A view of a Comet


This composite is a mosaic comprising four individual NAVCAM images taken from 19 miles (31 kilometers) from the center of comet 67P/Churyumov-Gerasimenko on Nov. 20, 2014. The image resolution is 10 feet (3 meters) per pixel.

Credit: ESA/Rosetta/NAVCAM

Data from NASA instruments aboard the ESA (European Space Agency) Rosetta mission have helped reveal that comet 67P/Churyumov-Gerasimenko has its own far-ultraviolet aurora. It is the first time such electromagnetic emissions in the far-ultraviolet have been documented on a celestial object other than a planet or moon. A paper on the findings was released today in the journalĀ Nature Astronomy.

On Earth, aurora (also known as the northern or southern lights) are generated when electrically charged particles speeding from the Sun hit the upper atmosphere to create colorful shimmers of green, white, and red. Elsewhere in the solar system, Jupiter and some of its moons — as well as Saturn, Uranus, Neptune, and even Mars — have all exhibited their own version of northern lights. But the phenomena had yet to be documented in comets.

Rosetta is space exploration’s most traveled and accomplished comet hunter. Launched in 2004, it orbited comet 67P/Churyumov-Gerasimenko (67P/C-G) from Aug. 2014 until its dramatic end-of-mission comet landing in Sept. 2016. The data for this most recent study is on what mission scientists initially interpreted as “dayglow,” a process caused by photons of light interacting with the envelope of gas — known as the coma — that radiates from, and surrounds, the comet’s nucleus. But new analysis of the data paints a very different picture.

Solar Wind

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.


    • Likely ALMOST all of them. It keeps them going for a long time. A lot of asteroids are packed gravel from what I’ve read. They wouldn’t survive one approach to the Sun.

  1. Dont know how to break this to you, but the Tower of London is on the SOUTH bank of the Thames.
    If you look at where the arrow is pointing, follow the bridge (Tower Bridge) over the river, and the Tower is that big white building.

    • It’s on the north bank, Robert. I was just there, not too long ago. But it’s not my graphic anyway and the idea was to give a perspective of how big the comet is.

      • Oops, my bad, was looking at my map upside down! Shows how long its been since I went “up east”. Pity the comet cant just drift down and land with a soft but very heavy FLUMP, it would eliminate about 90 percent of the twats that have ruined my country!

        • You don’t want it corkscrewing in through the atmosphere at 25,000 mph and taking out the island. But I am with you on a gentle FLUMP.

  2. I disagree about the Tower of London- I remember visiting and it’s on the north bank as shown in the picture. I remember the Tower being right at the tip of the arrow.

    • Yes, on the north bank. And Big Ben and Whitehall is on the north bank. I think that Lambeth Palace (headquarters to LSP) is on the south bank. Unless I’m completely turned around.

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