People   327Music   98China TempleJapanese Girl KimonoSylwia Bartyzel Best Mountain Sky NatureNight Sky Milkyway Tree Wood NatureKungfu Panda Dreamworks Art Kick Cute AnimeWolverine Last Hero Art FilmHarry Styles Geminis MusicLake Mountain Reflection Nature BlueSea and RocksDark Sunset Snow Mountain NaturePalm trees SunsetBlackhole Space Red Star Nature ArtModern Warfare 2This artist’s impression shows how Mars may have looked about four billion years ago. The young planet Mars would have had enough water to cover its entire surface in a liquid layer about 140 metres deep, but it is more likely that the liquid would have pooled to form an ocean occupying almost half of Mars’s northern hemisphere, and in some regions reaching depths greater than 1.6 kilometres.Heritage Stripe BlueSky Sunshine Morning Red Blue NatureSpace Interstellar Sky Cloud NatureGalaxy Nexus 7 Abstract Blue Digital PatternMusic   112