Astronomy Practice Exam

What geological feature on Mars suggests it could have once supported life?

1. Craters

2. Volcanoes

3. Dried rivers

4. Sand dunes

The correct answer is: Dried rivers

The presence of dried rivers on Mars indicates that liquid water was once prevalent on its surface, an essential element for supporting life as we know it. These dried riverbeds, or valleys, suggest a history of flowing water, which implies that conditions may have been suitable for life forms to exist in the past. Water is a critical ingredient for the biochemistry of life, and the discovery of features that resemble ancient river channels strongly supports the hypothesis that Mars had a more hospitable climate in its past, potentially allowing for microbial life to thrive. The other geological features listed do not provide the same level of evidence for past habitability. Craters are signs of impacts and provide information about the planet's age but do not indicate past life conditions. Volcanoes can show geological activity but do not directly relate to the presence of liquid water required for life. Sand dunes indicate wind activity and surface processes but do not suggest liquid water or biological activity.