Scientists from the European Space Agency (ESA) have detected a massive alien comet heading towards our star, the Sun, using the SOHO (Solar and Heliospheric Observatory) satellite. The 6-kilometer wide space ice mass, called 96P/Machholz 1, originates from somewhere outside of our Solar System. It has been tracked and monitored by the SOHO spacecraft as it speeds towards Mercury‘s orbit, leaving behind an icy trail.
The composition of comets
The comet’s tail is primarily composed of gas, which is heated by solar radiation. An analysis in 2008 found that 96P/Machholz 1 contains less than 1.5% of the expected levels of cyanogen (a carbon atom bound to nitrogen), leading astronomers to conclude that it could be an intruder from another star system. Its journey to the Sun may now reveal further secrets.
“96P is a very atypical comet, both in composition and behavior, so we never know exactly what we might see” said Karl Battams, an astrophysicist at the Naval Research Lab in Washington. “We hope to get some wonderful science out of it and share it with everyone as soon as possible”. David Machholz first discovered the eponymous comet in 1986 using a homemade cardboard telescope. Most comets that fall towards the Sun tend to be smaller than 10 meters in width and therefore dissolve when they approach our star.
However, Machholz 1’s giant size seems to protect it from complete evaporation. Its closest point to the Sun occurred on Tuesday, January 31st, when it was three times closer to Mercury.
How did it get to our Solar System?
The comet could have invaded our Solar System after being expelled from its original star system by the gravity of a giant planet. Then, after a significant amount of time wandering through space, an encounter with Jupiter could have bent the alien comet ‘s trajectory, now directing it towards the Sun.
Other theories suggest that the comet may not be alien. It may have formed in poorly understood regions of the Solar System, or its cyanogen has been expelled from repeated trips around the Sun. SOHO has identified over 3,000 comets since its launch in December 1995, although the spacecraft’s main mission is to observe the Sun.