How Many Light Years Away Is Mars? Distances of the Red Planet Revealed

By Donna Bellevue , Feb 23, 2017 02:02 AM EST

After NASA's exciting exoplanet discoveries, we take a look at how many light years away is Mars from Earth. However, we need to first understand what a light year entails. Since stars other than our sun are so incredibly far away, astronomers speak of their distances in terms of light years instead of kilometers or miles to avoid ending up with impossibly huge numbers.

The 20th century astronomer and author Robert Burnham Jr. devised this ingenious way to indicate the distance of one light-year to easily express the distance scale of the universe. By introducing light year, describing the distance of stars and planets become more understandable. He relates the light-year to the Earth-sun distance as the astronomical unit (AU).

To understand how many light years it takes to Mars, the ideas is that one AU is about 93 million miles (150 million km), or a bit more than 8 light-minutes in distance. To illuminate how fast that is, light travels at an incredible 186,000 miles (300,000 km) per second. If you could travel at the speed of light, you would have circled the Earth’s equator 7.5 times in just one second, the EarthSky reports.

To simplify, a light-year is the distance light travels in one year wherein a light-second is the distance light travels in one second, or 7.5 times the distance around Earth’s equator. Just multiply the number of seconds in one year by the number of miles or kilometers that light travels in one second, and you'll get one light-year is about 5.88 trillion miles (9.5 trillion km).

According to, it takes less than one light year away to travel from Mars to Earth. However, the exact distance changes moment to moment since both Earth and Mars orbit the Sun. That's why there are calculations of short and long distances between the two planets with the average distance of 140 million miles (225 million km).

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