Meteor explodes above Russian city

  

Video from YouTube shows the explosion of the meteor from a number of cameras.

Edited from CBC News:

With a blinding flash and a booming shock wave, a meteor blazed across the western Siberian sky Friday near the Russian city of Chelyabinsk and exploded with the force of 20 atomic bombs, injuring more than 1,000 people as it blasted out windows and spread panic  (fear) in the city of 1 million.

"There was panic. People had no idea what was happening," said Sergey Hametov of Chelyabinsk, about 1,500 kilometers east of Moscow in the Ural Mountains.

Windows damaged by the meteor explosion

Meteoroids are small pieces of space debris — usually parts of comets or asteroids — that are on a collision course with the Earth. They become meteors when they enter the Earth's atmosphere. Most meteors burn up in the atmosphere, but if they survive the frictional heating and strike the surface of the Earth they are called meteorites. 

 
While NASA estimated the meteor was only about the size of a bus and weighed an estimated 7,000 tons, the fireball it produced was dramatic. Video shot by startled residents of the city of Chelyabinsk showed its streaming contrails as it arced toward the horizon just after sunrise, looking like something from a world-ending science-fiction movie.  It was the largest recorded meteor strike in more than a century.

The meteor above western Siberia entered the Earth's atmosphere about 9:20 a.m. local time at a hypersonic speed of at least 54,000 km/h and shattered into pieces about 30-50 kilometers high, the Russian Academy of Sciences said. NASA estimated its speed at about 65,000 km/h, said it exploded about 30 to 38 kilometers above the ground, released 300 to 500 kilotons of energy and left a trail 485 kilometres long.

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How much is 300 kilotons of explosive energy?

Atomic bombs (2) dropped on Japan in 1945 -  Equal to 15 kilotons of explosive force (15,000 tons).

The Chelyabinsk meteor explosion was equal to at least 20 atomic bombs. 

People walk along a road in Hiroshima 1945. All the buildings were destroyed by the atomic bomb.

For a 10 kiloton blast at the height where it would produce the most damage, severe damage to frame (wooden) houses would occur out to 1.6 km and moderate damage to 2.4 km. A 10 kiloton blast would produce a fireball of about 300 meters in diameter and would cause moderate flash burns (second degree) at a range of about 2.4 km. A second-degree burn includes blisters, a darker tone and a shiny, moist appearance.

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The shock wave broke an estimated 100,000 square metres of glass, according to city officials, who said 3,000 buildings in Chelyabinsk were damaged. At a factory, part of the roof collapsed.

The meteor's shockwave damaged around 3,000 buildings including this zinc factory, where about 600 square metres of the roof collapsed.

The Interior Ministry said about 1,100 people sought medical care after the shock wave and 48 were hospitalized. Most of the injuries were caused by flying glass, officials said. A Chelyabinsk resident, Alexander Yakovets, told CBC News he was woken in his eighth-floor apartment by a "really horrible sound" that he first thought might have been a terrorist attack or a military exercise. He said he saw a very bright light and heard multiple explosions.

 NASA said the Russian fireball was the largest reported since 1908, when a meteor hit Tunguska, Siberia, and flattened an estimated 80 million trees. Chelyabinsk is about 5,000 kilometers west of Tunguska. The Tunguska blast, attributed to a comet or asteroid fragment, is generally estimated to have been about 10 megatons. For the full story, click here

Chelyabinsk

Trees flattened by the Tunguska meteor blast in 1908

Click here for more about the even bigger Tunguska explosion and what different scientist think may have caused it: https://www.youtube.com/watch?v=sF8HKCuA3DQ

Women in Combat

Edited from Scholastic News:

More than 200,000 women currently serve in the U.S. military. They make up about 15 percent of all service members. Until recently, women were barred from officially serving in combat units. Combat units engage directly in battle during a war.

That all changed on January 24, when the Department of Defense ended the policy that excluded women from serving in direct-combat positions.

“Women have shown great courage and sacrifice on and off the battlefield . . . and proven their ability to serve in an expanding number of roles,” Defense Secretary Leon Panetta said.

About 237,000 positions that have been closed to women could now be open to them under the new policy. Women would need to meet the same standards as men to get those jobs. Some positions may remain exceptions to the rule if the military finds that women cannot meet the requirements for those jobs.

Until now, women have only been serving in combat unofficially.

SUPPORT FOR THE CHANGE
General Martin Dempsey, Chairman of the Joint Chiefs of Staff, said that opening combat units to women will strengthen the military. President Barack Obama agrees.

“This milestone reflects . . . the indispensible role of women in today’s military,” Obama says. “Every American can be proud that our military will grow even stronger with our mothers, wives, sisters, and daughters playing a greater role in protecting this country we love.”

Public opinion polls show that Americans generally agree with allowing women into combat units. Recent polls by CBS News and the Pew Research Center, for example, showed that two thirds (66 percent) of Americans support ending the ban.

EQUAL ROLES
Dempsey and Panetta said the new policy reflects the realities of female soldiers’ changing roles over the past decade. More than 280,000 women have been deployed to Iraq and Afghanistan, and more than 150 have died.

Many of those women have served in combat unofficially. They’ve patrolled dangerous areas as military police, served as machine gunners atop military vehicles, searched Iraqi and Afghan women for weapons, and more.

Female machine gunner on top of a vehicle

New jobs will be opened gradually to women throughout the next few years. The entire process is expected to be complete by January 1, 2016.

“Everyone, men and women alike . . . is committed to doing the job,” says Panetta. “They’re fighting and they’re dying together. And the time has come for our policies to recognize that reality.”

A World War Two poster: women could serve in the US Army but they could not go into battle

South Korea's First Satellite Blasts Off

Edited from SkyNews:

South Korea has launched a satellite into space from its own territory for the first time - just weeks after North Korea accomplished a similar feat.

Satellites can be used for communications or for tasks such as observing the weather

The rocket blasted off from a launch pad in the southwestern coastal village of Goheung. Officials told cheering spectators minutes later that the rocket delivered an observational satellite into orbit. It is unclear whether the satellite is operating as intended.

A crowd watches the launch from a Seoul railway station

The launch is the result of years of efforts by South Korea - Asia's fourth-largest economy - to advance its space programme and confirm that it is a technology leader.

North Korea's long-range rocket program has generated international fears that it is getting closer to developing nuclear missiles capable of striking enemies. It has threatened to explode its third nuclear device.


South Korea tried and failed to launch satellites in 2009 and 2010, and more recent launch attempts were aborted at the last minute. The satellite launched by Seoul is designed to analyse weather data, measure radiation in space, gauge distances on earth and test how effectively South Korean-made devices installed on the satellite operate in space. South Korean officials say it will help them develop more sophisticated satellites in the future.

The rocket left from Goheung Space Centre

The South Korean rocket launched on Wednesday was partially designed and built by Russian experts under a contract between the two governments.