Jupiter and Saturn reach opposition less than a week apart this month as they make their closest approach to Earth this year. Venus adorns the pre-dawn sky while Mars brightens and moves north along the ecliptic. Northern-hemisphere observers get to enjoy warmer (if shorter) nights when the Milky Way arcs from nearly overhead in the constellation Cygnus down to Sagittarius low over the southern horizon. Southern-hemisphere stargazers enjoy longer winter nights where the thickest part of the Milky Way in Sagittarius lies nearly overhead (along with Jupiter and Saturn). And one of the best meteor showers of the year for southern stargazers, the Delta Aquariids, closes out the month (northern observers can spot a few of these meteors too). Here’s what to see in the night sky this month…
4 July. Earth reaches aphelion, its further point in its orbit around the Sun. Today, the centers of these two celestial bodies are 152,095,295 km apart.
5 July. Full Moon, 04:44 UT
5 July. Jupiter and Saturn join the Full Moon to form a triangle in eastern Sagittarius and western Capricornus.
11-12 July. A waning gibbous Moon lies about three finger-widths from Mars well after midnight. Watch Mars during the month as it brightens significantly from magnitude -0.5 to magnitude -1.0 and grows in apparent size from 11.4” to 14.5”. The planet lies in the constellation Pisces not far from the celestial equator. It rises about 12:30 a.m. at the beginning of July and shortly after 11 p.m. local time by the end of the month. The planet will continue to grow and brighten over the next few months on its way to opposition in October.
12 July. Dazzling Venus takes its place as the ‘Morning Star’ for the rest of 2020. In early July it reaches peak brightness at magnitude -4.7, bright enough to remain visible into the morning twilight, and rises about two hours before the Sun. Look today before dawn to see the planet tangled in the stars of the Hyades star cluster in the constellation Taurus with the Pleiades just above. Venus also passes about one degree north of the bright star Aldebaran. It’s a perfect celestial scene to enjoy in binoculars. In a telescope, watch Venus over the next couple of months change from a large and slender crescent to a slightly smaller and fainter half-lit disk.
12 July. Last-Quarter Moon, 23:29 UT
14 July. Jupiter reaches opposition, rising in the east-southeast as the sun sets in the west-northwest. The planet shines at magnitude -2.8 tonight, brighter than anything else in the night sky except for the Moon and Venus. Jupiter lies at a declination of -22o this year which means northern-hemisphere observers see it through the thick air over the southern horizon. But on nights of steady seeing, and with a bit of patience, it will be possible to glimpse fine detail in the belts and zones of this gas giant with a small telescope. Southern-hemisphere observers get a glorious view of Jupiter nearly overhead near midnight. Our Jupiter Observing Guide will help you get the best view of the planet this year.
17 July. Again, before dawn, look eastward to see brilliant Venus, Aldebaran, and a slender crescent Moon. A beautiful sight in binoculars!
20 July. New Moon, 17:33 UT
20 July. The beautiful planet Saturn lies just 7o east of Jupiter and reaches opposition tonight at its closest approach to Earth this year. Like Jupiter, the planet lies far south along the ecliptic so northerners need steady air to get good views of its magnificent ring system. But it’s worth the effort: Saturn is one of the most beautiful objects to observe in a telescope. Our Saturn Observing Guide will help you get a good view of this lovely celestial object and understand what to look for.
One thing to watch for: in the few days around opposition, Saturn’s rings can appear to brighten considerably. This phenomenon is known as the Seeliger effect in which, from our vantage point, the rings catch the Sun’s full illumination while the shadow cast by the planet on the tiny ring particles briefly disappears.
22 July. Just two days into its new cycle, the thin waxing crescent Moon lies low over the western horizon about three degrees from the first-magnitude star Regulus in the constellation Leo.
27 July. First Quarter Moon, 12:33 UT
27-30 July. The Delta Aquariid meteor shower peaks. This annual event favors observers in the southern hemisphere and southerly latitudes in the northern hemisphere, though all observers can see some of these slow-moving meteors. The Delta Aquariids appear to radiate from a point near the star Skat (delta Aquarii) in the constellation Aquarius. The shower peaks around July 27-30, but unlike most meteor showers, the Delta Aquarids lack a sharp maximum so meteors are visible from mid-July through early August. The maximum hourly rate can reach 15-20 meteors in a dark sky.
31 July. The waxing gibbous Moon and the planets Jupiter and Saturn lie in a long arc east of the ‘Teapot’ asterism in the constellation Sagittarius.