New mystery discovered regarding active asteroid Phaethon

[Judi Lynn]

June 29, 2018, National Astronomical Observatory of Japan

Based on a new study of how near-Earth asteroid Phaethon reflects light at different angles, astronomers think that its surface may reflect less light than previously thought. This is an exciting mystery for the recently approved DESTINY+ mission to investigate when it flies past Phaethon.

The way an object reflects light depends not only on its albedo (the percentage of light it reflects) but also on the illumination angle. One particular effect that scientists are interested in is how the polarization changes when sunlight reflects off the surface of an asteroid. Scientifically, light is referred to as electromagnetic waves; the waves create changes in the electric and magnetic fields. The directions of these changes can either be random or aligned. When the electromagnetic effects of light are aligned, the light is said to be polarized.

An international team, including astronomers from the National Astronomical Observatory of Japan (NAOJ), Seoul National University, Chiba Institute of Technology, and other institutes, used the 1.6-m Pirka Telescope at Nayoro Observatory in Hokkaido Japan to observe the near-Earth asteroid (3200) Phaethon. They studied the changes in the polarization of the light it reflected at many different illumination angles. The results show that at some angles, the light reflected from Phaethon is the most polarized light ever observed among small bodies in the Solar System.

Discovered in 1983, Phaethon has been shown to be the parent body of the Geminid meteor shower. Most meteor-shower parent bodies are comets, but Phaethon doesn't show typical cometary activity. Instead it is an active asteroid with confirmed dust ejections. It also has a surprisingly blue color. The fact that its reflected light is strongly polarized is one more mystery surrounding this curious asteroid

Read more at: https://phys.org/news/2018-06-mystery-asteroid-phaethon.html#jCp

[Crutchez_CuiBono]

1. Sweet!!

The main asteroid of The Geminids!