Moon and Mars

The seasons are changing on Mars. Today is the first full day of winter in the planet’s northern hemisphere. The new season follows what turned out to be a nasty autumn.

Mars has seasons for the same reason Earth does: The planet is tilted on its axis. As it orbits the Sun, the north and south poles take turns dipping toward the Sun. As a result, the northern and southern hemispheres take turns getting more and less sunlight — creating seasons.

The seasons are more complicated than those on Earth, though. That’s because Mars follows a more lopsided orbit around the Sun. The planet is closest to the Sun during northern winter, and farthest during summer. So summers and winters are milder in the north than in the south.

The changes in sunlight can trigger big dust storms. As the surface warms, it creates wind currents that stir up the powdery dust that covers much of Mars.

That’s just what happened back in May. Just days after the spring equinox on Mars, a storm whirled to life in the northern hemisphere. By the end of June, it encircled the entire planet. Rovers on the surface saw day turn almost to night. The Sun vanished from view, and the sky turned dark red.

It’s taking months for the dust to settle out of the atmosphere — creating a hazy winter in the northern hemisphere.

Look for Mars to the left of the Moon as darkness falls this evening. It looks like a bright orange star. It’ll be even closer to the Moon as they set, after midnight.

Script by Damond Benningfield