Remember that jelly-doughnut-shaped rock that seemed to appear out of nowhere on Mars last month?
NASA has now solved the mystery: Not only are there no doughnuts on Mars, but the rock didn't actually spontaneous show up.
The image above shows two pictures taken by NASA's Opportunity robotic rover 12 days apart ("sol" is the term for a day on Mars). The rock in question, dubbed Pinnacle Island, is only about 1.5 inches wide, but with nothing for scale in the image, you could be forgiven for imagining it to be much larger. Opportunity was exploring the rim of Endeavour Crater, a spot called Murray Ridge, where the rover has been all winter, when it rephotographed a spot it had just been -- and voila, jelly-doughnut rock. After all sorts of speculation among observers on Earth, Opportunity took a closer look at both the rock and path the rover had just traveled. That closer look enabled NASA scientists to deduce that the jelly-doughnut rock was only a fragment of a larger rock the rover had driven over.
According to the Jet Propulsion Laboratory, "Once we moved Opportunity a short distance, after inspecting Pinnacle Island, we could see directly uphill an overturned rock that has the same unusual appearance. We drove over it. We can see the track. That's where Pinnacle Island came from."
If you're disappointed Pinnacle Island didn't turn out to be more exciting, think about how amazing it is that we have a robotic rover on Mars that was designed to work for three months and is still working after more than 10 years.
Elsewhere in the Solar System: