How many planates are there in cosmos?

Answer 1

We can't even guess. Starting eight years ago and up until last year, we had discovered a handful of exo-planets - planets that orbit a star other than the Earth. A new research satellite was launched last year, and we have since discovered 500 or more exo-planets; and good indications of a thousand more.

It used to be that astronomers thought that planetary systems would probably be rare. But we're discovering planets - MANY planets - around nearly every star we study, and in numbers that were undreamed of. In fact, it's possible that we will find that a majority of stars will have planets. If half of the stars have planets, and they average 2 planets per star, then there might be one TRILLION planets in the Milky Way galaxy alone! This number might be way off - but we're not sure whether this is more likely to be much too high, or far too low!

Answer 2

There are currently eight planets in our solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.