Mars mysteries: Giant plumes, the jelly doughnut and more

The huge cloud-like plumes recently spotted high above the surface of Mars are just the latest Martian mystery to captivate us.

Scientists can't explain cloud-like plumes above surface of the red planet

A curious plume-like feature was observed on Mars in May 1997 by the Hubble Space Telescope. It is similar to the features detected by amateur astronomers in 2012, although it appeared in a different location. (JPL/NASA/STScI)

Huge cloud-like plumes are just the latest red-planet mystery to captivate our attention.

Scientists still do not know what to make of the plumes, which were spotted almost three years ago.

In an essay this week in the journal Nature, a team of international scientists estimate the plumes rose 250 km above the planet’s surface, covering an area of 1,000 km by 500 km.

But scientists cannot say for sure how the plumes rose or what they are made of.

This anomaly is only one of many from our neighbouring planet that has sparked our earthling curiosity and imagination. Here are five other red-planet mysteries.

The face on Mars

This image, taken by the Viking spacecraft July 31, 1976, shows an apparent face on the surface of Mars. NASA scientists say the image is an optical illusion caused by the angle of the sun. (NASA/Associated Press)

NASA’s Viking 1 spacecraft took photographs of a human-like "face" on the planet’s surface in 1976. Ever since, the face on Mars has been talked about in movies, television, radio, and magazines.

While some believed the face was built by aliens, NASA said it was an optical illusion caused by the angle of the sun.

Satellite images taken several years after it was first photographed found the face was actually a natural land form not resembling a face at all.

Martian canals

Italian astronomer Giovanni Virginio Schiaparelli observed what he believed was a system of channels on Mars in 1877. Many people mistook his labelling of "canali" to mean the waterways had been created by intelligent life. (Giovanni Schiaparelli/Wikimedia Commons)

Astronomer Giovanni Virginio Schiaparelli began mapping and naming areas on Mars in 1877. He saw channels on the planet and labelled them "canali."

This term was misinterpreted to mean canals and because of this, many people widely believed the planet had intelligent life that created these waterways.

While scientists later debunked this belief, satellite images show the red planet may have once had natural channels containing fast-moving water.

The jelly-doughnut rock

A photo from the panoramic camera of the Mars Opportunity rover shows the "jelly-doughnut" rock that baffled NASA scientists. (NASA)

Early last year, the Mars Opportunity rover baffled NASA scientists when it produced an image that looked like a pastry-shaped object on the planet’s surface.

The photos, taken in the same spot 12 days apart, show the object in the second photo but not in the first. NASA scientist Steve Squires told reporters that it looked like a jelly doughnut.

But the jelly doughnut was actually a rock that NASA scientists believe was likely kicked into the spot as the rover moved around.

Mysterious lights

This image from NASA's Mars Curiosity rover includes a bright spot near the upper left corner. Typical explanations for such spots are cosmic rays or sunlight glinting from rocks. (NASA/JPL-Caltech)

UFO conspiracy theorists believed images from NASA’s Curiosity rover showed aliens landing on the red planet.

Mysterious lights appearing in the photos were the proof, according to the conspiracy theorists who expressed their beliefs on social media.

NASA scientists said the so-called lights were in fact stray cosmic rays sometimes seen in space.

Is it a rat or a squirrel?

Is it a rat or a squirrel? The red circle highlights what appears to be a rodent-shaped rock lying between two other rocks. (NASA/JPL-Caltech/MSSS)

Some say it looks like a rat. Others say it looks like a squirrel.

In 2012, images from the Curiosity rover showed an orange rodent-shaped rock. Some believed it was an actual rodent hiding among other rocks.

A close-up of the image shows what looks like eyes, a nose, arms, and a sprawled-out body.

But it's really just another rock.

More Mars photos

Some notable shots captured by the Mars rovers in 2014.