How Long Does it Take Mars to Orbit the Sun?

by Jerry Coffey on November 4, 2009

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How Long Does it Take Mars to Orbit the Sun?

Photo of Mars


“How long does it take Mars to orbit the Sun?”. Yet another great question from our Universe Today readers. Mars takes 686.971 Earth days to orbit the Sun. That means that one Martian year is equal to 1.88 Earth years.

Now that you know how long the Martian year is, would you like to know if the planet experiences seasons like Earth does? Yes, Mars has all four seasons that the Earth does, but, since the year is longer on the planet, the axial tilt is different, and Mars has a more eccentric orbit than Earth, the seasons are not the same length as each other nor are they the same in each hemisphere. In the northern hemisphere spring is the longest season. In the northern hemisphere of Mars the seasons break down like this: Spring…7 months, Summer…6 months, Fall…5.3 months, and Winter…just over 4 months. In the south seasons not exactly the same length as in the north, but they are similar; however, the temperatures can be as much as 30 C warmer.

The orbital path that Mars follows is highly eccentric. As the Earth and Mars move along their orbits, there are certain points when the planet’s are closer together than others. The close approaches occur roughly every two years and facilitate the launching of spacecraft. Even then it takes roughly eight months for a spacecraft to reach the Red Planet. The amount of time spent in transit is one of the biggest obstacles to manned exploration of the planet. In 2009, a company named Ad Astra Rocket Company tested a plasma booster called VASIMR (Variable Specific Impulse Magnetoplasma Rocket) that can make the trip on much less fuel and at faster speeds, possibly cutting the trip to 39 days. Initial tests of the rocket have been successful and there scheduled to be tested on the International Space Station in 2013.

Earlier it was mentioned that Mars followed a highly eccentric orbit. The orbit of Mars is the second most eccentric in the Solar System. Only Mercury’s orbit is more eccentric. At perihelion Mars is 206,655,215 km from the Sun and at aphelion it is 249,232,432 km distant. That is a variation of of just under 42,600,000 km. The average distance from Mars to the Sun (called the semi-major axis) is 228 million km. The orbit of a planet varies in relation to the gravitational influences of the bodies around it, so the eccentricity can change over time. As recently as 1.35 million years ago, Mars was in a nearly circular orbit.

There are hundreds more Martian facts to be discovered. Be sure to look NASA’s website over. You could even head on over to Astronomy Cast or Bad Astronomy.

We have written many articles about Mars for Universe Today. Here’s an article about a trip to Mars that might only take 39 days. And here’s an article about cool dunes on Mars.

If you’d like more information on Mars, check out Hubblesite’s News Releases about Mars, and here’s a link to the NASA Mars Exploration home page.

We have recorded an entire episode of Astronomy Cast that’s just about Mars. Listen here, Episode 52: Mars.

Sources:
http://science.nasa.gov/science-news/science-at-nasa/2000/interplanetaryseasons/
http://microgravity.grc.nasa.gov/education/rocket/mars.html
http://www.physorg.com/news174031552.html
http://www.nasa.gov/vision/space/travelinginspace/future_propulsion.html

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