Jupiter rises an hour after Saturn and is about 30° high in the southeast June 1 at 4:30 A.M. local time, just as the first signs of twilight paint the sky. It shines at magnitude –2.4 among the dimmer stars of Aquarius the Water-bearer. Jupiter’s eastward progression slows until it reaches a stationary point June 21. The planet has brightened to magnitude –2.6 and stands 8.5° northeast of a waning gibbous Moon the morning of June 28.
Viewing improves during the month and by June 30, when it rises shortly before midnight, Jupiter stands nearly 40° high at 4:30 A.M. local time. This is the highest Jupiter has been in Northern Hemisphere skies for four years. The higher elevation improves its brightness and clarity as light from the planet passes through less of Earth’s atmosphere.
Jupiter’s disk spans 41" as June begins and grows to a fine 45" wide by month’s end. The gas giant is still two months from opposition but offers an outstanding view through telescopes. The main equatorial belts straddle the middle of the planet, while subtle dusky features transit quickly from east to west as Jupiter’s fast rotation period carries them across the visible disk. That rotation period varies with latitude but ranges from five to 10 minutes less than 10 hours, so the motion of features is visible with just a few minutes of careful observation.
Jupiter’s four Galilean moons, Io, Europa, Ganymede and Callisto, are also visible most nights. Their changing positions are fun to track.
Neptune is located in northeastern Aquarius and reaches a stationary point June 26. It rises just after 2 A.M. local time June 1, and two hours earlier by June 30. On the 1st, Neptune stands 5.6° east of Phi (ϕ) Aquarii and due south of the Circlet in Pisces. The ice giant’s magnitude of 7.8 places it within range of binoculars an hour or two before dawn. Its identity is easy to verify, especially with a good star map. Neptune remains within 7' of a slightly brighter (magnitude 7.2) field star all month, appearing like a double star. Although the planet moves slowly from night to night, its motion relative to this star is easy to notice.
Uranus emerges in the predawn sky and is best found using binoculars in late June, when the planet stands about 20° high as twilight breaks. It lies in Aries, nearly 12° southeast of Hamal, the Ram’s brightest star. Uranus picks up a double during the last few days of the month as it comes close to Omicron (ο) Arietis, a field star of similar brightness to the magnitude 5.9 planet. On June 30, the bluish planet stands 11' due north of the star.
Mercury reaches inferior conjunction with the Sun on June 10 and moves west of the Sun in late June. It’s too faint to spot in bright twilight until the last week of the month. On June 30, the planet shines at magnitude 1 and is just over 8° east of Aldebaran in Taurus. Look east at 4:30 A.M. local time to find Aldebaran 5° high; over the next half hour, see if you can spot Mercury as it rises while the sky brightens. Observers in the Southern Hemisphere and the tropics have a better view.
Earth’s summer solstice occurs June 20 at 11:32 P.M. EDT.
An annular solar eclipse takes place June 10. Annular eclipses occur when the Moon is farther than average from Earth during a total solar eclipse, making our satellite too small to cover the entire solar disk. This leaves a ring of solar photosphere visible along the center line of the eclipse. The eclipse track runs across the extreme northern regions of Canada, Greenland, and the Arctic Ocean, as well as far northeastern Russia.
In Canada, the annular eclipse will be visible starting about 100 miles northeast of Thunder Bay, Ontario. A partial eclipse is already underway at sunrise (about 5:50 A.M. local time). The low altitude of the Sun when annularity begins just after sunrise means a very clear sky is required to see it. The path continues across barren land until it reaches the Hudson Bay at Polar Bear Provincial Park. Eclipse chasers from the cities of Toronto, Montreal, Ottawa, and Quebec can take Route 11 through North Bay, Ontario, and cross into the path of the annular eclipse just beyond the small town of Mattice, Ontario.