A star is a massive, luminous sphere of plasma held together by gravity. The nearest star to Earth is the Sun, which is the source of most of the energy on the planet. Some other stars are visible from Earth during the night when they are not obscured by atmospheric phenomena, appearing as a multitude of fixed luminous points because of their immense distance. Historically, the most prominent stars on the celestial sphere were grouped together 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 a star's hydrogen is nearly exhausted, almost all naturally occurring elements heavier than helium are created, either via stellar nucleosynthesis during their lifetimes or by supernova nucleosynthesis when very massive stars explode. Near the end of its life, a star can also contain a proportion of 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 are determined by its evolutionary history, including diameter, rotation, movement and temperature. 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.
Mount Fuji (富士山, Fuji-san?, IPA: [ɸɯꜜdʑisaɴ] ( listen)), located on Honshu Island, is the highest mountain in Japan at 3,776.24 m (12,389 ft). An active stratovolcano that last erupted in 1707–08, Mount Fuji lies about 100 kilometres (60 mi) south-west of Tokyo, and can be seen from there on a clear day. Mount Fuji's exceptionally symmetrical cone, which is snow-capped several months a year, is a well-known symbol of Japan and it is frequently depicted in art and photographs, as well as visited by sightseers and climbers. It is one of Japan's "Three Holy Mountains" (三霊山, Sanreizan?) along with Mount Tate and Mount Haku; it is a Special Place of Scenic Beauty, a Historic Site, and has been submitted for future inscription on the World Heritage List as a Cultural (rather than Natural) Site.