Scientists have only searched through a tiny fraction of our galaxy, and with the fast advances in technology, we can expect many more interesting discoveries in the future. But for now, check out the handy infographic below, courtesy of Space.com, displaying all known types of alien worlds.
A dying star. Chi Cygni, shown in this artist's conception, is a red giant star nearing the end of its life. As it runs out of fuel, it pulses in and out, beating like a giant heart and ejecting shells of material. Observations by the Infrared Optical Telescope Array found that, at minimum radius, Chi Cygni shows marked inhomogeneities due to roiling "hotspots" on its surface. (Credit: ESO/L. Calçada)