Is there life in our galaxy? In the distant future, when her descendants look back on the first half of the 21st century, what will they remember us for? Maybe when we took the first steps to answer the question, is there life outside our own planet? 

New instruments like NASA's James Webb Space Telescope could bring us closer to that answer. How do we find life in our galaxy? First, we need to identify planets with a potential to host life. We've been working towards this goal for the last 20 years. Now the science of planets around other stars or exoplanets has grown from science fiction to reality. 

Before 1995, we only knew the planets in our own solar system. Now we know of several thousand planets and are likely to discover thousands more. Nearly every star has planets and at least one in 10 has an Earth sized planet, and some have more than one. 

Each of the stars in this image might have many planets, but how would we know? Imagine if we were aliens looking at the sun from far away, how would we know Earth was there? Earth is 1 trillion times fainter than the sun and very close to it. Try looking for a firefly next to a big searchlight and you can understand the problem.