This image, taken by the Hubble Space Telescope on December 14th, 1990, is enhanced to show cloud activity in the martian atmosphere.  This is also the best image of Mars that the Hubble took during that apparition.

Below is the full set, taken just after opposition, with Mars subtending about 18 arc seconds.   The series began on December 13th and followed the planet as it rotated.  The first set was a disaster - the image bounced all over the place from frame to frame, and all of the shots partially missed and some totally missed the planet.  This is the image farthest to the right in the set below (given this half image, I went from right to left for aesthetic reasons).  The middle image, most familiar in oft-copied scans of an over-processed press release image, shows the Syrtis Major hemisphere. However, there still seems to be a lot of jitter, and the frames do not seem sharp.  I at first blamed spherical aberration, but since after deconvolution it still didn't look as good as later pre-repair images, I think that there are other problems.  In the left-hand shot, which is the same as the image above, the image quality is excellent.

One reason I posted these images that enhance the hazes is that the original Wide Field/Planetary Camera took much more time between frames than WF/PC2 and later cameras, so planetary rotation is a serious problem.  I reprojected the images to compensate, but the edges aren't perfect - the enhanced hazes help to mask that.  Another version of these images will eventually be posted.

Processed images Copyright Ted Stryk, Raw Data Courtesy NASA/STSCI