發信人: lauw.bbs@ptt.cc (新港解說營) 看板: astronomy
標  題: [新聞] 報應女神」讓恐龍滅絕！NASA努力尋找兇手！
發信站: 批踢踢實業 (2010/03/16 Tue 00:02:48)

報應女神」讓恐龍滅絕！NASA努力尋找兇手！

http://www.nownews.com/2010/03/15/91-2580015.htm
國際中心／綜合報導

是誰讓恐龍滅種？美國太空總署(NASA)的科學家指出，一顆被喻為「死亡之星」(Death


Star)、圍繞太陽運行的矮星「報應女神」可能是兇手。六千五百萬年前地球上恐龍滅絕

(呃…看到這個就不自覺地笑了起來…死星是星際大戰裡的太空要塞)


的主因，科學家相信跟地球不時受彗星撞擊威脅有關，NASA從今年一月開始，就開始利用


太空望遠鏡掃描太空，希望找出這顆神秘星體。

科學家指出，這顆被稱為「報應女神」(Nemesis)的矮星，距離地球約三分之一光年，亦

即地球和太陽之間距離的二萬五千倍，體積約為木星的五倍，但實際位置不明。科學家相

信太陽系被一層巨大的冰體雲團奧爾特雲（Oort Cloud）包圍，而「報應女神」的引力會

(國內譯為歐特雲…奧爾特雲對岸的譯法)


令奧爾特雲中的巨型冰塊如彗星般撞向行星。

(這位中文記者不知道彗星的暱稱「髒雪球」…雲特雲是彗星的產地)

有古生物學家指地球約每隔二千六百萬年便會遭受浩劫，相信彗星撞擊便是引致這些災難

的原因。



又，該則中文新聞應該譯自以下這篇英文新聞

http://ppt.cc/CFam

Invisible star 'shooting comets at Earth'
By Paul Sutherland at The Sun From: NewsCore March 12, 2010

The dinosaurs may have died because an invisible brown dwarf star is throwing
snowballs at us / AFP Source: AFP
Brown dwarf could have caused mass extinctions
Star is invisible and a long way away
But heat-seeking telescope may find it

AN invisible star responsible for the extinction of dinosaurs may be circling
the Sun and causing comets to bombard the Earth, scientists said.

The brown dwarf - up to five times the size of Jupiter - could be to blame
for mass extinctions that occur here every 26 million years, The Sun reports.

The star - nicknamed Nemesis by NASA scientists - would be invisible as it
only emits infrared light and is incredibly distant. Nemesis is believed to
orbit our solar system at 25,000 times the distance of the Earth to the Sun.

As it spins through the galaxy, its gravitational pull drags icy bodies out
of the Oort Cloud - a vast sphere of rock and dust twice as far away as
Nemesis.

These "snowballs" are thrown towards Earth as comets, causing devastation
similar to the asteroid that wiped out the dinosaurs 65 million years ago.

Now NASA scientists believe they will be able to find Nemesis using a new
heat-seeking telescope that began scanning the skies in January.

The Wide-Field Infrared Survey Explorer - expected to find a thousand brown
dwarf stars within 25 light years of the Sun - has already sent back a photo
of a comet possibly dislodged from the Oort Cloud.

Scientists' first clue to the existence of Nemesis was the bizarre orbit of a
dwarf planet called Sedna. Scientists believe its unusual, 12,000-year-long
oval orbit could be explained by a massive celestial body.

Mike Brown, who discovered Sedna in 2003, said: "Sedna is a very odd object -
it shouldn't be there.

"The only way to get on an eccentric orbit is to have some giant body kick
you - so what is out there?"

Professor John Matese, of the University of Louisiana at Lafayette, said most
comets come from the same part of the Oort Cloud.

He added: "There is statistically significant evidence that this
concentration of comets could be caused by a companion to the Sun."




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