Vega (α Lyr / α Lyrae / Alpha Lyrae) is the brightest star in the constellation Lyra, the fifth brightest star in the night sky and the second brightest star in the northern celestial hemisphere, after Arcturus. It is a relatively nearby star at only 25.3 light-years (7.8 pc) from Earth, and, together with Arcturus and Sirius, one of the most luminous stars in the Sun's neighborhood. In 1983, based on observations by the Infrared Astronomy Satellite (IRAS), Vega became one of the first stars to be discovered with a large luminous infrared-radiating halo that suggests a circumstellar cloud of warm dust. Since Vega seems to be rotating with its pole directed toward Earth, the dust cloud probably represents a face-on disk that may not be unlike the disk surrounding the Sun and that contains the planets. (For further details see Vega.)