Comet 96P/Machholz or 96P/Machholz 1[1] is a periodic comet discovered on May 12, 1986 by Donald Machholz in Loma Prieta, California.[2][1] It entered SOHO's field of view in 1996, 2002, and 2007, seen in both LASCO C2 and C3.[3][1] On April 3, 2007, it again reached perihelion, at a predicted magnitude +2.[4] It may have been visible very early in the morning. It entered SOHO's LASCO C3's field of view early April, from April 2 to April 6, peaking in brightness on April 4, 2007[5]. Its coma was substantially smaller than the sun in volume, seen in SOHO.
The comet's orbit is extremely eccentric, coming closer to the Sun than Mercury. The orbit corresponds to the Arietids and the Marsden and Kracht Comet groups.[6]
Unique composition
Machholz 1 has a unique chemical composition compared to other comets. Spectrographic analysis of the comet's tail revealed it also has far fewer carbon molecules than the 150 other comets which were also analyzed. Other comets typically have 72 times as much cyanogen than Machholz 1. A leading hypothesis for the difference is that Machholz 1 comes from outside the solar system and was captured by the Sun.[7] Other possibilities are that it formed in an extremely cold region of the solar system (such that most carbon gets trapped in other molecules) or that, given how close it approaches the Sun at perihelion, repeated baking by the Sun has stripped most of its cyanogen.
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