The northeastern United States is experiencing record-breaking cold weather, with temperatures 20 to 30 degrees below average, according to the National Weather Service. Those are temperatures so frigid that parts of Mars—a cold, desert planet—are actually warmer than certain spots in the U.S. But how does Mars’ climate compare to that of our home planet?
Overall, Mars is cold—its average global temperature is around -80 degrees Fahrenheit—and has a much thinner atmosphere than Earth. Because it has about a sixth of the pressure of Earth’s atmosphere, the planet doesn’t retain heat very long, causing temperatures to drop quickly.
“The temperature on Mars right near the surface, in the path of the Sun, is going to be a lot warmer than if you were to raise even five feet up. There might be a 15-20 degree temperature change between where your feet are and where your head is if you were standing on Mars,” Matthew Shindell, curator of planetary science and exploration, said. Temperatures also dip drastically from day to night because there is little to retain heat on the planet. The sand and rocks of Mars’ surface lose their heat quickly.
While we experience temperature drops like that here on Earth—Shindell compared it to how hot desert climates cool substantially after sundown—it happens on a much different scale on Mars. “The thinner atmosphere is the big game changer,” he said.
Like Earth, Mars spins on an axis tilted about 25 degrees from its orbital plane. Mars has no large satellite like the Moon, just its two small moons Phobos and Deimos. As a result, the tug of gravity from the Sun and the large planets causes a slow wobble in the tilt, or obliquity, of its axis. During periods of higher obliquity, the atmosphere is thicker, dust storms are more intense, and water now trapped at the poles moves to the equatorial region to form mountain glaciers. Many glacial landforms from the last time this occurred can still be seen on Mars.
There are other things to consider when comparing weather data, like the seasons of the respective planets and the locations where temperature is measured.
“Similar to the Earth, Mars is tilted on its axis. Right now its axial tilt is about the same as it is on Earth, which means that as the planet orbits around the Sun, you’re having the same type of seasons on Mars as we experience on Earth,” Jennifer Whitten, postdoctoral fellow at the Museum’s Center for Earth and Planetary Studies, said.
Here in North America, we’re in the midst of a bitter winter. South of Mars’ equator, where the Curiosity rover is recording weather data, is experiencing what Whitten calls a “tropical wintertime.”
That equatorial region is at the start of its winter season right now, so temperature comparisons are a little skewed—our coldest temperatures versus some of Mars’ warmest. Recently on Mars (on what would have been January 1, 2018 on Earth), the ground temperature was a high of -6 Celsius, or 21.2 Fahrenheit. That’s on par, or above, the temperatures on Earth in the northeastern United States. The ground temperature on Mars later dipped down to a low of -82 degrees Celsius—that’s -115.6 Fahrenheit, so by that measurement, Mars has us beat for frigid temperatures.
Extreme weather, like some are experiencing on Earth right now, also happens on Mars, but in a different way.
“There are no oceans or other geographic features like we have on Earth that regulate climate,” Whitten said. “The oceans and movement of water regulate temperate a bit. On Mars, you have a mostly dry landscape sprinkled with craters, volcanoes and valleys. The topography affects the weather.”
On Mars, that means wind and dust.
Dust storms are common on the Red Planet. These can be small tornadoes, called dust devils, or global storms that form when the Sun heats dust on the surface, causing it to rise up into the planet’s thin atmosphere. NASA’s first images from Mars, taken by the Mariner 9 spacecraft in 1971, were captured in the midst of one of these dust storms. Because of Mars’ atmosphere, though, the wind doesn’t blow too fast—at its peak, only about half of the wind speed of a hurricane on Earth.
Scientists also believe that the planet has experienced large climatic changes, including global snowstorms, when the planet’s axis wobbled and pointed its polar cap toward the sun. This caused trapped C02 from its coldest regions to melt or sublime. Geophysical evidence, gathered from decades of studying the planet and its climate, points to this, but we’ve never witnessed this type of storm. That’s because it happens infrequently—once every 10 to 20 million years or so.
Though on Earth we can count on our next bout with winter weather to happen a little sooner than it will on Mars, Shindell noted that these extreme temperatures are a small taste of what astronauts would encounter when exploring the Red Planet. So, if you break out your winter parka this weekend, we give you permission to pretend it’s a spacesuit.