Mars is the world orbiting the sun one step outward from Earth’s orbit. Earth takes one year to orbit the sun once. Mars takes about two years to orbit once. The adjacent orbits of Earth and Mars are the reason Mars is one of the most fascinating planets to watch in our sky, and they’re the reason Mars is sometimes bright and sometimes faint. Mars is bright now … nearly as bright as it’s been in two years!
The image above shows Mars in late May, 2016. On May 22, Earth will pass between the sun and Mars.
The brightness of Mars in our sky depends on where our two planets are in orbit around the sun. Sometimes Earth is close to Mars, and sometimes we are far away.
We are relatively close – and Mars appears at its brightest in our sky for that two-year period – every time Earth passes between the sun and Mars. At this time, Mars appears at opposition – opposite the sun in our sky – rising in the east when the sun sets in the west.
Oppositions of Mars recur about every two years and 50 days. April 8, 2014, is the date Earth last went between the sun and Mars. Throughout 2015 – and in all years lacking a Mars opposition – Mars appears faint. In non-opposition years, Mars lies far across the solar system from Earth, at times hidden from our view by the sun itself.
Mars will be particularly close at the 2016 opposition because of another cycle … which makes some oppositions of Mars closer than others. To learn more, check out the chart below:
If you focus a bit on the chart above, you’ll see why Mars comes particularly close in May 2016 and will do so again in July 2018.
So some oppositions of Mars are closer than others. But, in general, Mars will be close and bright in our sky every two years for billions of years to come!
Mars is lovely to behold, and, in 2016, it’s near another planet on the sky’s dome, the planet Saturn. See the chart below.
Also see a video of Mars and Saturn in 2016.
Bottom line: Mars is bright when it and Earth are on the same side of the sun. It’s faint when it and Earth are on opposite sides of the sun. 2016 is a grand year for seeing Mars. The best months for Mars viewing in 2016 are May and June. But the planet remains bright throughout the summer of 2016. Watch for it!
Deborah Byrd created the EarthSky radio series in 1991 and EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. "Being an EarthSky editor is like hosting a big global party for cool nature-lovers," she says.