There’s a Weird Cloud Hanging Around a Dormant Volcano on Mars – Brinkwire

Weather on other planets is strange. Jupiter’s been dealing with a huge storm on its surface for over a century (the infamous ‘Great Red Spot,’ which is about the twice the width of Earth), while Venus has rainstorms made of sulfuric acid. So what about Mars? You might have imagined the Red Planet as a barren wasteland laid bare to the vacuum of space, but that’s not true—it has its own atmosphere and weather, too. In fact, the Mars Express orbiter (operated by the European Space Agency) has recently spotted a long cloud hovering above a Martian volcano.

It’s currently believed that the cloud is made of water ice, and is part of a seasonal pattern of clouds that appear around this time every year. According to a press release: “The cloud’s appearance varies throughout the martian day, growing in length during local morning downwind of the volcano, almost parallel to the equator, and reaching such an impressive size that could make it visible even to telescopes on Earth.” The volcano in question is Arsia Mons, which has lain dormant for 50 million years. Though the cloud is hanging over the summit, it’s definitely not a product of volcanic activity.

Scientists think that the recent, planet-wide dust storm (which forced the shutdown of the NASA rover Opportunity) may have influenced the formation of this cloud, whose properties seem sensitive to the daily conditions of the planet. When photographed by the Mars Express spacecraft, its total length was estimated to be 1500 kilometers. For amateur astro-meteorologists, it’s classified as an ‘orographic’ cloud, which is formed when air is forced upwards by the topography of the planet. In this case, it seems Arsia Mons slopes were the catalyst for the cloud’s formation.

You can read the full press release here.