久久久无码人妻精品无码_6080YYY午夜理论片中无码_性无码专区_无码人妻品一区二区三区精99

USEUROPEAFRICAASIA 中文雙語Fran?ais
China
Home / China / Life

After asteroid, a sigh of relief on Earth

By Henry Fountain | The New York Times | Updated: 2013-04-07 07:44

 After asteroid, a sigh of relief on Earth

Since an asteroid exploded over Chelyabinsk, Russia, in February, scientists around the world have been analyzing data from the event, hoping to better understand it. Jorge Zuluaga and Ignacio Ferrin via arxiu (top row sides); NASA (top Center); Images from stefan geens and ogle earth via Google earth and Youtube (bottom row)

 

Using an eclectic mix of crowd-sourced video, information from Google Earth and data from nuclear test-ban sensors, scientists have gotten a much more accurate picture of the small asteroid that exploded near the Russian city of Chelyabinsk in February.

But what is most clear is that while Chelyabinsk did not exactly dodge a bullet, the city was fortunate to be only grazed by it. "The people of Chelyabinsk were very lucky," Dr. Edward Lu, a former astronaut who now leads the B612 Foundation, a private initiative to detect similar asteroids, said in Washington in March.

The Russian meteor - which was about 18 meters in diameter and came in undetected at roughly 67,000 kilometers an hour - was almost 24 kilometers high when it blew apart. There were no deaths, and most of the 1,500 injuries were from glass as windows shattered when a shock wave hit the city 88 seconds later.

"If it had detonated closer to the ground, it would have been worse," said Dr. Margaret Campbell-Brown, a member of a team of researchers at the University of Western Ontario.

The Canadian team has calculated that the energy released in the Chelyabinsk explosion was the equivalent of about 440 kilotons of TNT, or about 30 times the power of the Hiroshima nuclear bomb.

That calculation was made with the help of data from a network of acoustic sensors set up to monitor compliance with the treaty to ban nuclear weapons testing. There are about 45 of the sensors worldwide.

Thomas Mutzelburg, a spokesman for the Preparatory Commission for the Comprehensive Nuclear-Test-Ban Treaty Organization, which is based in Vienna, said the explosion was detected by more than 20 of the sensors, including one in Antarctica nearly 16,000 kilometers from Chelyabinsk.

With knowledge of the energy and information about how fast the meteor was traveling, researchers were able to calculate the mass of the meteor, about 11,000 metric tons. "It's all about the kinetic energy of that body," which is related to its mass and velocity, said Richard P. Binzel, a planetary scientist at the Massachusetts Institute of Technology. "All that kinetic energy has to be released."

The Canadian researchers have used video images of the meteor's east-to-west trail above Chelyabinsk to help calculate its trajectory and orbit. Since the explosion occurred in daylight, Dr. Campbell-Brown said they asked a colleague there to take night photographs from the same locations. By superimposing the images of the meteor's path over the night images containing stars, the researchers should be able to plot the path even more accurately.

For now, though, they and other teams, including one from the University of Antioquia in Medellin, Colombia, have established that the meteor originated in the inner part of the asteroid belt, in a regular, harmless orbit around the Sun between Mars and Jupiter. It then circled the Sun every 18 months in a highly eccentric orbit - more than two and a half times the Earth-Sun distance at its farthest - before it smacked into Earth.

Dr. Jorge Zuluaga, a member of the Colombian group, said he was inspired by work done soon after the event by Stefan Geens, a blogger in Stockholm. Mr. Geens used several videos to triangulate the path. The video does not show the explosion directly, but rather the shadows of lampposts, which moved like the shadow on a sundial as the fireball crossed the sky.

Dr. Zuluaga thinks that eventually it will be possible to reconstruct the rock's orbit so precisely that researchers may be able to detect it retroactively, by poring over images from sky-surveying telescopes taken the last time it flew near the Earth. "Then we can assign it a name," he said.

The videos that were posted online contributed to a surge in interest in projects to detect asteroids. Dr. Lu said his foundation had seen an increase in donations since the explosion.

"It made it more real to folks," he said. "There's nothing like a hundred YouTube videos to do that."

The New York Times

 

Editor's picks
Copyright 1995 - . All rights reserved. The content (including but not limited to text, photo, multimedia information, etc) published in this site belongs to China Daily Information Co (CDIC). Without written authorization from CDIC, such content shall not be republished or used in any form. Note: Browsers with 1024*768 or higher resolution are suggested for this site.
License for publishing multimedia online 0108263

Registration Number: 130349
FOLLOW US
久久久无码人妻精品无码_6080YYY午夜理论片中无码_性无码专区_无码人妻品一区二区三区精99

