Comet 96P/Machholz is making a very close approach to the Sun, the orbit places the perihelion – the closest approach to the sun – on Feb. 7th at just 0.12 AU.

Here’s an animation from the SOHO spacecraft with the comet approaching the Sun:

This comet just might survive its encounter with the Sun because it is 6.4 km across, which is larger than most comets that approach the Sun, which come in at about 10 meters.

This comet has a period of 5.29 years and was discovered in 1986, so it has already had several encounters with the Sun. This comet is also unique because its chemistry shows that it is both carbon-depleted and cyanogen-depleted, which is uncommon for comets that originate within the solar system.

Several possibilities could explain the comet’s unusual composition:

  • One theory is that 96P didn’t come from our solar system, but instead escaped another star’s gravity. This means that the star’s proto-planetary disk (the disk of debris from which planets are thought to form) could have had less carbon, making all carbon-based compounds less common.
  • Another idea is that 96P formed inside our solar system, but way out in a colder, more extreme environment compared to other comets.
  • A third option is that 96P started as a carbon-depleted comet, but got altered when it was heated up, causing cyanogen to decrease too. While no other comet has changed due to heat from the sun, 96P orbits close to Mercury every five years.

The comet makes its closest approach to the Sun on January 31, so we’ll know soon whether it survives this encounter with the Sun.