Bootes constellation. North is at top. Its brightest star is Arcturus (Alpha Bootis, lower center), which is the fourth brightest star in the sky. At upper right are some of the stars in The Plough (part of the constellation Ursa Major, the great bear). At center left is the small constellation Corona Borealis, the northern crown. This comprises an arc of stars with the bright star Alphecca, or Gemma (Alpha Coronae Borealis) at its center. These northern constellations are best observed in spring and summer from the northern hemisphere.