Asteroid 3 Juno is visible all night in Serpens Cauda, not far from globular cluster M5.
Asteroid 3 Juno, imaged here by the Atacama Large Millimeter/submillimeter Array, is the third asteroid ever discovered. It now lies at opposition, roughly opposite the Sun in Earth’s sky. Credit: ALMA (NRAO/ESO/NAOJ)
The main-belt asteroid 3 Juno reached opposition yesterday afternoon, meaning it now lies directly opposite the Sun in our sky, rising at sunset and setting at sunrise.Â
Two hours after sunset tonight, Juno is 30° high in the southeast. Glowing at magnitude 10, it’s within reach of binoculars or a small telescope. You can find Juno some 2.3° northwest of magnitude 3.5 Mu (μ) Serpentis, which lies at the far southern border of Serpens Caput near northeastern Libra. The third asteroid ever discovered, Juno is about 155 miles (250 km) across, making it the third-largest body in the main belt.Â
While you’ve got your optics out, slide your gaze a little over 7° northwest of Juno, or roughly 8.5° west-southwest of magnitude 3.7 Epsilon (ε) Ser. There you’ll land on globular cluster M5, which shines at magnitude 5.6 and covers roughly 23’ on the sky. This bright, dense globular has a tightly packed center but its outer regions resolve into several tens of stars under magnification. Astronomers believe it is one of the Milky Way’s oldest globular clusters, with an age of some 13 billion years.
Sunrise: 5:45 A.M.
Sunset: 8:09 P.M.
Moonrise: 11:32 P.M.
Moonset: 7:19 A.M.
Moon Phase: Waning gibbous (92%)
*Times for sunrise, sunset, moonrise, and moonset are given in local time from 40° N 90° W. The Moon’s illumination is given at 12 P.M. local time from the same location.
For a look ahead at more upcoming sky events, check out our full Sky This Week column.Â
