Beyond the outer edge of the Solar System, mysterious, unknown worlds await by the thousands. Astronomers can now finally find them and explore them - but will we find another Earth?
Scientists have discovered seven Earth-sized planets packed around a dim star.
If there's life on one of the Earth's seven sisters, chances are it has spread to all of them.
We don't need to look for Earth-like planets exclusively around Sun-like stars. Tiny, dim TRAPPIST-1 has only 11 percent the diameter of the Sun and is much redder.