Mars is dry, cold, and quiet. But that hasn’t always been the case. Billions of years ago it was much busier – and perhaps a comfortable home for life.

Mars has had three major geological ages. The oldest was the Noachian. It’s named for a large highlands region in the southern hemisphere. It began about 4.1 billion years ago, and lasted for 400 million years.

The solar system was still packed with big “leftovers” from the birth of the planets then. Many of them slammed into Mars, forming wide basins that are still visible today.

At the same time, giant volcanoes belched gases into the atmosphere. That trapped heat, making Mars much warmer. Clouds might have produced rain or snow. The precipitation carved rivers and filled lakes and maybe even a large ocean. Conditions could have allowed the formation of microscopic life.

At the end of that period, there were fewer impacts and less volcanic activity. Mars cooled off, and the water dried up. So Mars became quieter as the Noachian Age ended, and the next age began.

Mars is close to the right or upper right of the Moon early this evening. It looks like a fairly bright star. But it’s quite low in the sky, especially as seen from the northern half of the country, so you need a clear horizon to spot it. The star Spica, which is about twice as bright as Mars, stands to the upper left of the Moon. We’ll have more about Spica tomorrow.

Script by Damond Benningfield