Astronomers Identify Rare Comet-like Binary A steroid

Aadil Islam ‘21

This artwork shows the orbital path for each of binary asteroid 288P’s component asteroids. The shaded white area represents the sublimation of water, a comet-like characteristic. Image Source: Wikipedia Commons

This artwork shows the orbital path for each of binary asteroid 288P’s component asteroids. The shaded white area represents the sublimation of water, a comet-like characteristic.Image Source: Wikipedia Commons

Spotting a shooting star in the sky is an infrequent spectacle in itself, yet a German-led group of astronomers appears to have doubled their fortune this past year. In September of 2016, NASA’s Hubble Space Telescope was used to spot 288P, an unusual system of two asteroids orbiting each other, originating from the solar system’s asteroid belt (1).

Asteroids and comets have several important distinctions; the former consists of rocky material and metals, whereas the latter is made of rocky material, ice, and dust. Every comet has a coma, a bright area of burning gas and dust surrounding the nucleus, as well as a tail, which always points away from the sun because of radiation pressure and solar wind.

From Earth, it is difficult to see with the naked eye the turbulent atmosphere over a comet’s surface. Consider the findings of Jessica Agarwal, leader of the astronomy team and scientist at the Max Planck Institute for Solar System Research, who reports about 288P, “We detected strong indications of the sublimation of water ice due to the increased solar heating — similar to how the tail of a comet is created.”

Sublimation is the process of turning a solid directly into a gas without passing through the liquid state, requiring extreme temperature change. Thus, in the presence of solar heat, comets form their distinct gaseous tails.

After analyzing many of 288P’s characteristics (two-component structure, highly eccentric orbit, etc.), the team dated the binary asteroid at approximately 5000 years of age. One theory suggests that 288P originally broke in half from a single asteroid due to high rotation speed, and that the halves separated further due to opposing forces caused by sublimation on the surfaces.

The unlikely finding of this comet-like binary asteroid poses some doubt, as 288P could have been a coincidental formation and possibly the last of its kind for quite some time. Agarwal herself concludes, “We need more theoretical and observational work, as well as more objects similar to 288P.” Analysis of comet origin and evolution may yield clues for scientists on how the Solar System formed. This makes bodies like 288P all the more intriguing and mysterious, considering all the untold truths they may hold.

References:

  1. ESA/Hubble Information Centre. (2017, September 20). Unique type of object discovered in our solar system. ScienceDaily . Retrieved October 1, 2017 from www.sciencedaily.com/releases/2017/09/170920144724.htm
  2. ESA/Hubble Information Centre, & Calçada, L. (2017, September 20). The binary asteroid 288P (artist’s impression) [Digital image]. Retrieved October 1, 2017, from https://en.wikipedia.org/wiki/Binary_asteroid#/media/File:The_binary_asteroid_288P_(artist’s_impression).jpg
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