Mars SnowflakesDid you know that it snows on Mars?  It’s not exactly the same kind of snow that we have here on Earth, but it is frozen precipitation.

Mars snowflakes are much smaller than the ones here on Earth.  In fact, they have about the same diameter as a human red blood cell, according to a new study.

Researchers analyzed observations made by two Mars-orbiting spacecraft to determine the size of snowflakes on Mars, which are made up of carbon dioxide as opposed to water.

“These are very fine particles, not big flakes,” study co-author Kerri Cahoy, of the Massachusetts Institute of Technology in Cambridge, said in a statement. An astronaut standing out in the snow on Mars would like “see it as a fog, because they’re so small,” Cahoy added.

Clouds of snow loom over Mars during the planet’s winter season, covering its poles and reaching approximately halfway to the equator. The researchers studied observations of these clouds made over the last ten years or so by NASA’s Mars Global Surveyor (MGS) and the Mars Reconnaissance Orbiter (MRO).

The scientists found that the sizes of the particles varied from pole to pole, with flakes in the northern hemisphere measuring between 8 to 22 microns and those in the southern hemisphere measuring only 4 to 13 microns.

That makes them comparable to the width of a human red blood cell, the researches said.

“For the first time, using only spacecraft data, we really revealed this phenomenon on Mars,” said lead author Renyu Hu, a grad student at MIT.

The results of the study will be published in an upcoming issue of the Journal of Geophysical Research.