No. 100: Jul-Aug 1995
A shadow and grid-like pattern.
"...the recent Phobos probe that the Russians sent to Mars in 1988 -- which met a mysterious and untimely demise -- recorded two quite mysterious Anomalies on the planet before contact was lost with the satellite. One was a strange shadow moving across the planet's surface (not a shadow of either of Mars' moons)! The other anomaly was a strange grid-like pattern at one location on the Martian surface; it was photographed with an infrared camera on Phobos 2, the first such instrument carried on a spacecraft sent to Mars." (Ref. 1)
The canals are still there -- in a shadowy way ! Commenting upon the theory that those Martian canals that keep showing up on plates made through terrestrial telescopes are only picture/film defects, D. Louderback points out that the:
"...canals are also showing up on CCD [Charge-Coupled Device] camera photos like the one taken by Donald Parker with a 12.5-inch reflector and shown on the cover of the Strolling Astronomer earlier this year. It clearly showed a pentagonal pattern of canals surrounding Elysium. It is almost certain that these were not a 'picture defect'!" (Ref. 1)
Searching for explanations, J. Gallagher has discovered that many of the prominent canals drawn by Lowell, Schiaparelli, et al, actually closely follow contour lines drawn on USGS maps of Mars from Viking data. It is quite possible, then, that the "canals" are really only elevational differences in Martian topography. (Ref. 2)
Global Cooling. The Hubble Space Telescope recently photographed Mars when the planet was nearly totally shrouded by high cirrus clouds. Mars is now cloudier than it has been for years. The reason for this is that the planet's average temperature has fallen by almost 20°C. What little water vapor exists in the atmosphere freezes out into cirrus clouds. Why has Mars cooled so drastically? Because the huge dust storms of the Viking years have mysteriously abated. Now, we have to explain why dust storms no longer envelope the planet! (Ref. 3)
Ref. 1. Louderback, Daniel; Letter, Strolling Astronomer, 37:131, 1994.
Ref. 2. Gordon, Rodger; Letter, Strolling Astronomer, 37:89, 1993.
Ref. 3. Kerr, Richard A.; "Hubble Glimpses a Hazy Day on Mars," Science, 267:1912, 1995.
Cross references. Modern sightings of canal-like lines on Mars can be found in The Moon and the Planets. Details here.