The joint European Space Agency (ESA) and NASA Solar and Heliospheric Observatory (SOHO) spots new comets on a regular basis, but it has just found one slightly different.
The unit’s Large Angle and Spectrometric Coronagraph Experiment (LASCO) has found a rare type of comet called a periodic comet. Periodic comets are ones which fly by the Sun at regular intervals. While other documented comets are believed to be periodic, this is the first time that one has been conclusively proven - something which requires it to have been seen revolving around the Sun more than twice, in which each incident is less than two hundred years apart.
First seen in September 1999, the new comet has an orbit that takes four years to travel around the Sun.