An instrument on one of the two new STEREO spacecraft captured an unprecedented view of the brightest comet of the last 40 years. Positioned out in space ahead of the Earth as its orbits the Sun, it had a ringside seat on the very brilliant Comet McNaught. The SECCHI/HI-1A instrument on the NASA STEREO-A (Ahead) spacecraft took the frames for this spectacular video during the period of January 11- 18, 2007. (The still shows the comet on January 17.) The full field of view of the HI instrument (a wide-angle sky imager) is centered at about 14 degrees from Sun's center and is 20 degrees wide. The comet tail is approximately 7 degrees in length and shows multiple rays.
The image shows the comet tail in spectacular detail, especially once the bright comet head left the field of view and stopped saturating the images. These images are very likely the most detailed images ever taken of a comet while it is very close (0.17 Astronomical Units, which is even closer than Mercury) to the Sun. It has been described by one experienced comet scientist as "one of, if not the most, beautiful uninterrupted sequence of images of a comet ever made."
Also visible in these movies is Venus (bright object left of center at the bottom) and Mercury (appears from the right later in the sequence). Even their brightness creates saturation streaks on the very sensitive imager.