Mars at Opposition this May

Mars is easy to see and quite bright this May, because it is nearing opposition - when our two planets are at their closest points. The very first Stars Over Peoria post was about this event when it happened about two years ago. Read on to learn what is happening and how to see Mars! 

Mars in natural color by Mars Express. Image Credit

As seen in our sky, Mars is directly opposite of the Sun on May 22 – it will rise at sunset and be visible all night. Astronomers call this occurrence the opposition of Mars. It happens once every 26 months, which is the amount of time it takes the Earth to loop back around the Sun to line up with Mars again as both planets orbit our star. 

The Sun, Earth and Mars are lined up on May 22, meaning Mars will appear to rise as the Sun sets. Image Credit: Solar System Scope

Our planet, in its smaller, faster orbit, will pass between the Sun and Mars. This means our two planets will be relatively close together.  The Red Planet will only be 46.78 million miles away, so it will appear a bit larger in our sky than usual, and it will reflect more sunlight back at the Earth, making it very bright. Because the planets' orbits are not perfect circles, some oppositions bring the planets closer than others. This one brings Earth and Mars 10 million miles closer than the last opposition. Our two planets can be 249 million miles away at their farthest points!   

Mars rises as the Sun sets on May 22, and Saturn follows shortly after. Image Credit: Stellarium and me.

 

It is especially easy to spot Mars from Peoria right now. Look to the east after the sun goes down for what looks like a very bright red star. Bright Saturn will be nearby, and on May 22, the Moon will be along for the show as well! Because Mars is at opposition, for several weeks it will be brighter than all the nighttime stars (about the same brightness as the planet Jupiter, which can be spotted high in the sky at sundown). Mars is close to the red star Antares right now, but it is easy to tell them apart because Mars is so much brighter. If you have access to a telescope, now would be a good time to train it on Mars. The planet will be so close that you might be able to see the ice cap on the Northern pole.

Because Earth is passing Mars, Mars will appear to move in the opposite direction in the sky as it usually does. Usually, night by night, Mars appears to move a little bit from west to east of where it was the night before. When we pass Mars, it appears to move in retrograde, or from east to west. You can track the progress of Mars' retrograde motion by watching it in reference to the stars in Scorpius the Scorpion. 

Tonight, Mars will be near the middle star in the Scorpion's head.

 

At the end of May, Mars will be moving out of Scorpius into Libra, to the west of where it is now.

By mid-June, Mars will be in Libra. It hangs out in this general area for a bit, and then will appear to move to the east again.

By August 10, Mars is back in Scorpius, but below the middle star.

Retrograde motion is one of the things that confused early astronomers who tried to prove that the planets and Sun orbited the Earth. If you would like to learn more about what is happening to cause these strange patterns, check out this nice video:

 

Have fun watching Mars, Jupiter, and Saturn in the sky this summer! Remember, you can always learn what's happening in the sky and the latest news from space at the Dome Planetarium at the Peoria Riverfront Museum. Follow us on Facebook and Twitter for daily updates!