Before the first exploration missions, due to its similar size and proximity to Earth, people imagine Venus to potentially have oceans and life forms. Its thick atmosphere creates a greenhouse effect, making Venus the hottest planet in the solar system with an average surface temperature of 470 degrees Celsius. A Venucian day is shorter than its year. The atmospheric pressure on Venus is 92 times greater than that of Earth. This intense pressure is equivalent to the conditions at a depth of around 1 kilometer beneath Earth's oceans. Venus rotates in the opposite direction from the other planets, possibly due to a massive collision with another celestial object. The planet's color is due to the thick layer of clouds composed mainly of sulfuric acid droplets. Venus has a weak intrinsic magnetic field, despite being considered a non-magnetic planet.