Along with ourselves, there are seven planets in this solar system: Neptune, Uranus, Saturn, Jupiter, Mars, Venus and Mercury.
As well, there are dwarf planets – like Pluto – asteroids, comets and moons.
We have a rough idea of what these worlds are composed of and are quite certain that none of them can sustain us. Exoplanets are the planets outside our solar system, all of which invisible by telescope and instead detected by the disruption in light from distant stars. Kepler 22b, 600 light years away, is an exciting find because it is similar to earth in size and orbiting distance from its sun.
It is estimated that there are some 100 billion planets in our galaxy alone and a septillion – a thousand billion billion – planets in the universe. As Carl Sagan says, that’s more than all of grains of sand in all of the beaches on Earth. There is little doubt that many of the planets out there have life on them; the question is in their level of intelligence and what kind of shenanigans might occur when we finally meet.