Why is earth important to the solar system?

Answer 1

In the astrophysical sense alone, Earth could be argued not to be important to the solar system and that it is more the logical converse - the solar system is important to Earth, particularly the presence of a star to provide energy and a favorable distance from the Sun such that most water is in liquid state so that life can flourish here. Also, the giant outer planets act as an important shield to Earth, deflecting or absorbing inbound objects that might pose a risk of impact damage to our fragile ecosystem.

The influence of Earth on remainder of the solar system is rather trivial - it might provide a minor perterbation of orbits of other planets but not significant. Some astronomers have pointed out that the solar wind can catch spores, bacteria, viruses in the upper atmosphere and push it in a kind of spiral shape outwards along the plane of the ecliptic to occasionally land on other planets; however there is no documented evidence that such life has ever "taken root" on another body.