June begins a series of excellent months of stargazing in 2020. Through June and into July, the planets Jupiter, Saturn, and Mars grow in size and brightness and reveal plenty of fascinating detail in a small telescope. Venus and Mercury also make appearances, with Venus moving from the evening sky to the morning sky. And of course, the best part of the Milky Way returns with its rich collection of hundreds of star clusters, star-forming regions, dark nebulae, and star clouds. Here’s what to see in the night sky this month…
3 June. Venus reaches inferior conjunction with the Sun and passes only 15’ to the north of the solar disk, just missing a transit. The last transits of Venus occurred in 2004 and 2012, and the next pair arrives on December 10, 2117 and December 8, 2125. After today Venus leaves the evening sky and emerges, bright and beautiful as the ‘Morning Star’ for the next several months.
4 June. Mercury reaches greatest eastern elongation about 24o from the Sun in the evening sky. Northern hemisphere observers see the planet just above the northwestern horizon after sunset, below the stars Castor and Pollux in Gemini. Binoculars are a necessity as the planet, although a relatively bright magnitude +0.6 today, is mired in the long twilight of late spring. Southern hemisphere observers see the planet about four finger-widths above the horizon after sunset between the bright star Betelgeuse in Orion and Castor and Pollux.
4 June. Look for a nearly full Moon about 7o north of the bright star Antares in the constellation Scorpius.
5 June. Full Moon, 19:12 UT
6 June. Mars reaches quadrature at an apparent position 90o west of the Sun. The planet has been speeding eastward from Jupiter and Saturn for the past weeks, but it’s getting closer fast and increases in brightness from magnitude 0.0 to -0.5 as June progresses. It’s disk spans about 11” by month’s end, big enough to reveal detail in steady sky at high magnification. The planet rises in the southeast just before 2 a.m. local time at the beginning of the month and about 12:30 a.m. as June winds down. It lies in the constellation Aquarius for most of the month and passes into Pisces on June 24.
7-9 June. The waning gibbous Moon joins Jupiter and Saturn east of the ‘Teapot’ asterism in Sagittarius. Jupiter lies at the eastern end of the constellation while Saturn sits just over the border in Capricorn. The two big planets are just five degrees apart now, with brighter Jupiter to the west of Saturn. Both planets are in a good position for viewing in a telescope for the next few months. Jupiter shines at magnitude -2.6 and spans about 47”, while Saturn shines at a magnitude +0.3 and spans about 40” (including rings). The southerly location along the ecliptic favors southern-hemisphere observers, but northern stargazers can still detect detail on nights of good seeing.
12 June. Neptune is the most difficult planet to find, but once in a while a brighter object helps guide the way to seeing this distant 8th-magnitude ice giant. On the morning of June 12, look to much brighter Mars to find Neptune just 1.7o to the south. The pair lies near the waning gibbous Moon in the southeastern sky before dawn in the constellation Aquarius. At magnitude -0.2, Mars vastly outshines Neptune. The two planets fit nicely in a wide field of view of most small telescopes, and a little more magnification reveals Neptune’s tiny 2.4” disk and pale blue color. Both planets are on the way to opposition later this year, Neptune on September 11 and Mars on October 13.
13 June. Last Quarter Moon, 06:24
13 June. Look for the last-quarter Moon near the brightening planet Mars in the southeastern sky a couple of hours before sunrise.
19 June. Venus has emerged in the morning sky and today it makes a close approach to the slender crescent Moon in the northeastern pre-dawn sky. Venus hangs just off the unlit side of the Moon. The pair will be low, so a clear view of the northeastern horizon and is needed to pick these two out of the twilight glare. A pair of binoculars will help also. Once you find them, look upwards about ten degrees to try to spot the Pleiades.
20 June. The June solstice arrives at 21:44 UT marking the start of summer in the northern hemisphere and the start of winter in the southern hemisphere. This is the longest day in the north and the shortest day in the south. At solstice, the Sun appears to ‘stand still’ in its most northerly point in the sky before moving southward again. On this day at latitude 23o 26’ 12” N, the Sun appears directly overhead at mid-day.
21 June. New Moon, 06:41 UT. An annular eclipse of the Moon is visible from central Africa and southern Asia. In this event, the Moon is just a little too far to completely cover the face of the Sun and leaves a bright ring at the solar edge.
28 June. First Quarter Moon, 08:16 UT