A UV aurora found on Comet 67P/C-G
Using data from Europe’s now completed Rosetta mission to Comet 67P/C-G, scientists have detected evidence that the comet’s interaction with the Sun’s solar wind creates an aurora above the comet in ultra-violet wavelengths.
The data indicate 67P/C-G’s emissions are actually auroral in nature. Electrons streaming out in the solar wind – the stream of charged particles flowing out from the Sun – interact with the gas in the comet’s coma, breaking apart water and other molecules. The resulting atoms give off a distinctive far-ultraviolet light. Invisible to the naked eye, far-ultraviolet has the shortest wavelengths of radiation in the ultraviolet spectrum.
Labeling this phenomenon as an aurora is a bit of hype, as nothing is visible. However, the discovery does tell scientists how this comet’s coma, produced when the comet heats up in its approach to the Sun, interacts with the solar wind, and this in turn can teach them more about that wind, as well as other comets.
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Using data from Europe’s now completed Rosetta mission to Comet 67P/C-G, scientists have detected evidence that the comet’s interaction with the Sun’s solar wind creates an aurora above the comet in ultra-violet wavelengths.
The data indicate 67P/C-G’s emissions are actually auroral in nature. Electrons streaming out in the solar wind – the stream of charged particles flowing out from the Sun – interact with the gas in the comet’s coma, breaking apart water and other molecules. The resulting atoms give off a distinctive far-ultraviolet light. Invisible to the naked eye, far-ultraviolet has the shortest wavelengths of radiation in the ultraviolet spectrum.
Labeling this phenomenon as an aurora is a bit of hype, as nothing is visible. However, the discovery does tell scientists how this comet’s coma, produced when the comet heats up in its approach to the Sun, interacts with the solar wind, and this in turn can teach them more about that wind, as well as other comets.
Please consider donating to Behind the Black, by giving either a one-time contribution or a regular subscription, as outlined in the tip jar below. Your support will allow me to continue covering science and culture as I have for the past twenty years, independent and free from any outside influence.
Regular readers can support Behind The Black with a contribution via paypal:
If Paypal doesn't work for you, you can support Behind The Black directly by sending your donation by check, payable to Robert Zimmerman, to
Behind The Black
c/o Robert Zimmerman
P.O.Box 1262
Cortaro, AZ 85652
Astronomers were surprised by Chandra, the X-ray space telescope, producing a peak with no apparent explanation. Turns out that a comet passed by its field of view, but comets are frozen while x-rays come from high energy stellar events. They figured out that so do active comets in general. Heavy particles in the Solar wind do produce x-rays when they hit hydrogen in cometary comas. That was unexpected until the observation was made and the physics of it was had a looking to.
Since then Chandra takes beautiful x-ray images of comet’s comas, like these:
https://scx2.b-cdn.net/gfx/news/hires/2016/chandraobser.jpg