Theres no pictures of the planet, hell they dont even know what it acutally really looks like. Its just that when theres a large object (metior / large planet) that orbits around a star - the star wobbles due to the gravity, so thats the only way they know that theres a planet, and it wobbles a certain amount that we can tell how far away it is, Theres a length in space away from a star that we call the life reigon, where water is a liquid and there is also earth, so humans could survive on planets in 'the life reigon'
So basicly: They dont know what the planet looks like, they can just tell theres a planet there because the star wobbles a bit whenever theres a planet close to a star. It wobbles a certain amount so we can tell that its far away enough to get heat from the sun and water is still a liquid, called the life reigon.