Mars
YouTube: Secureteam10

A strange cloud seemingly looking like a plume of smoke near a massive Martian volcano is now puzzling astronomers and conspiracy theorists alike.

The cloud was initially spotted by European Space Agency's (ESA) Mars Express spacecraft on September 13 over the Arsia Mons volcano.

Even though many astronomers cited a volcanic eruption behind these strange smoke clouds, ESA dismissed this angle and made it clear that no volcano has been active in the Red Planet for the past 50 years. As per the agency, the strange smoke over Mars could be actually a water ice cloud.

"In spite of its location, this atmospheric feature is not linked to volcanic activity but is rather a water ice cloud driven by the influence of the volcano's leeward slope on the air flow – something that scientists call an orographic or lee cloud – and a regular phenomenon in this region," said the European Space Agency in a recent statement.

ESA also added that 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."

Meanwhile, several conspiracy theorists started putting forward various theories explaining this bizarre smoke cloud. Tyler Glockner, a popular UFO researcher who operates the YouTube channel 'Secureteam10' argued that the plume of smoke above the volcano could be the result of a gigantic explosion.

"There was an explosion. I don't know whether it was a volcano or something detonated," said the conspiracy theorist in a recent clip uploaded on his YouTube channel.

Some other conspiracy theorists argued that the smoke cloud over Mars is an artificial structure specially designed to hide the sinister activities on the Martian surface. These theorists believe that alien life might be thriving on Mars, especially below the planet's surface.

Now, the European Space Agency has set up a Flickr page to monitor the changes happening to the strange clouds over the Martian volcano.