In geometry, a lune is either of two figures, both shaped roughly like a crescent Moon. The word "lune" derives from luna, the Latin word for Moon.

In plane geometry, a lune is the concave-convex area bounded by two circular arcs, while a convex-convex area is termed a lens.

Formally, a lune is the relative complement of one disk in another (where they intersect but neither is a subset of the other). Alternatively, if A and B are disks, then Failed to parse (Missing texvc executable; please see math/README to configure.): L = A - A \cap B

In spherical geometry, a lune is an area on a sphere bounded by two half great circles, which is also called a digon or a diangle or (in German) a Zweieck. Great circles are the largest possible circles on a sphere; each great circle divides the surface of the sphere into two equal halves. Two great circles always intersect at two polar opposite points. Common examples of great circles are lines of longitude (meridians), which meet at the North and South Poles. Thus, the area between two meridians of longitude is a lune. The area of a spherical lune is 2θ R², where R is the radius of the sphere and θ is the dihedral angle between the two half great circles. When this angle equals 2π — i.e., when the second half great circle has moved a full circle, and the lune in between covers the sphere — the area formula for the spherical lune gives 4πR², the surface area of the sphere.

Roky Erickson (born Roger Kynard Erickson on July 15, 1947) is an American singer, songwriter, harmonica player and guitarist from Texas. He was a founding member of the 13th Floor Elevators and a pioneer of the psychedelic rock genre.

Erickson was interested in music from his youth: he played piano from age 5 and took up guitar at 10. He attended school in Austin and dropped out of Travis High School in 1966, one month before graduating, rather than cut his hair to conform to the school dress code. His first notable group was The Spades, who scored a regional hit with Erickson's song "We Sell Soul"; this song is included on the compilation album Highs in the Mid-Sixties, Volume 17 (although the songwriter is identified as Emil Schwartze on the track listing on this album). Also the song "You're Gonna Miss Me", later a hit for 13th Floor Elevators, was featured on the compilation album The Best of Pebbles Volume 1.

Erickson co-founded the 13th Floor Elevators in late 1965. He and bandmate Tommy Hall were the main songwriters. Early in her career, singer Janis Joplin considered joining the Elevators, but Family Dog's Chet Helms persuaded her to go to San Francisco, California instead, where she found major fame.

Timothy Charles Buckley III (February 14, 1947 – June 29, 1975) was an American vocalist, and musician. His music and style changed considerably through the years; his first album (1966) was mostly folk oriented, but over time his music incorporated jazz, psychedelia, funk, soul, avant-garde and an evolving "voice as instrument," sound. He died aged 28, leaving his son Jeff Buckley from his marriage to Mary Guibert.

Tim Buckley was born in Washington DC on St. Valentine's Day, to Elaine Buckley (née Scalia), an Italian American, and Tim Charles Buckley Jr, who was the son of Irish immigrants from Cork. He spent his early childhood in Amsterdam, New York, an industrial city approximately 40 miles northwest of Albany; here at five years old he made his first acquaintance with music, his mother's progressive jazz recordings (she was a fan of Miles Davis).

Tim's musical life began in earnest after his family moved to Bell Gardens in southern California in 1956. His grandmother had introduced him to Bessie Smith and Billie Holiday, his mother to Frank Sinatra, Miles Davis and Judy Garland and his father to the country music of Hank Williams and Johnny Cash. When he attended Bell Gardens' public schools he was ready to catch the folk bug going around. At the age of 13 he taught himself the banjo, and with his new friend, Dan Gordon, and several others formed a folk group inspired by the Kingston Trio that played local high school events.