The discovery was made on a planet called HD 189733b, which is 63 light-years away from Earth in the constellation Vulpecula. Hubble also confirmed the existence of water molecules in the planet's atmosphere--a discovery made by NASA's Spitzer Space Telescope in 2007.
The planet is called a "hot Jupiter" because it is about the size of the giant planet in our solar system but is closer to its sun than planet Mercury is to ours. It takes the planet just two days to orbit its sun. Its temperature is about 1,700 degrees Fahrenheit, considered to be too hot for life as we know it. But this discovery means that methane and other compounds can probably be identified on other, more Earth-like, planets somewhere in the galaxy.