New Comet Found

There's a newfoundcomet closing in on the sun,and when it gets here in 2013,you may be able tosee it with your naked eye.

Astronomers stumbledupon the icy interloper on June 5 while searching for potentially hazardousasteroids（小行星）.Equippedwith the world's largest digital camera , the

University ofHawaii's Pan-STARRS team snagged a faint image of the odd object while it wasmore than 700 million miles away , between the orbits of Jupiter（木星）and

Saturn（土星）.

"Almosteverything we find is an asteroid,but this object was suspicious,"saidRichard Wainscoat,co-discoverer of the comet and an astronomer at theUniversity of

Hawaii."Unlike asteroids, which appear point-like in images,thetelltale sign that gave it away was its fuzzy appearance."

By March 2013 thecomet,named C/2011 L4(PANSTARRS),is expected to come within 30 million miles ofthe sun一closer even thanthe innermost（最深处）planet,

Mercury（水星）.

When the comet makesits closest approach to the sun,most of its ices will vaporize,adding to itshazy envelope of gas and dust and producing the familiar tail. This denser

envelope,or coma,should boost the comet to peak brightness,making it potentially visible to thenaked eye low in the western horizon just after sunset.

While there is nodanger of collision with Earth,preliminary calculations of the comet's orbitshow that this may be its first and final trip through the solarsystem."It may be

coming around thesun for the first and only time,only to be ejected from the solar system,neverto return,"Wainscoat said."Since we don't have a lot of data on it,wereally

don't know the orbitwell enough right now, and it will take up to two months of observations tofind out."

Astronomers believeC/2011 L4 may be a runaway from the Oort cloud（奥尔特云）,a reservoir of billions of hibernating（蛰伏）comets that orbits about 100,000 times

farther than thedistance between Earth and the sun.

The fact that it'sgoing around the back of the sun from our point of view may ultimately affectthe comet's visibility,but a lot will depend on how close the body actuallygets

to the sun.Also,whether the comet is north or south of the sun when it reaches peak brightnesswill determine which hemisphere on Earth gets the better view.C/2011 L4 will hitEarth in 2013.

A.Right

B.Wrong

C.Not mentiond