Which star is the fourth brightest in the night sky?

The fourth brightest star in the night sky is Arcturus. Located in the constellation Boötes, Arcturus is a red giant star and is notable for its brightness due to both its intrinsic luminosity and its proximity to Earth, at about 36.7 light-years away. It shines with a magnitude of approximately -0.05, making it very prominent in the night sky.

In the context of the other stars mentioned, Polaris, while famous as the North Star, ranks much lower in brightness compared to Arcturus, being the 48th brightest. Alpha Centauri is the closest star system to Earth, but its components are not as bright as Arcturus, with the primary star having a magnitude of about -0.27, placing it just outside the top four. Aldebaran, although well-known as the eye of the Taurus constellation, is also less bright, with a magnitude around 0.85, which situates it well beyond Arcturus in terms of visibility.

Thus, due to a combination of its luminosity and proximity, Arcturus rightfully holds its rank as the fourth brightest star in the night sky.