... m an infinitely compact state 13.7 billion years ago. The initial conditions are not known, but less than a second after the beginning, temperatures were trillions of degrees Celsius and the primordial universe was much smaller than an atom. It has b ...

Artwork conceptualising the expanding and accelerating Universe. Since the 1990s, astronomers have known that the Universe is not only expanding, but that the rate of expansion itself is accelerating. This is postulated to occur due to a mysterious d...

... tery world with rivers, lakes and small seas from melting snow. Similar to summer in Iceland. The great Valles Marineris was beginning to form, and the Tharsis volcanoes along with it. The Hesperian Period was more like Iceland in the winter, cold an ...

... tery world with rivers, lakes and small seas from melting snow. Similar to summer in Iceland. The great Valles Marineris was beginning to form, and the Tharsis volcanoes along with it. The Hesperian Period was more like Iceland in the winter, cold an ...