Bootes constellation. North is at top. Its brightest star is Arcturus (Alpha Bootis, right center), which is the fourth brightest star in the sky. At bottom 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.