Asterisms can be any identified pattern or group of stars, and therefore are a more general concept than the 88 formally defined constellations.
[1][2] For example, the asterism known as the Big Dipper or the Plough comprises the seven brightest stars in the constellation Ursa Major.
[citation needed] Exploration by Europeans to other parts of the globe exposed them to stars previously unknown to them.
Two astronomers particularly known for greatly expanding the number of southern constellations were Johann Bayer (1572–1625) and Nicolas Louis de Lacaille (1713–1762).
[citation needed] In 1928, the International Astronomical Union (IAU) precisely divided the sky into 88 official constellations following geometric boundaries encompassing all of the stars within them.
[citation needed] Some asterisms consist completely of bright first-magnitude stars, which mark out simple geometric shapes.