On May 22, the sun, the Earth, and the planet Mars will line up for a once-in-two-years treat called "the opposition of Mars." It's a chance to see the red planet in big, bright, detail.
This event is called an "opposition" simply because Mars will be directly opposite the sun in orbit. It's special for two reasons.
- When celestial objects are directly opposite the sun, they appear brighter in the sky. Mars will shine much more brightly than it usually does.
- The opposition also will occur at a point where Earth and Mars are nearing their closest approach to one another. This makes Mars appear bigger in the sky than it normally would.
You can look for this big, bright, and beautiful Mars rising in the east right after the sun sets in the west. It will be the ruddy-colored object near the star Antares. "Then, after staying up in the sky the entire night, Mars sets in the west just as the sun rises in the east," NASA explains.
Mars will be brightest during the opposition, but the next few weeks will be a great time to observe the planet regardless. That's because Mars will make its closest approach to Earth on May 30. Until then, it will appear to increase in size in our night sky.
The opposition occurs every 26 months, and there are some lucky years when it coincides closer to when Earth and Mars are at their nearest. That provides a particularly spectacular show (Mars is both as big and as bright as it gets).
In 2003 Mars had its closest opposition since prehistoric times, according to Earthsky. That record will stand until the year 2287.
During opposition, Mars will be visible with the naked eye. But a basic backyard telescope will reveal details of its surface that are harder to see at other times, like its polar ice caps.
(You can also watch a live stream of the opposition here, via the astronomy streaming website Slooh.)
You might also look out for the "blue moon" this weekend — an extra full moon within a season. That the two celestial shows are happening so close to one another is a coincidence. Make of them what you will. I'm buying lottery tickets.