    欧美国产日本视频| 亚洲婷婷国产精品电影人久久| 国产片一区二区三区| 国产成人精品免费视频网站| 中文字幕第一区二区| 99re6这里只有精品视频在线观看| 一区二区三区在线免费观看| 欧美精品在线视频| 国内不卡的二区三区中文字幕| 中文字幕不卡在线播放| 91福利在线观看| 蜜桃久久久久久| 国产精品久久久久久久久免费桃花| 一本色道久久加勒比精品| 天天av天天翘天天综合网色鬼国产| 欧美一区午夜视频在线观看| 国产高清精品网站| 亚洲一区二区欧美激情| 日韩欧美激情四射| av成人老司机| 五月综合激情婷婷六月色窝| 国产午夜精品在线观看| 在线观看国产91| 国产一区欧美一区| 一区二区三区久久久| 精品久久久影院| 91免费看片在线观看| 免费观看久久久4p| 中文字幕一区二区三区精华液 | 亚洲美女屁股眼交3| 欧美一级xxx| 国产成人精品亚洲777人妖| 亚洲资源在线观看| 欧美精品一区二区精品网| 色偷偷成人一区二区三区91 | 不卡在线观看av| 丝袜美腿高跟呻吟高潮一区| 欧美激情一区二区三区不卡| 欧美日韩一区二区三区在线看| 国产精品1区二区.| 亚洲成精国产精品女| 中文字幕乱码亚洲精品一区| 欧美精品丝袜中出| 91尤物视频在线观看| 黄页视频在线91| 亚洲国产美国国产综合一区二区| 国产欧美日韩久久| 91精品久久久久久久99蜜桃| 99国产精品一区| 欧美视频一区二区三区四区 | www.亚洲色图| 六月丁香婷婷色狠狠久久| 一区二区三区色| 国产人成一区二区三区影院| 欧美丰满美乳xxx高潮www| 99re这里只有精品6| 精品在线一区二区三区| 亚洲成精国产精品女| 国产精品初高中害羞小美女文| 欧美哺乳videos| 欧美人与z0zoxxxx视频| 91热门视频在线观看| 国产成人一级电影| 久久国产精品99久久久久久老狼 | 韩国精品主播一区二区在线观看 | 日韩精品一区二区三区中文精品 | 久久九九全国免费| 日韩一区二区在线播放| 欧美影视一区二区三区| 成人av网站在线观看| 国内精品久久久久影院色| 日韩成人av影视| 亚洲综合网站在线观看| 亚洲欧洲日韩在线| 国产免费久久精品| 精品成人一区二区三区| 日韩视频免费直播| 欧美精品1区2区3区| 欧美性极品少妇| 一本久久精品一区二区| 成人91在线观看| 高清beeg欧美| 国产传媒久久文化传媒| 国产制服丝袜一区| 久久99精品国产麻豆婷婷| 免费一级片91| 日本色综合中文字幕| 日日骚欧美日韩| 亚洲高清视频的网址| 亚洲午夜国产一区99re久久| 亚洲综合在线观看视频| 亚洲精品欧美激情| 亚洲欧美激情小说另类| 亚洲精选在线视频| 亚洲免费在线电影| 一区二区三区精密机械公司| 一区二区三区精品| 亚洲一级二级在线| 亚洲成人av在线电影| 亚洲成人高清在线| 日本欧美加勒比视频| 青青草91视频| 久久精品国产亚洲5555| 韩国视频一区二区| 国产精品亚洲一区二区三区妖精| 国产一区二区三区av电影| 国产精品一二三四| 成人免费高清视频| 91亚洲永久精品| 91国产免费看| 欧美日韩高清一区二区三区| 制服.丝袜.亚洲.中文.综合| 欧美一区二区三区视频在线 | 欧美美女网站色| 欧美一区二区三区免费| 欧美不卡在线视频| 国产婷婷精品av在线| 国产精品麻豆99久久久久久| 成人免费小视频| 亚洲一区精品在线| 午夜久久久久久| 蜜桃视频第一区免费观看| 国产主播一区二区三区| 国产成人av电影在线| 成人国产电影网| 色屁屁一区二区| 欧美精品乱码久久久久久按摩| 欧美一级欧美一级在线播放| 精品88久久久久88久久久| 久久午夜色播影院免费高清| 亚洲欧洲性图库| 亚洲大片在线观看| 精品一区二区三区视频在线观看| 国产91精品久久久久久久网曝门| 91在线观看视频| 欧美老女人在线| 久久久91精品国产一区二区精品| 国产精品久99| 性做久久久久久| 国产一区不卡视频| 91亚洲精品久久久蜜桃| 欧美精品亚洲二区| 国产日产欧美精品一区二区三区| 亚洲精品欧美激情| 精品一区二区三区在线播放视频| 成人国产视频在线观看| 精品视频全国免费看| 久久综合久久综合九色| 亚洲人成亚洲人成在线观看图片| 天天免费综合色| 国产suv精品一区二区三区| 欧美亚洲国产bt| 精品999在线播放| 一二三四社区欧美黄| 久久99最新地址| 一本到高清视频免费精品| 日韩一级视频免费观看在线| 国产精品久久久久久久久免费相片 | 日韩一级视频免费观看在线| 国产精品看片你懂得| 日韩二区三区四区| 不卡一区在线观看| 日韩欧美黄色影院| 亚洲乱码国产乱码精品精小说| 久久精品99国产国产精| 色综合色综合色综合色综合色综合 | 日本中文字幕一区二区有限公司| 国产 日韩 欧美大片| 欧美日韩国产综合久久| 国产精品丝袜黑色高跟| 奇米影视在线99精品| 99re视频这里只有精品| 精品人在线二区三区| 一区二区三区精品| 国产传媒欧美日韩成人| 制服丝袜亚洲网站| 樱花草国产18久久久久| 国产毛片精品视频| 4438x亚洲最大成人网| 亚洲免费观看高清完整版在线 | 日韩欧美一卡二卡| 一区二区三区丝袜| 成人免费视频播放| 日韩精品一区在线观看| 亚洲va天堂va国产va久| av亚洲精华国产精华精华 | 亚洲最新在线观看| 成人激情免费网站| 2020日本不卡一区二区视频| 亚洲成人动漫av| 91蝌蚪国产九色| 中文字幕成人网| 国产精品91xxx| 欧美xxxxxxxxx| 日韩国产精品久久久| 在线免费不卡电影| 中文字幕一区二区三区四区不卡 | 亚洲福利一二三区| 一本大道久久a久久精二百| 国产精品无码永久免费888|