Get ready, because on May 30 this year, Mars is going to make its closest approach to Earth since 2005. Contrary to what some online hoaxes might have you believe, though, this isn’t going to make Mars noticeably much bigger in the sky, but it’s still an interesting event.
Earth, as you may know, orbits the Sun at a distance of 149.6 million kilometers (92.9 million miles) once every 365.3 days. Mars, at its more distant location of 227.9 million kilometers (141.6 million miles), takes 687 days to orbit the Sun. As we orbit faster, this means we go through periods where we are first both on the same side of the Sun and then on opposite sides.
This month, Earth will begin to overtake Mars on the same side of the Sun, and thus the two planets will be at their closest point to each other in their orbits. This is known as opposition, when Mars, Earth, and the Sun are all in a line in that order. At its most distant, Mars is about 401 million kilometers (249 million miles) away. On May 30, Mars will be a mere 75.3 million kilometers (46.8 million miles).
Although this is pretty close, it can be closer, such as in 2005. And in August 2003, Mars was just 55.76 million kilometers (34.65 million miles) away, its closest approach for 60,000 years. It won’t be until the year 2287 that Mars comes that close again.
NASA/JPL-Caltech
While interesting, these close approaches also serve a useful purpose when it comes to space travel. To carry out missions to Mars, spacecraft will often launch in the windows of closest approach (every 26 months) to minimize the travel time needed to get to the Red Planet. In March this year, for example, Europe and Russia launched the first part of their ambitious ExoMars mission. In 2018, meanwhile, during the next window, SpaceX is planning to launch its first spacecraft to Mars.
As mentioned above though, this close approach often also draws up an old Mars hoax, where people claim it will be as big as the Moon in the sky. Don’t be fooled; Mars will continue to be a small, shining red dot.
It will appear brighter than usual, though, from May 18 to June 3. So make sure you look outside, and maybe download one of the many stargazing apps, to have a look as our nearest planetary neighbor pays us a visit.
If you miss this one, don’t fret though. Mars will come even closer in 2018, a distance of just 57.6 million kilometers (35.8 million miles).
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