A busy day for astronomers: Jim Teske's Blog

<B>(8:30 am Friday February 15th)</B> First a meteor explodes over Russia this morning and now this afternoon we await the near-earth pass-by from an asteroid. It is a busy time for astronomers.
The meteor in Russia is all the buzz Friday morning. The meteor entered the atmosphere becoming a fireball that then exploded over the southern Chelyabinsk region of Russia.  The sonic boom that was created blew out windows in many buildings and over 500 people were injured. Since it did not strike the earth, this is not considered a meteorite.

We are most familiar with meteors during several well defined periods during the year when clusters of meteors enter the earth’s atmosphere during what is called a ‘meteor shower’  You may have even sat out during the middle of the night in mid August to view the Perseid meteor shower and seen several ‘shooting stars’ a minute.  Even though we aren’t in one of these regular ‘meteor showers’ it is not unusual to have a meteor fall from the sky at any time during the year.

The fireball that you have seen on the video circulating the web is caused by friction as the meteor (made up of rock and metal) drops into the earth’s atmosphere. A meteor can be traveling at anywhere from 25,000 to 160,000 miles per hour when it slams into the earth’s atmosphere. The energy from this fast traveling meteor ‘excites’ the atmospheric atoms it comes in contact with creating the fireball tail. Here is a good primer on meteors from the American Meteor Society.

This meteor comes on the same day an asteroid, 2012 DA14, will come very close to earth.  The asteroid, which was discovered orbiting the earth last year by amateur astronomers,  will pass about 17.100 miles from the earth’s surface this afternoon.  That’s about 5,000 miles closer than the orbits of most of our weather satellite’s.

The folks at NASA have been tracking the asteroid and have calculated that it is not a danger to the planet. The asteroid is only about half the size of a football field and won’t be visible to the naked eye.  You can, however, check out the live feed from NASA’s Jet Propulsion Laboratory starting at 2 pm this afternoon. I believe they will have a telescope trained on the asteroid as it makes its pass of earth.

There are actually about 10,000 what are called ‘Near Earth Objects’  (either asteroids or comets) that orbit in this part of the solar system and about a tenth of those objects come within about four and a half million miles of earth

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