Astronomers believe this primitive ocean was big enough to cover nearly half of the hemisphere, also quite deep

Mar 6, 2015 08:20 GMT  ·  By

These days, Mars strikes us as a dry and barren place. However, astronomers say that this was not always the case. On the contrary, evidence indicates that there was a time when the Red Planet had liquid water covering a great deal of its surface.

In fact, a study authored by an international team of researchers and published in yesterday's issue of the journal Science says that, about 4 billion years ago, a mammoth ocean obscured most of Mars' northern hemisphere from sight.

More precisely, astronomers say that this primitive body of liquid water was most likely big enough to cover about half of the Red Planet's northern hemisphere and that, in some regions, it reached depths of well over 1 mile (roughly 1.6 kilometers).

If you have 30 seconds to spare and happen to be in the mood to get a better idea of what scientists believe this cosmic neighbor of ours looked like 4 billion years ago, check out the video below showing an artist's impression of young Mars.

A better understanding of the Red Planet's history

In the report detailing their work, the scientists behind this study explain that they documented the existence of a primitive ocean on Mars with the help of ESO's Very Large Telescope and other instruments at the W. M. Keck Observatory and the NASA Infrared Telescope Facility.

Specifically, the astronomers used the Very Large Telescope and the other research tools that they had access to to produce maps detailing the makeup of the Red Planet's atmosphere and its evolution over the course of a 6-year period.

“Our study provides a solid estimate of how much water Mars once had, by determining how much water was lost to space. With this work, we can better understand the history of water on Mars,” study lead author Geronimo Villanueva said in a statement.

Based on the current water content of Mars' atmosphere, the astronomers concluded that, some 4 billion years ago, the planet likely held enough water to have its entire surface covered in a layer measuring about 140 meters (460 feet) in depth.

However, it is improbable that this is what the Red Planet looked like. Instead, scientist Geronimo Villianueva and his colleagues believe that all this water formed a single and surprisingly deep ocean covering almost half of Mars' northern hemisphere.

Mars' primitive ocean was quite a sight

As mentioned, the ocean that covered part of the Red Planet's northern hemisphere 4 billion years ago could reach depths of over 1 mile (1.6 kilometers). It likely sat in a region now known as the Northern Plains and had a volume of about 20 million cubic kilometers (nearly 5 million cubic miles).

Just to put things into perspective, astronomer Geronimo Villanueva and fellow researchers explain that this implies that the ocean covered roughly 19% of the planet’s surface. By comparison, our Atlantic Ocean covers 17% of the Earth’s surface.

If is true that such a large body of liquid water once rested atop Mars' surface in the planet's northern hemisphere, this means that, in its early years, our cosmic neighbor might have been habitable. Whether or not life emerged in this corner of our Solar System remains a mystery.

Mind you, Mars still holds water on its surface in this day and age. The thing is that it is not flowing freely or anything of the sorts, but is instead frozen in the polar caps towering over its northern and its southern hemispheres, scientists explain.