Mysterious cloud spotted on Mars Wayne Jaeschke Amateur astrophotographer Wayne Jaeschke captured this image of a "terminator projection" rising up from the edge of the Martian disk at about the 1 o'clock position on March 22. The inset photo is a 200 percent enlargement of the region around the projection. For more, check out Exosky.net, Jaeschke's website. Amateur astronomers are puzzling over a seemingly anomalous cloud that has shown up on images of Mars taken over the past few days. Is it really a cloud, or a trick of the eye? Does it really extend 150 miles up from the surface, as some of the observers suggest? And what churned up all that stuff, anyway? The amateurs and the pros will be trying to resolve those questions before the phenomenon fades away. "It's not completely unexpected," Jonathon Hill, a member of the team at the Mars Space Flight Facility at Arizona State University, told me today. But it's bigger than we would expect, and it's definitely something that our atmosphere guys want to take a look at. Hill and his colleagues will be looking at the area where the cloud was spotted using the Thermal Emission Imaging System, or THEMIS, which is one of the instruments on NASA's Mars Odyssey orbiter. "In the command upload we're preparing to send today, we've included observations that will hopefully capture some of these recent clouds," Hill wrote in an email. Our THEMIS camera on Mars Odyssey is capable of acquiring simultaneous visible and thermal infrared images, so our atmospheric researchers are pretty excited about the possibility of not only getting a good look at the cloud structures, but also their temperatures. THEMIS will be checking out heightened cloud activity around Mars' shield volcanoes as well as around the southern site spotted by the amateurs. Pictures from a camera on NASA's Mars Reconnaissance Orbiter, called the Mars Color Imager, or MARCI, might provide further clues about the southern cloud feature. And amateur astronomers are sending out the alert for observers to keep a close watch on the Red Planet over the coming days. There's been lots of buzz about the high-altitude cloud on Cloudy Nights and other online discussion forums for skywatchers. Sky & Telescope's Sean Walker says the puff of white was first noticed on March 20 by Wayne Jaeschke, an amateur astrophotographer from Pennsylvania. Since then, other observers have identified the feature in images going back as far as March 12. All sorts of hypotheses have been proposed: Could it be debris kicked up by a meteoric impact? Is it a huge weather system? Is it merely a funny kind of glint caused by a combination of lighting and atmospheric conditions? In an email, Jaeschke told me that the feature is "still there, although it has decreased in size over the past two days." "This has led some to believe that it was some sort of transient-type event," Jaeschke said. So it's crucial to make as many observations of the area as possible over the next few days. Wayne Jaeschke created this animated GIF image of Mars with the cloud coming into view on the upper right edge of the planet's disk. For more from Jaeschke, check out his Exosky website. Walker says the feature is currently well-placed for viewing from the Americas. He says it should show up on the edge of Mars' disk around 1:10 a.m. ET Saturday, and 39.5 minutes later on each succeeding night. Consult the photos above for guidance on where to point a medium-size telescope - keeping in mind that these images are inverted to appear as they would through a telescope, with south pointing "up." Arizona State University's Hill says the area in question is called Terra Cimmeria. Observation reports should be sent via email to Richard McKim, director of the British Astronomical Association's Mars Section. The linked website includes McKim's email address, as well as a picture of the chap. Solving this mystery - if it indeed turns out to be an honest-to-goodness mystery rather than a mere quirk - may require additional data from the big guns of the astronomy world. But in any case, the episode illustrates once again how much amateurs can contribute to uncovering the wonders of the cosmos. "When it comes to Mars, amateurs and professionals working together give you way more insight into ongoing processes, because with so many amateurs, you're continuously monitoring changes in the planet," Hill told me. They provide a perspective and a context that we don't usually get. More about amateur astronomy: Tip o' the Log to Sky & Telescope's Sean Walker and Kelly Beatty, as well as Wayne Jaeschke.