Mars is very aptly nicknamed “The Red Planet.” Aside from some dry ice polar caps, the landscape on Mars is cold, dry, and rocky. However, that wasn’t always the case. Four billion years ago Mars was covered in water. It had a much thicker atmosphere that kept the planet warm enough for rivers to flow and for liquid water to stand. On November 18, NASA will be launching the Mars Atmosphere and Volatile EvolutioN (MAVEN) which will try to determine what happened to the atmosphere on Mars. In the meantime scientists have speculated about what Mars may have looked like in its heyday. The crew from the Goddard Conceptual Image Lab has put together a video of what a flyover would look like if Mars were covered in water. Some estimates have claimed there could have been as much as 1640 feet (0.5 km) of water covering the entire planet. Liquid water is a vital ingredient for life and the potential for life on Mars has been hotly debated lately. The high-resolution video depicts the history of Mars over the last 4 billion years. The scene opens on a landscape covered in water with white, billowy clouds overhead. As the clouds begin to roll, it shows the passage of time. The atmosphere thins out, causing the water to evaporate. Gradually, all of the rivers and lakes dry up and the atmosphere is too thin to retain any of the sun’s heat. It ends with the Mars we know today: a barren, ice cold rock. There are a few leading ideas about what may have happened to the atmosphere on Mars which include asteroid impact and the loss of the magnetic field due to solar wind. According to the Mars Global Surveyor, Mars has not had a magnetic field in 3.7 billion years. MAVEN will reach the planet in September 2014 and will hopefully answer many questions about what has happened over the last 4 billion years to change the surface of Mars so drastically.