A star is a luminous sphere of plasma held together by its own gravity. The nearest star to Earth is the Sun. Other stars are visible to the naked eye from Earth during the night, appearing as a multitude of fixed luminous points in the sky due to their immense distance from Earth. Historically, the most prominent stars were grouped into constellations and asterisms, and the brightest stars gained proper names. Extensive catalogues of stars have been assembled by astronomers, which provide standardized star designations.
For at least a portion of its life, a star shines due to thermonuclear fusion of hydrogen into helium in its core, releasing energy that traverses the star's interior and then radiates into outer space. Once the hydrogen in the core of a star is nearly exhausted, almost all naturally occurring elements heavier than helium are created by stellar nucleosynthesis during the star's lifetime and, for some stars, by supernova nucleosynthesis when it explodes. Near the end of its life, a star can also contain degenerate matter. Astronomers can determine the mass, age, metallicity (chemical composition), and many other properties of a star by observing its motion through space, luminosity, and spectrum respectively. The total mass of a star is the principal determinant of its evolution and eventual fate. Other characteristics of a star, including diameter and temperature, change over its life, while the star's environment affects its rotation and movement. A plot of the temperature of many stars against their luminosities, known as a Hertzsprung–Russell diagram (H–R diagram), allows the age and evolutionary state of a star to be determined.
Stars is the fourth album by British-based pop/soul/jazz band Simply Red, released in September 1991. Five singles were released from the album, including the UK top ten hits "Stars" and "For Your Babies". The album was a worldwide success, particularly in the band's home country where it has been certified twelve times platinum and was the best-selling album of the year in the UK for both 1991 and 1992, the first album to be the best-seller in two consecutive years since Simon & Garfunkel's Bridge over Troubled Water in 1970–71. As of February 2014 it is the 14th best-selling album of all time in the UK.
Stars was also the last album to feature member Tim Kellett, who started his own band Olive after touring. It is the only Simply Red album to feature Fritz McIntyre singing lead vocals, on the tracks "Something Got Me Started" and "Wonderland".
It was on the shortlist of nominees for the 1992 Mercury Prize. In 2000 Q placed Stars at number 80 in its list of "The 100 Greatest British Albums Ever".
Although the compound of three octahedra used for the central cage in Stars had been studied before in mathematics, it was most likely invented independently for this image by Escher without reference to those studies. Escher used similar compound polyhedral forms in several other works, including Crystal (1947), Study for Stars (1948), Double Planetoid (1949), and Waterfall (1961).
The design for Stars was likely influenced by Escher's own interest in both geometry and astronomy, by a long history of using geometric forms to model the heavens, and by a drawing style used by Leonardo da Vinci. Commentators have interpreted the cage's compound shape as a reference to double and triple stars in astronomy, or to twinned crystals in crystallography. The image contrasts the celestial order of its polyhedral shapes with the more chaotic forms of biology.