Four Comets at Once

Four comets are now visible in STEREO-A's Heliospheric Imager 2, although you'll have to look very closely to see them all! If you look carefully enough you can see comets ISON, Lovejoy, Encke, and now Nevski. These movies were supplied by Alan Watson, one of a group of amateur comet watchers accessing data from STEREO and SOHO.

Processed images from STEREO-A's HI2 imager, with labels showing the approximate locations of comets ISON, Lovjoy, Encke, and Nevsky from Nov. 10-14, 2013. The comets are faint and can be seen moving against the stationary field of stars. The frames are run forwards and then backwards in time to make the comets easier to spot. Also in the movie is M45 (the Pleiades star cluster). The bright features with the vertical lines through them are planets. The Sun is out of the field of view to the right and a coronal mass ejection (CME) can be seen moving through the images.

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The same movie using running difference imaging in which each image is subtracted from the one following it. This makes it easier to see faint changes.

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A close up showing Comet ISON's tail interacting with the CME

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STEREO's Comet ISON page

• http://stereo-ssc.nascom.nasa.gov/comet_ison/