Ultraviolet (UV)

• Good Sources of UV: Ultraviolet radiation comes from hotter objects, including bright young stars, white dwarfs, and binary stars, which are two stars orbiting around one another. Ultraviolet astronomy has been used to show that practically all stars, including even some white dwarfs (stars at the end of their lives), lose matter in the form of stellar winds.
• Ultraviolet light has a difficult time getting through the Earth's atmosphere, so much of ultraviolet astronomy is done from satellites.

Extreme Ultraviolet (EUV)

• Good Sources of EUV: EUV tends to come from objects that are really hot. For instance, white dwarf stars, which are typically ten of thousands of degrees hot, or the outer envelope of stars, typically hundreds of thousands of degrees hot, produce EUV light. White dwarfs are stars near the end of their lives. Once the nuclear energy production has stopped, gravity can squeeze a star the size of our Sun down to the size of the Earth. The "burnt-out" Earth-sized star then cools for millions of years like a brick out of an oven.
• Like most ultraviolet light, extreme ultraviolet light does not go through the Earth's atmosphere, so much of extreme ultraviolet astronomy is done from satellites. One such satellite is our own Extreme Ultraviolet Explorer satellite.

• Extreme Ultraviolet Explorer Satellite