Glorious Venus grabs our attention once the Sun dips below the horizon, but don’t overlook Mars which is also visible at nightfall. This month, the two planets take turns visiting the Beehive cluster.
Venus’s stunning apparition in the evening sky, which began in December, will come to an end in just a few weeks. The dazzling Evening Star is clearly visible due west after sunset, but you’ll notice it appears lower and lower in the sky over the next few weeks: Between early and late June, Venus actually drops a dozen or so degrees with respect to the horizon at twilight, and the trend continues into July.
Despite its decaying position, Venus is still worth looking at through a small telescope, especially these days. On June 4, the lovely planet reaches its greatest elongation, 45 degrees east of our Sun. For a few evenings around this date, it appears as a “half-Venus,” 23 arc seconds in diameter. In fact, Venus has phases much like those of the Moon. As it catches up to us in its orbit over the following weeks, Venus transforms into an increasingly spectacular crescent: At the end of June, the planet appears as a thick crescent, 32% illuminated and 33 arc seconds in diameter. Venus’s appearance continues to change into July: On the 20th, a few evenings before it disappears in the twilight glow, the crescent Venus becomes even thinner (only 15% lit) but significantly larger, with a diameter of 45 arc seconds.
About one hour after sunset, as the sky grows darker and dotted with more stars, you’ll note the rather discreet presence of Mars, slightly higher and to the left of flashy Venus. The Red Planet has wandered far from Earth and dimmed considerably since its December 2022 opposition; to the naked eye, it appears as a somewhat faint, ordinary orange star that moves from one evening to the next. Unlike Venus, its small orange disc is now unremarkable when observed through an amateur telescope.
Rendez-vous with the Beehive
Mars currently shines solo in what resembles a kind of “void” in the string of constellations near the ecliptic, between Gemini (with its two brightest stars, Castor and Pollux) and Leo (with its brightest star, Regulus, and the Sickle star pattern). In light-polluted city skies, your eyes won’t detect anything in this area of space. Darker skies, however, would make it easier to spot the faint constellation Cancer. But take a look on a moonless night, when light pollution is virtually non-existent, and you’ll see a hazy patch of light, slightly bigger than the full Moon, right at the centre of the celestial Crab.
The Beehive cluster, or Messier 44, located 590 light-years away from us, is one of the closest open star clusters to our solar system, making it a relatively bright, spread-out object in the sky. Binoculars will provide a clear view of its brightest, magnitude 6 and 7 stars, whereas a wide-field telescope will reveal hundreds of stars. Based on detailed surveys, the cluster apparently contains more than 1,000 member stars, born from the same molecular cloud about 600 million years ago.
This object, known to humans since prehistoric times, was first documented by the Ancient Greeks; in traditional Chinese astronomy, the cluster is known as “the ghost.” In the first century CE, Ptolemy included it in his star catalogue, along with a handful of other nebulous objects. Galileo was the first to observe it in 1609 using his small telescope: He was able to detect a cluster of a few dozen stars. In 1764, Charles Messier included it as the 44th object in his famous catalogue.
In Europe, this cluster is known as the Manger, the translation of its Latin name Praesepe, which is often used in European publications. Two of the stars that frame the cluster and form the body of the celestial Crab are Asellus Borealis (Gamma Cancri) and Asellus Australis (Delta Cancri): “the Northern Donkey” and “the Southern Donkey” can be seen feeding out of this manger.
On our side of the Atlantic, however, this cluster is usually called the Beehive—a befitting image of swarming bees, wouldn’t you agree?
Due to its position in the sky, barely 1 degree above the ecliptic (the imaginary line that the Sun travels over the course of a year), the Beehive cluster also gets frequent visits from the main planets of the Solar System. That’s what’s happening in early June: On the evenings of June 1 and 2, Mars sails through the heart of the Beehive, but it’s also near the cluster’s edge on May 31 and June 3. This is a dramatic optical illusion, however, since the stars of the cluster are actually 20 million times further away than the Red Planet! Although Mars has dimmed significantly since its opposition in December 2022, this tiny orange dot of magnitude +1.6 is still about 100 times brighter than the cluster’s brightest stars and contrasts nicely with their bluish colour. After the sky grows dark enough, about 90 minutes after sunset, Mars and the Beehive can be found about 20 degrees above the western horizon. That means you’ll have a good hour to enjoy the scene before Cancer sinks too low on the horizon and the cluster’s stars are rendered invisible by atmospheric extinction.
Venus is, of course, also travelling through the constellations, as if it were chasing Mars. It pulls away from Gemini and, in turn, seems poised to dive into the apparently empty space of the constellation Cancer. On June 13, the Evening Star passes just north of the Beehive cluster but is also quite close to it on the evenings of June 12 and 14. Once again, it’s an illusion: The dazzling planet (magnitude –4.4) is in the foreground and the cluster’s stars are very far behind. Because the spring constellations sink lower in the west as the season progresses, the Beehive cluster and the planet now hang a mere 15 degrees above the horizon once darkness falls, around 10 p.m., effectively shortening the viewing window. The cluster’s stars are about 10,000 times dimmer than Venus—now that’s an extreme difference! The planet currently appears as a thick crescent, 44% illuminated and 26 arc seconds in diameter.
Lunar crescent, planets and solstice
After these fleeting encounters, Mars and Venus continue to dash eastward through the constellations. The quicker Evening Star steadily catches up to the Red Planet. On the evening of June 21, the lunar crescent lies a mere 3 degrees to the upper right of Venus, while Mars hangs 4½ degrees to the upper left, completing the triangle.
June 21 is also the day of the solstice, which occurs at 10:58 a.m. EDT. It’s the official start of astronomical summer in the Northern Hemisphere (and of Southern winter), marked by the year’s longest day of sunlight. However, the earliest sunrise occurs a few days earlier (June 16) and the latest sunset a few days later (June 28); check out our June 2021 archive for an explanation of these shifts.
Clear skies!
