The brightest star in the northern sky, apparent magnitude −0.05, also known as α Boötis. It is a yellow giant star of spectral type K1.5, one of the nearest giants to the Earth at a distance of 11.25 parsecs (2.16 × 10¹⁴ mi or 3.47 × 10¹⁴ km). Unlike the Sun, which is currently converting hydrogen into helium in its core, Arcturus has already exhausted its central hydrogen and has evolved away from the main sequence. It is approximately 25 times larger in diameter than the Sun, and more than 100 times more luminous. Its effective temperature is estimated to be 7700°F (4300 K).