Diagram caption: The constellation Boötes with its bright stars and surrounding constellations. Boötes is surrounded by (going clockwise from the top): Draco, Ursa Major, Canes Venatici, Coma Berenices, Virgo, Serpens Caput, Corona Borealis and Hercules. It is notable for its brightest star Arcturus which is the fourth brightest star in the night sky.

Boötes is a northern constellation and the whole constellation is visible to the entire northern hemisphere at some point in the year. Parts of the constellation are visible from all but the most antarctic parts of the southern hemisphere but the whole constellation is only visible from equatorial and some temperate parts of that hemisphere. Boötes is most visible in the evenings in the northern hemisphere summer and southern hemisphere winter.

The y-axis of this diagram is in degrees of declination with north as up and the x-axis is in hours of right ascension with east to the left. The sizes of the stars marked here relate to the star's apparent magnitude, a measure of its apparent brightness. The larger dots represent brighter stars. The Greek letters mark the brightest stars in the constellation. These are ranked by brightness with the brightest star being labeled alpha, the second brightest beta, etc., although this ordering is not always followed exactly. The dotted boundary lines mark the IAU's boundaries of the constellations and the solid green lines mark one of the common forms used to represent the figures of the constellations. Neither the constellation boundaries, nor the lines joining the stars appear on the sky.

Diagram credit: Adapted by the IAU Office of Astronomy for Education from the original by the IAU and Sky & Telescope. Credit Link

Related glossary terms: Apparent Magnitude , Celestial Coordinates , Constellation , Declination , Right Ascension (RA)
Categories: Naked Eye Astronomy

Diagram license: Creative Commons Attribution 4.0 International (CC BY 4.0) Creative Commons Attribution 4.0 International (CC BY 4.0) icons