Mars and Saturn

StarDate: August 21, 2014

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Summer still has a month to go here in the northern hemisphere of Earth, but the northern hemisphere of Mars is already seeing the cooler days of autumn. The season arrived earlier this week. It’ll last about five months — shorter than any other Martian season.

Like Earth, Mars has seasons mainly because it’s tilted on its axis. It’s summer in the north when the north pole tilts most directly toward the Sun, and winter when the south pole aims at the Sun.

But the Martian seasons are exaggerated by the planet’s orbit. While Earth’s distance from the Sun varies by only about three million miles, the distance from Mars to the Sun varies by 26 million miles.

Mars is closest to the Sun when it’s winter in the northern hemisphere, and farthest when it’s summer, so that half of the planet sees mild winters and summers. The south, on the other hand, has short but warm summers and long, cold winters. And the longest season of all on the Red Planet is northern spring, which stretches across almost 200 Earth days — a long time to thaw out after the Martian winter.

And Mars is staging a nice encounter with Saturn in the evening sky. Mars looks like a bright yellow-orange star. Slightly brighter Saturn is close to the upper left of Mars tonight. Mars will swing beneath Saturn over the next few nights, then pull away from it through the rest of the summer and into autumn.

We’ll talk about an even brighter encounter in the morning sky tomorrow.

Script by Damond Benningfield, Copyright 2014


For more skywatching tips, astronomy news, and much more, read StarDate magazine.

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