Skylights: June 2023

The shortest nights are upon us in June, with the solstice occurring at 10:57am EDT on the 21st. The earliest sunrise of the year occurs at 5:10am EDT on the 14th, and the latest sunset occurs at 8:25pm EDT on the 27th. The nights in between offer less than four hours and thirty minutes of astronomical darkness.

June begins with our two evening planets, Venus and Mars, in notable positions. First, brilliant Venus lies in a line with Castor and Pollux, in Gemini, as it leaves the winter stars behind. And Mars, which has been in our evening sky for the past 10 months, moves through the Beehive Cluster, M44, in Cancer, from the 1st through the 3rd.

The Full Strawberry Moon occurs late on June 3. Moonrise is at 8:14pm, one minute before sunset. Note the Moon’s position just 2.2° east of Antares in Scorpius. Moonset occurs at 5:09am on the 4th, about 3 minutes before sunrise.

The Moon is last quarter on the 10, new on the 17th, and first quarter on the 26th. On the 27th, it is 2.3° east of Spica, in Virgo.

Venus is the planet to watch in June’s evening sky. As the month progresses, it will appear to approach Mars, though it will never quite catch up to the Red Planet this time, coming to within 3.5° west of it on the 30th.

On the 3rd, Venus will be 50% illuminated, appearing as a “half-moon” phase, 23 arcseconds across. From now through conjunction in August, it will appear as a crescent.

Venus reaches its greatest elongation of 45° east of the Sun on the 6th, and passes through the northern portion of the Beehive Cluster, M44, in Cancer, on the 13th.

By the end of June, Venus will be just 0.5 AU from Earth, and will show a large, 34-arcsecond, 32% illuminated crescent in a telescope.

Mars is just over 2 AU from Earth at the beginning of June. Its tiny globe, just over 4 arcseconds across, is barely larger than Uranus appears when it is near opposition. Although Mars is now quite distant, it still shines brighter than the stars of the Big Dipper. After passing through the Beehive Cluster at the beginning of the month, it moves into Leo on the 20th, and, along with Venus, is joined by the crescent Moon over the following two nights. On the 21st, the waxing crescent Moon, Venus and Mars will lie within a 6° circle. This will be a fine view in binoculars.

June is the last month to observe Mars in a dark evening sky, as it will soon be slipping into the twilight glow.

Ceres continues its southeasterly motion through Virgo during June, moving approximately along the line connecting Denebola (beta Leonis) and Spica (alpha Virginis). The dwarf planet fades from magnitude 8.2 to 8.6 as its distance increases from 2.1 to 2.5 AU from Earth over the course of the month.

Saturn, in Aquarius, rises just before 1:30am EDT at the beginning of June, and becomes an evening planet later in the month, as it begins rising before midnight during the final week of June. On the 18th, Saturn is stationary.

Jupiter lies in Aries, and rises at 3:30am EDT at the beginning of June, and just before 2:00am on the last morning of the month. On the 14th, the 25.8-day crescent Moon lies just 1° to its northeast.

Uranus, in Aries, is too low for observation until later in the month. It is located 2.8° north of Mercury on the 4th, and a close pairing with the 26.8-day crescent Moon occurs on the 15th, with the Moon’s Earthshined globe passing just 0.8° north of the ice giant.

Neptune is in Pisces, rising just after 2:00am on June 1, and just after midnight on June 30. The distant ice giant is located just over 1° east-northeast  of 5th magnitude 20 Piscium, which itself is located 4.8° south of lambda Pisces, the southeasternmost star of  the Circlet asterism. On the 11th, the wide crescent, 22.7-day Moon is 2.7° south of Neptune. Neptune reaches western quadrature on the 18th.

Dwarf planet Pluto rises around midnight, and can be found, with a large telescope, 1.3° SE of globular cluster M75 in Sagittarius.

This month’s morning apparition of Mercury is one of the year’s least favorable, as the fleeting innermost planet remains low during its entire western elongation, which began in late May, and ends with its superior conjunction on July 1. It is at its best position during the first week of June, when it rises about an hour before sunrise. 

On the 16th, the very old 27.8-day crescent Moon lies between Mercury and the Pleiades.

Turning to the stars overhead, we find the Big Dipper high in the north during early evenings. This placement is fortunate, as there is a new supernova located in one of the northern sky’s better known galaxies, Messier 101. M101 is a face-on spiral galaxy, not too different from the Milky Way. It is located 21 million light years away, just off the handle of the Big Dipper.

21 million years ago, the core of a giant star collapsed when its internal fusion was no longer sufficient to hold it together. The collapsing core resulted in the entire star falling in onto itself, compressing its internal layers to the point where they could no longer hold up, resulting in a catastrophic explosion, shredding the star. The resulting outburst, known as a Type II supernova,  outshines the host galaxy, usually for several weeks. 

The supernova in M101, known as  SN 2023ixf, was discovered on May 19 by amateur astronomer Kōichi Itagaki, who has no fewer than 170 such discoveries to his name. In the days following its initial appearance, the supernova has brightened to magnitude 11.1, which puts it within view of even small telescopes. As it slowly fades over the coming weeks, it will remain easily visible, especially when the Moon leaves the sky during the second week of June, and its position in Ursa Major remains fairly high in our sky.

To find M101, start at Mizar and Alcor, the famous double star located in the bend of the handle of the Big Dipper. Draw a line from Mizar, through Alcor, and continue about seven times the gap between the two stars. You will land at the end of a flat, four-star zig zag of 5th and 6th magnitude stars that points away from the bowl of the Big Dipper. This is the “Mizar-M101 line.” Follow this line to the fourth, and last star, then turn east, away from the handle of the Big Dipper, at the same angle and distance that the beginning of the line is to Mizar. This relatively empty area of sky, when viewed under medium magnification, will reveal the diffuse glow of the face-on galaxy. SN 2023ixj is just east of the nucleus of the galaxy, on the side opposite Mizar.