The more astronomers study the universe in search of signs of life like ours, the more they come to realize just how much of an exception Earth really is. Not only is it at just the right distance from the sun — a little closer, like Venus, and the oceans would boil up; a little further, like Mars, and half the planet would be in permanent ice — but there are remarkably few planets overall around the other stars. The first one ever to be found was orbiting around a well-studied star thought capable of supporting life.

On this day, October 6, in 1995, the first planet outside our solar system was found, around the star 51 Pegasi, around 50 light-years away from Earth.

The planet, named 51 Pegasi B, is not likely to contain life, as it is a gas giant half the size of Jupiter and orbits much closer to the star than molten Mercury does to the sun — temperatures on 51 Pegasi B are thought to reach 1,000°C (1800°F), but there is a “habitable zone” around the star, a ring in space inside of which a planet might support life under certain conditions. None have been found yet, but the search continues.