Comet Lulin was discovered on July 11, 2007, by the duo of Ye Quanzhi and Lin Chi-Sheng. A non-periodic comet, Lulin appears to be greenish in color; courtesy, the presence of gases like cyanogen and diatomic carbon, which produce a green glow when illuminated by sunlight in the vacuum of the space. Officially designated as C/2007 N3 (Lulin), it is also known as the 'Comet of Cooperation' in China and Taiwan, as the two individuals involved in its discovery, were from these two countries.
This comet was first photographed by Taiwanese astronomer, Lin Chi-Sheng on July 11, 2007, while he was working on the Lulin Sky Survey Project (LUSS) at the Lulin observatory in Nantou, Taiwan. (The Lulin Sky Survey Project aims to identify the numerous small objects in the solar system, particularly those that pose possible hazards to our planet.) Lin used a 16-inch telescope to photograph this comet, which was initially assumed to be an asteroid. A few days later, Ye Quanzhi, a 19-year old student of meteorology from Sun Yat-Sen University, recognized this comet while going through Lin's photographs. Its status of being a comet was confirmed after the presence of coma, the nebulous envelope around the nucleus of the comet, was noticed. Both, Lin and Quanzhi were accredited with the discovery of this new comet. As it was first noticed from the Lulin Observatory, it was named Lulin.
Comet Lulin was seen in the Libra constellation from January to March 2009. In January, it was getting brighter and could be seen just before dawn; while in February, the brightness reached its peak. Eventually, in March, it started to fade as it went farther away from the Earth.
While it was approaching the Earth, it had a typical tail pointing away from the Sun, as well as an 'anti-tail' which was directly pointing towards the Sun. While it was assumed that this anti-tail was observed only in photographs, some observers reported that it was visible even from a telescope in February 2009.
According to Brian Marsden, an astronomer at Smithsonian Astrophysical Observatory, Massachusetts, this comet's closest approach to the Sun was on January 10, 2009 when it reached a distance of 113 million miles from the solar surface. He noticed that the comet was moving in a retrograde orbit that is near-parabolic. On February 24, Lulin came the closest to the Earth, at a distance of 0.41 AU, or 38 million miles to be precise.
On February 4, 2009, a team of Italian astronomers, under the leadership of Ernesto Guido, witnessed a strange phenomenon. While photographing the comet with a remotely controlled telescope in New Mexico, they saw that its tail suddenly disconnected. Ernesto attributed this odd phenomenon to magnetic disturbance of the solar wind hitting the comet. Earlier, this had been observed with Comet Encke, when coronal mass ejection occurred, due to such magnetic storms.
Photographs taken by NASA's Swift Gamma-ray Explorer satellite in ultra-violet and X-rays show that Lulin is shedding 800 gallons of water every second. Observations by NASA also revealed that the surface material of the comet was burning away due to the Sun's heat.
This sighting of Comet Lulin was a once-in-a-lifetime opportunity for the whole world, as there is no possibility of this comet returning to the inner solar system; at least, not for the next thousand years.