Green light for a close encounter: 'Jupiter-sized' comet to streak past Earth tonight
By Daily Mail Reporter
Last updated at 10:55 AM on 24th February 2009
We have known of its existence for only two years. But if you raise your eyes heavenwards over the next few nights, you might just catch a glimpse of the comet Lulin.
Glowing green, it will come within 38million miles of Earth, the closest it has ever been, and about the same distance away as Mars.
Lulin, photographed here by an astronomer in Arizona, was discovered by a 19-year-old student from a photo taken at Lulin Observatory-Taiwan, in 2007.
This stunning picture shows comet Lulin glowing green in the sky as it makes its closest approach to Earth
Comet Lulin is delighting amateur astronomers who are observing it using telescopes and binoculars
The spectacular comet will be visible to the naked eye over the next few nights.
Its colour comes from the gases that make up its Jupiter-sized atmosphere.
The stellar traveller is very active, shedding nearly 800 gallons of water each second on its journey around the Sun. That's enough liquid to fill an Olympic-sized swimming pool in less than 15 minutes.
Jets from the nucleus throw out cyanogen, a poisonous gas found in many comets, and diatomic carbon, which glow green when lit by sunlight.
It could be visible any time after dark.
Nasa said: 'Dark country skies will be required. But no one can say for sure. This appears to be Lulin's first visit to the inner solar system and its first exposure to intense sunlight. Surprises are possible.'
Andrew Read, from Leicester University, said: 'The comet is releasing a great amount of gas, which makes it an ideal target for X-ray observations.'
Astronomers using the Nasa Swift Satellite are tracking a spectacular comet as it closes in on Earth and sheds gas and dust from its vaporised ice. This combined view shows combined ultraviolet and X-ray images of the object
British astronomers from Leicester University will study the comet using the NASA Swift Satellite to find out more about its chemistry and gather clues about the origin of comets and the solar system.
Comet Lulin in January and February 2009. 
For the next few days, a newly discovered, green-tinted comet will be visible by the naked eye in most parts of the Northern Hemisphere. Comet Lulin, with the official designation of C/2007 N3, was discovered in 2007 and astronomers say that this is the first time it has visited our solar system and may well be the last.

As it makes its way around the Sun, an astonishing 800 gallons (3 m3) of water will evaporate from the comet every second. In each 15 minute period, it will shed enough water to fill an Olympic sized swimming pool. It will come within 38 million miles of Earth at its closest pass, making it visible to the naked eye and even clearer with binoculars or a telescope. 

The best viewing time for people living in the northern hemisphere is after midnight when Lulin will be at its highest point in the sky, or 40 degrees from the morning horizon. Current estimates peg the maximum brightness at 4th or 5th magnitude, which means dark country skies would be required to see it. No one can say for sure, however, because this is Lulin's first visit.

Astronomers from NASA and the United Kingdom will use the Swift Telescope to study the comet and its composition. Astronomers also say to see it while you can because this could be the first and only time it passes through our solar system. It's estimated that if it returns, it will not be for another 1,000,000 years.

"We won't be able to send a space probe to the comet, but Swift is giving us some of the information we would get from just such a mission," said Jenny Carter, at the University of Leicester in England, who is leading the study.

The comet was discovered using the Lulin Observatory in Taiwan by astronomers Ye Quanzhi and Lin Chi-Sheng.