one for now (at least publicly disclosed ;) )
We don't know about any other other place, besides Earth, that harbors life. But many scientists think that there is life on other planets.
Yes, only on the Earth. We don't know if the other planets have life
As far as we know, Earth is the only planet that supports life, but there have been many studies that show that some other planets have either supported life previously or could be capable of supporting life.
No. One planet that we know of, Earth, has life on it but planets themselves are not alive.
We can never know how many planets there are in the entire universe.
2
There is life on other planets. Imagine, there are 1000 planets in the Universe for every grain of sand on the earth. That's how many planets there are, so scientifically, the chance that there must be life on other planets as well is much greater than the chance that there is no life.
The Gaseous Planets The Planets That Are So Far Away That We Don't Even Know If Life Could Exist There (TPTASFATWDEKILCET) :) ;)
Many astronomers, historians, regular people, and scientisis know about the planets in our Solar system.
7
Not yet, but, as we have discovered water on various planets and moon, the possibility of life - as we know it - does exist.
There are probably a billion stars in our galaxy, and probably a billion galaxies in the universe. We already know what there are planets orbiting many other stars; if there are planets around only 1% of the stars, that's still 100 billion planets. If only 1% of those planets are habitable, that's a billion habitable planets. If only 1% of those planets HAVE life, that's 10 million planets with life. If only 1% of the planets that have life have highly-developed life forms, then there are 100,000 planets with highly developed life forms. If only 1% of those planets have intelligent life, that's still 1,000 planets in the universe that have intelligent life; "aliens". We have NO IDEA if there are any other planets that have life, or intelligent life in the universe, or if those aliens - if any exist - might be willing or able to communicate with us. But I would like to think so.