
A weird cloud forms on Mars each year and now we know why
Unusual clouds form over the Martian volcano Arsia Mons each year ESA/DLR/FU Berlin/J. Cowart CC BY-SA 3.0 IGO A thin cloud that appears on Mars each year has baffled astronomers ever since it was first spotted, but it may be the result of a moisture-rich atmosphere that was thought impossible. Each winter, an 1800-kilometre-long cloud…