This photograph, taken by HiRISE—the most powerful camera sent to another planet—from orbit around Mars, appears to show rows of dark “conifers,” sprouting on the surface of the Red Planet.
But the scene is an optical illusion. It’s a case of apophenia (seeing pattern in random data.)
In reality, they’re sand dunes, coated with a thin layer of carbon dioxide frost, in the process of melting, in a Martian spring. As the Sun shone, the dark grains in their interiors became more and more visible. The “trees” are streaks caused by black sand, cascading down from the top of a dune.
h/t: THE TELEGRAPH