The Chelyabinsk meteor of 15th
February 2013:
We all know that a massive
asteroid the “2012 AH14 meteor” just passed some 27000 km from Earth on 16th
Feb 2013. Coincidently, a day before
this, another asteroid, a 10-ton meteor entered the Earth, lit up the sky over the Russian region,
exploded and hit the ground at Chelyabinsk on 15th Feb 2013.
This ‘Chelyabinsk meteor’
entered the atmosphere at a hypersonic speed of at least 54,000 kilometers per hour
and shattered into pieces about 30-50 kilometers above the ground level. NASA
estimates the meteor to be at least 55 feet across and possibly weighed about
10,000 tons. The impact made a crater on the outskirts of Chelyabinsk.
Video links:
What are Asteroids, Meteors and
Meteorites?
Asteroids are rocky objects
wandering in space. They vary in their size from a few meters to about hundreds
of kilometers wide. The bigger asteroids are also called as minor planets or dwarf
planets (if the asteroids are quite big) or planetoids. The famous asteroids
are seen as a belt of 750,000 rocky chunks lying between the orbits of Mars and
Jupiter. There are more than millions of asteroids orbiting the sun.
When an asteroid enters Earth’s
atmosphere (or any other planet), the asteroid begins to burn, light up due to
the frictional heat. Now it is called as a shooting star or meteor.
Many asteroids are completely
burnt up into ash before reaching the ground and some do reach the ground and
these are called as meteorites.
There are more than 165
terrestrial meteor impact craters on the Earth’s surface. The structure of such
Meteor Impact craters that appears like a scar on the
Earth’s surface is often referred to as an Astrobleme.
The following 10 are
the most amazing Impact Craters on Earth
1.
The
Kaali Craters (a group of 9 meteorite craters)
located in the village of Kaali on the Estonian island of Saaremaa (West
Estonian archipelago) in the Baltic Sea. The crater is about 4000 – 8000 years
old. The crater has a depth of 22 meters and a diameter of 110 meters.
2.
The
Tenoumer Crater is located in the western Sahara
Desert, Mauritania (North West Africa). It is 1.9 km in diameter and the edges
of the crater rise up to 110 meters high above the base of the crater. The crater
is estimated to be approximately 21000 years old.
3.
The
Lonar Crater can now be seen as a saline soda lake located
at Lonar in Buldana district of Maharashtra, India. The crater is about 1.2 km
in diameter with a depth of about 137 meters. The age of this crater is
estimated to be about 570,000 years.
4.
The
Monturaqui Crater is located south of the Salar de Atacama,
in the Antofagasta region of Chile (South Western part of South America). The
crater is about 370 meters in diameter and approximately 34 meters deep. The
crater is estimated to have been created some 660,000 years ago.
5.
The
Roter Kamm Crater is located in the Namib Desert in the
Karas Region of South West Africa. The crater is 2.5 km in diameter and 130
meters deep. The age is estimated to be between 4 and 5 million years.
6.
The
Tswaing crater also located in South Africa some 40
km north of Pretoria is formed into a salt lake. The crater lake is about 1.13
km in diameter and 100 meters deep and the age is estimated to be some 220,000 years. There is a Museum with a memorial to the
Astro-geologist Eugene Merle Shoemaker who showed that craters such as
Tswaing are formed by impact. He is better known for the discovery of the Comet
Shoemaker-Levy 9 which crashed into the Jupiter atmosphere between July 16 and
July 22, 1994.
7.
The
Pingualuit Crater is a perfectly round, water-filled
crater located in the Ungava Peninsula of Quebec, in the Canadian Arctic region.
This crater was formerly called as the Chubb Crater and later came to known as
the New Quebec Crater. The edge of the crater is elevated by about 160 meters
above the surrounding tundra and the crater is about 400 meter deep with a lake
depth of about 267 meters. The crater is estimated to be about 1.4 million
years old.
8.
The
Amguid Crater located in Algeria (North Africa), is approximately
530 meters in diameter and approximately 65 meters deep. The age of this crater
is estimated to be less than 100,000 years.
9.
The
Wolfe Creek Crater is the world’s second largest meteor impact
Crater located in the Western Australia. The crater measures about 875
meters in diameter and 60 meters deep from the rim to the crater floor with the
age is estimated to be less than 300,000 years.
10.
The Barringer Crater,
the world’s largest crater is located in the northern Arizona desert of the United States. It was formerly
known as the Canyon Diablo Crater. This carter is named in honor of Daniel
Barringer who first suggested that it was produced by the impact of a meteorite
that was later named as Canyon Diablo Meteorite. The edge of this crater is
elevated by about 45 meters above its surrounding plains. The crater is about
1,200 meters in diameter and about 170 meters deep and believed to be 50,000 years old.
-Dr. P. Kumarasamy
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