The answer to this question is not known.
No
Because it is simply.. The only planet to live on.
Mercury.
What do mean
All of them.
Venus is Earth's twin.
As far as we know, the only planet that human beings have walked on is the planet Earth; we have also walked on the moon, but that is a satellite, not a planet.
No one knows for sure if life exists outside of the planet Earth. There are some human beings outside of the planet Earth on the International Space Station which is in orbit about 250 miles above the planet.
No. They were seeded here in the 1970's by beings from another planet.
bwisit
Man has made many choices including choices that damage the planet like the introduction of nuclear power. Man has made choices to create wars and choices to build cities.