An amateur astronomer in West Chester, Penn. took a picture of a curious Martian cloud several nights ago that has the community of Mars observers abuzz. Wayne Jaeschke photographed Mars on the evening of March 19 with a 14-inch telescope and noticed the plume after processing his images.

When I first started processing these images,I was ready to smash my telescope because of the terminator "defect!". But thanks to Wayne's great work my scope was spared. This "cloud" on the morning limb is truly extraordinary. Evening limb orographics are never this high. This feature reminds me of the SL-9 impact plumes that were carried over the limb of Jupiter in July of 1994. Moreover,it is prominent on the red as well as the blue channel. At the risk of sounding daft,perhaps it is of impact and not meteorological origin. I agree with Roger Venable that one must take the terminator into account when determining the height of this cloud. However Mars is 98.4% illuminated now,so the terminator effect is minimal -- the cloud still has dramatic altitude. Furthermore I have never seen a cloud like this even when the Tharsis orographics are on the evening terminator during perihelic apparitions. Who said that Mars is boring this year??