Night Words for June: Venus, Mars cozy at dusk; Mercury, Jupiter and Saturn light up the dawn

Sun rises at 5:35 a.m. and sets at 8:24 p.m. on the 1st

Sun rises at 5:36 a.m. and sets at 8:34 p.m. on the 30th

Full Flower Moon on the 3rd

New Moon on the 18th

June is the month of seasonal transition from spring into summer.

Fittingly, the stars associated with both spring and summer are on display in the night sky in June: the spring stars are best viewed during the early evening hours, while those associated with summer dominate later at night, especially toward midnight.

Amazingly, even a small number of stars left over from winter are still visible shortly after nightfall in the first half of the month.

These include the two brightest stars of Gemini, Pollux and Castor, which are now setting in the northwest.

The sixth brightest star in the night sky, Capella in Auriga, lies to their right. All three stars will soon vanish into the evening twilight, not to return to the night sky until the fall.

The procession of bright spring stars starts with bluish-white Regulus in the constellation Leo. Regulus stands high in the southwest in early evening, and sets around midnight.

A slightly brighter star with similar color is Spica, which stands about halfway up in the south shortly after nightfall.

But the first star to burn through the evening twilight is Arcturus, the fourth brightest star in the entire sky, in the constellation of Boötes, the Herdsman.

Arcturus has a distinct yellowish-orange color, and lies high above Spica in the south at around 9 p.m.

To find Arcturus and Spica, first locate the Big Dipper, and follow the arc of the Dipper's handle outward until you encounter Arcturus, then continue on to meet Spica. Regulus, Spica, and Arcturus form the large "spring triangle."

To the east of Virgo lies the next zodiac constellation Libra, the Balances, whose two brightest stars are Zubenelgenubi and Zubeneschamali, the latter of which appears to have a greenish tint when seen through a telescope.

If the sky is especially dark where you live, try to locate the semicircle of stars representing the constellation Corona Borealis (Northern Crown) just a bit above and to the east of Arcturus.

In mythology, Corona Borealis represents the crown of Princess Ariadne, daughter of King Minos of Crete.

The crown's brightest star is bluish-white Alphecca, also known as Gemma. To the east of Corona Borealis is Hercules, thefifth largest constellation in our sky. The brightest star in Hercules is Rasalgethi, which is both a variable star and a double star.

One of the lesser known spring constellations is Canes Venatici, the hunting dogs, which passes nearly overhead in the early evening hours of June.

This tiny group was originally part of Ursa Major, but in 1690 Johannes Hevelius introduced it to represent a faithful pair of dogs to accompany Boötes.

Canes Venatici contains only one relatively bright star, Alpha Canum Venaticorum, better known as Cor Caroli, or "Heart of Charles."

The name was possibly bestowed by Edmond Halley in the late 1600s in honor of his king, Charles II. When viewed through a telescope, Cor Caroli is revealed to be a splendid double star, with the brighter component blue and the fainter one yellow.

The blue star is especially peculiar, showing evidence of a powerful magnetic field. The Cor Caroli system lies about 110 light-years from our solar system, and is important enough to be listed in astronomer Dr. James Kaler's book, "The Hundred Greatest Stars."

By late evening, as the stars of spring are descending toward the western horizon, the stars of summer are ascending above the eastern horizon.

The brightest of the latter category is bluish-white Vega, in the constellation Lyra, which is rising in the northeast.

Also rising in the northeast following Vega is Deneb, in Cygnus the Swan. And low in the east is the star Altair in Aquila the Eagle.

The trio of Vega, Deneb, and Altair form the "summer triangle." Yet another bright summer star is orangish-red Antares, in Scorpius, which is low in the southeast but getting higher.

In mid-June, Antares rises around 7:30 p.m. and crosses the south meridian just before midnight.

Venus and Mars adorn the western sky as darkness falls on June evenings, while Mercury, Saturn and Jupiter glow in the morning sky.

For the entire month of June, yellowish Venus blazes above the western horizon until well after evening twilight ends, and remains visible until it sets during the hour before midnight.

Early in the month, on June 4, Venus reaches its greatest eastern (evening) elongation with the sun, and later, on the 21st, thewaxing crescent moon passes just above and to the right of Venus as they descend together toward the northwestern horizon on that evening.

Venus sets around 11:45 p.m. on the 1st and an hour earlier on the 30th.

As June opens, Mars is in the middle of the dim constellation Cancer, to the upper left of brilliant Venus and to the far left of Gemini's two brightest stars Pollux and Castor.

On the 2nd, Mars passes directly in front of the famous "beehive" star cluster, which can easily be seen through binoculars or a small telescope.

Orangish Mars is distinctly fainter than Pollux but roughly the same magnitude as Castor.

Mars sets around 12:15 a.m. at the beginning of June, and by 11 pm at month's end. Mars will remain in the evening sky until itreaches conjunction with the Sun in mid-November.

Saturn ascends higher in the morning sky this June, and at month's end moves into the evening sky. Throughout the month of June, Saturn can be spotted moderately high in the south-southeast an hour or so before dawn.

Saturn rises by 1:30 a.m. on the 1st, and by 11:30 p.m. on the 30th.

Jupiter passed behind the sun (conjunction) in early April; it was too closely aligned with the sun to be easily seen until late May.

At the start of June, Jupiter rises before 4 a.m. and is easily spotted above the eastern horizon at dawn.

By month's end, Jupiter is rising by 2 a.m. and is high in the southeast during the dawn twilight.

Mercury reached greatest morning elongation with the sun on May 29, and as June opens Mercury is still in good position for viewing. It looks like a bright yellow star low above the northeastern horizon at dawn.

Mercury rises about 4:30 a.m. on the 1 st , and soon thereafter it begins to descend toward the horizon.

By month's end, Mercury has vanished behind the sun.

Earth reaches the summer solstice on June 21 at 10:57 a.m. when the Northern Hemisphere is tilted maximally toward the sun, marking the start of summer in the Northern Hemisphere and of winter in the Southern Hemisphere.

Astronomy question for June: What is "dark matter" composed of, and how is do we know it exists? (Answer will be provided in next month's column.)

Answer to last month's question: The center of the Milky Way contains a supermassive black hole with an estimated mass of 2.7 million suns, surrounded by an accretion disk of hot gas, which emits large amounts of infrared and radio waves. Most other galaxies also contain supermassive black holes; one of the biggest is the black hole at the center of the elliptical galaxy M87, with a total estimated mass of 6.5 billion suns!

Astronomical information is obtained from The Astronomical Almanac (2021-2025) by Richard J. Bartlett, and from Astronomical Calendar 2023 by Guy Ottewell, available online at https://www.universalworkshop.com/astronomical-calendar-2023.

For more information on the night sky, visit the Widener Observatory Stargazing website at http://www.widener.edu/stargazing. A set of free sky maps can be obtained at http://www.skymaps.com.

Sign up for email newsletters