A NASA probe has sent back photographs of what appears to be trees on the planets surface. The images appear to show rows of dark conifers sprouting from dunes and hills on the planet surface. But the scene is actually an optical illusion. The photographs actually show sand dunes coated with a thin layer of frozen carbon dioxide, or dry ice, less than 240 miles from the planets north pole. The trees are really trails of debris caused by landslides as ice melts in Marss spring. You can even see a cloud of dust, just to the left of centre of the picture, where an avalanche is caught happening. The photograph was taken from orbit around Mars by HiRISE, the most powerful camera sent to another planet. NASAs Candy Hansen told The Sun: The streaks are sand, dislodged as ice evaporates, which slide down the dune. At this time of the Martian year the whole scene is covered by CO2 frost. Last month Nasa announced a new telescope had detected five planets outside the solar system. The observatory, which was launched last year to find other Earths, made the discoveries in its first few weeks of science operations. Although the new worlds, called exoplanets, are all bigger than Neptune, Nasa said their discovery showed that the planet hunting telescope was working well. Telegraph