Throughout a long time the scientists actively are engaged in search of proofs that on other planets there is life. The sphere of scientific search is not limited to borders of the Solar system. The Universe is boundless, in it there can quite be independent centers of life. However survey results meanwhile do not give the grounds for optimism.
1. The fact of existence of life on Earth does not need confirmation. More difficult the situation with other planets which are a part of the Solar system is. It is considered to be that around the Sun on independent orbits eight such large celestial bodies rotate: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranium and Neptune. Pluto in 2006 lost the status, having passed into the category of dwarf planets. Still there are no objective confirmations that on one of these planets, except for, of course, Earth, there is life.
2. That on the planet even the simplest life forms could develop, existence of the atmosphere and water is required. Life is very sensitive to sharp differences of temperature and pressure. One of living conditions of organisms – the gravitation indicators close to terrestrial. The celestial body also has to receive sufficient, but not excess amount of energy. Researchers who study planets of the Solar system seek to find on them at least some of the characteristics described above.
3. A long time Mars was the first candidate for the place, where living beings can live. It is established that there is an atmosphere though it is very strongly rarefied and is not suitable for breath of the person. Acceleration of gravity on Mars not too strongly differs from terrestrial. Average temperature on the planet – about 60 wasps.
4. The latest data allow to claim that on Mars there are signs of water. It is possible that in similar conditions some vital forms can survive, but it can be established only after visit of the Red planet by the expedition equipped with the modern equipment for carrying out the analysis of the environment.
5. In search of life traces the scientists look narrowly also at Venus. It also belongs to the class of the planets similar to Earth. Venus on many properties is almost completely opposite to Mars. There is water. There is on this planet also an atmosphere, but it extremely dense and saturated that creates "greenhouse" effect. Venus is closer to the Sun, than Earth, and therefore the average temperature of the environment reaches 400 OS there. All these conditions exclude existence on Venus of life which could be similar terrestrial.
6. Other planets of the Solar system differ in even more extreme conditions that reduces existence probability on them the developed life forms almost to zero. However scientists do not lose hope in the future to find the simplest forms which in principle can give rise to development of biological objects on the remote celestial bodies.
7. It is possible that life including reasonable, exists far outside the Solar system and the Galaxy which includes the Sun. The planets similar to Earth, at the beginning of this century were found near some remote stars. But, unfortunately, the modern level of science and technology does not allow to confirm or disprove any concrete hypothesis of researchers. The question of existence of life on other planets remains open.