As soon as darkness falls this evening, watch for the red planet Mars to pop out in the vicinity of tonight’s waxing gibbous moon. The moon and Mars stay out tonight until the wee hours tomorrow.
In many respects, Mars is the planet most like Earth. The tilt of the rotational axes and the length of the day are close to the same on both worlds.
The Earth’s orbital axis is tilted some 23.4o out of vertical to our orbital plane. That is why we have seasons. On the solstices, Earth’s axis tilts maximally relative to the sun, and on the equinoxes, the Earth’s axis neither tilts toward nor away from the sun.
The tilt of the Earth’s axis gives us the seasons
Image credit: Wikimedia Commons. Click here for a larger version
On Mars, the rotational axis is only a slight bit more titled, at 25.2o out of vertical to its orbital plane. Mars’ rotational axis – like that of Earth – is tilted most greatly toward the sun on the solstices, and not at all on the equinoxes.
The Earth rotates full circle relative to the sun in about 24 hours, whereas Mars does so in a period of about 24 hours and 40 minutes. Because the rotational period and axial tilt are similar on both planets, the seasonal change of daylight for any given latitude is also comparable.
But there is one major difference between Earth and Mars. Mars, the fourth planet outward from the sun, takes nearly two Earth-years to circle the sun. That means a season on Mars lasts nearly twice as long as it does on Earth.
Use the waxing gibbous moon to find the red planet Mars tonight, the world that’s most like Earth in the solar system!orbital plane, rotational axis, waxing gibbous moon, the red planet Mars tonight, the red planet Mars, wikimedia commons <BR/>