NASA's WISE satellite spots "horseshoe" asteroid

     LOS ANGELES, April 8 (Xinhua) -- NASA's Wide-field Infrared¹ Survey Explorer (WISE) has discovered a rare asteroid² that traces out a horseshoe shape relative to Earth, the Jet Propulsion Laboratory (JPL) said on Friday.

    Unlike most near-Earth asteroids³ (NEAs) that have eccentric, or egg-shaped, orbits that take the asteroids（小行星） right through the inner solar system, the new object has an orbit that is almost circular such that it cannot come close to any other planet in the solar system except Earth, JPL said.

    However, even though the asteroid rides around with Earth, it never gets that close, said JPL in Pasadena, Los Angeles.

    As the asteroid approaches Earth, the planet's gravity causes the object to shift back into a larger orbit that takes longer to go around the sun than Earth. Alternately, as Earth catches up with the asteroid, the planet's gravity causes it to fall into a closer orbit that takes less time to go around the sun than Earth, according to JPL.

    The asteroid therefore never completely passes our planet. This slingshot-like effect results in a horseshoe-shaped path as seen from Earth, in which the new object, designated 2010 SO16, takes 175 years to get from one end of the horseshoe to the other, JPL said.

    "The origins of this object could prove to be very interesting, " said Amy Mainzer of JPL, the principal investigator⁴ of NEOWISE, which is the asteroid- and comet-hunting portion of the WISE survey mission. "We are really excited that the astronomy community is already finding treasures in the NEOWISE data that have been released so far."JPL manages and operates the WISE for NASA's Science Mission Directorate, Washington.(本文由在线英语听力室整理编辑)

1 infrared   

adj./n.红外线(的)

参考例句：

• Infrared is widely used in industry and medical science.红外线广泛应用于工业和医学科学。
• Infrared radiation has wavelengths longer than those of visible light.红外辐射的波长比可见光的波长长。

2 asteroid   

n.小行星；海盘车(动物)

参考例句：

• Astronomers have yet to witness an asteroid impact with another planet.天文学家还没有目击过小行星撞击其它行星。
• It's very unlikely that an asteroid will crash into Earth but the danger exists.小行星撞地球的可能性很小，但这样的危险还是存在的。

3 asteroids   

n.小行星( asteroid的名词复数 )；海盘车，海星

参考例句：

• Asteroids,also known as "minor planets",are numerous in the outer space. 小行星，亦称为“小型行星”，在外太空中不计其数。
• Most stars probably have their quota of planets, meteorids, comets, and asteroids. 多数恒星也许还拥有若干行星、流星、彗星和小行星。

4 investigator   

n.研究者，调查者，审查者

参考例句：

• He was a special investigator for the FBI.他是联邦调查局的特别调查员。
• The investigator was able to deduce the crime and find the criminal.调查者能够推出犯罪过程并锁定罪犯。