Which star is known as the 4th brightest in the sky?

Arcturus is known as the fourth brightest star in the night sky. It is a red giant star located in the constellation Boötes and is part of a group of stars called the "first magnitude" stars, which are among the most luminous and easily visible. The brightness of a star is measured by its apparent magnitude, and Arcturus has an apparent magnitude of around -0.05.

Sirius, with an apparent magnitude of -1.46, is the brightest star in the night sky, followed by Canopus and Alpha Centauri. Altair and Betelgeuse are also bright stars but are ranked below Arcturus in terms of apparent brightness. Altair has an apparent magnitude of about 0.77, while Betelgeuse varies between 0.3 and 1.2, depending on its pulsations. Thus, Arcturus holds its position as the fourth brightest star due to its substantial size, luminosity, and proximity to Earth.