar system with sizes greater than 1 km.

More info here: http://en.wikipedia.org/wiki/Meteor_impact

[Doug]

I remember going there as a kid in the 70s! It is really impressive to look at. I guess the atmosphere can only zap so much!

[miamidesigner]

Even much smaller objects (about 30 feet across) carry the energy of a nuclear bomb... Objects over 3 miles in diameter strike the earth about once every 10 million years. The last such major impact was about 65 million years ago, had the energy of several million nuclear bombs exploding simultaneously, and wiped out most life on earth.

Wow, that's crazy.

I took a trip to New York 3 years ago and watched a "show" in one of the Museums of Science and History, I can't remember the name right now but, the point is that the show I watched was about collisions in space and how a long long time ago there was a collision whose effects describes what you wrote above. It was all very interesting because it went on to explain how things came to be on earth.

It raised the question that since meteor hits are timed events, all pre-calculated what if we didn't have the science and technology to stop them as we do now, what if we are preventing something that is meant to be... to be.

[fredgarvin]

Very interesting. It reminded me of a rather large meteoroid or asteroid that skimmed the atmosphere from NW to SE for a few hundred miles over the upper midwest earlier this year (April 14, 2010). It was visible from 7 states and eventually disintegrated over SW Wisconsin about 10 miles above the ground. It was caught by a few webcams and you can see the composite videos at the following link (the opening sequence is from downtown Milwaukee, over 90 miles from the fireball):

YouTube - Fireball Lights Up The Midwest Skies USA

I'm very surprised no-one commented on how wonderful 'downtown' Milwaukee looks!

[rk]

I'm very surprised no-one commented on how wonderful 'downtown' Milwaukee looks!

Because some things are self-evident and need no comment?




(credit: photo is from Tripadvisor where you can find more photos of Brew City:
http://www.tripadvisor.com/LocationP...Wisconsin.html )

[fredgarvin]

Because some things are self-evident and need no comment?




(credit: photo is from Tripadvisor where you can find more photos of Brew City:
Milwaukee Photos - Featured Images of Milwaukee, WI - TripAdvisor )

There you go! Thanks RK! LOL!

http://upload.wikimedia.org/wikipedi...ee_skyline.jpg