Etched in the geology of Mars are signs that it looked a lot more Earth-like billions of years ago. Its atmosphere was thicker. Some features look suspiciously like dried up rivers and even lakebeds. Perhaps, a long time ago, Mars had some form of life crawling on its surface. Or maybe not.
Astronomers are skeptics at heart.
They have been fooled by such supposed features before, and not too long ago. Early this century, some astronomers and most of the general public were absolutely persuaded that intelligent life existed on Mars right then and there. The evidence was pretty persuasive. Mars has polar caps like Earth. They show some signs that they are made of water.