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Moon, Mars, and Saturn
The Moon and two planets form an arc in the early morning sky tomorrow. Orange Mars is to the right of the Moon, with golden Saturn to the lower left of the Moon.
Mars is considered one of the best possible homes for microscopic life in the solar system. That’s mainly because Mars appears to have a fair amount of water. There’s frozen water in the polar ice caps, and buried below the surface. There’s water vapor in the atmosphere. And there’s evidence that liquid water once formed rivers and lakes on the surface. That raises hopes that some liquid water could pool below the surface today.
One bit of evidence of present-day liquid water is dark streaks that appear on the inner slopes of craters during summer. Scientists have suggested that the streaks could be streams of salty water. They could burst out of underground pools when the weather warms up, and stay liquid long enough to flow to the crater floors.
A recent study, though, said that the streaks are more likely caused by flowing sand. The way the streaks flow down crater walls is similar to the way sand moves down slopes here on Earth. The researchers can’t explain why the streaks appear only in summer, though. They say the reason may involve smaller amounts of water, perhaps condensed from the atmosphere.
Even if the streaks are dry, though, it doesn’t completely dampen the hopes that water could support microscopic life on the Red Planet.
More about the Moon and Saturn tomorrow.