They have very minor gravitational effects. Not noticeable but can be calculated.
The other planets do have gravity.
Essentially none at all. The gravitational force of the Sun is so much more influential than the gravity of any other planet that we can ignore the influence of other planets.
No. Earth's magnetic field only affects earth, not other planets.
Since no one from Earth has visited another planet, and we have no indication that there is anyone on the other planets, Earth does not help other planets in any way. Why do you think there is something Earth does to help them- whoever them is.
yes, the earth and other planets revolve around the sun
Earth and the other planets are mostly made of rock.
Earth and the other planets are mostly made of rock.
The other planets actually do have seasons.
Studying the earth helps scientists to understand other planets since the earth is part of the solar system. Scientists use the features of the earth to compare them with what other planets hold.
Astronomers have found Earth-sized planets in other solar systems.
No, other planets are rotating at other speeds.