DEFINITIONS / VOCAB Flashcards
What is an asterism?
An asterism is a pattern of stars that is smaller than a constellation. It is often recognized as a recognizable group or shape of stars within a constellation. For example, the Big Dipper is an asterism within the constellation Ursa Major.
What’s a constellation?
A constellation is a group of stars that, when viewed from Earth, appear to form a recognizable pattern or shape. There are 88 official constellations recognized by the International Astronomical Union (IAU).
What’s the name of the boundary around each constellation?
The “celestial boundary” or “official constellation boundary.” These boundaries were defined by the International Astronomical Union (IAU) in the early 20th century as a way to standardize the constellations and help astronomers identify and study them. The boundaries are defined based on lines of right ascension and declination, which are like longitude and latitude lines on Earth.
Constellation boundaries form a jigsaw all over the celestial sphere.
What’s a pointer star?
A pointer star is a star that is used to locate another star or celestial object. The most famous example of a pointer star is in the constellation Ursa Major, where the two stars at the end of the Big Dipper’s bowl are often used to find Polaris, the North Star. These stars are sometimes also called “guide stars” or “direction stars.”
