June Sky Notes

The late Spring/early Summer skies contain a number of constellations which have their origins in the stories of one of the great heroes of the Ancient World. The constellation of Hercules can be seen almost overhead during June. The readily identifiable asterism (a shape within the constellation) of the “Keystone” stands out. Scanning the Western (right-hand) side of the Keystone with a good pair of binoculars will reveal a bright fuzzy patch. This is the object known as M13 in Messier’s Catalogue, although it was discovered by Edmund Halley (of comet fame). It is bright enough to see because it consists of stars. It is a special kind of star cluster known as a “Globular Cluster” because of its shape. It is a ball of, maybe Half a Million, stars that orbits around the centre of our Galaxy. There are many such Globular Clusters associated with our Galaxy and we have observed similar clusters associated with other galaxies.

In traditional pictorial representations, Hercules is always seen upside-down. This represents his emergence from the Underworld after completing his 12th Labour – taming the three-headed dog Cerberus. In fact, Cerberus was identified as a separate constellation within, what is now Hercules, during the 17th and 18th centuries.

The constellation of Leo, seen in the West, is said to represent the Nemean Lion, the subject of Hercules’ First Labour. The preceding constellations of Cancer and Taurus are also, sometimes related to Hercules. Taurus may represent the Cretan Bull which he was sent to capture whilst Cancer represents a crab that was sent to distract him from completing yet another Labour, by Hera, the goddess who had instigated the tasks.

That Labour was the defeating of the Lernean Hydra. Hydra is the constellation hugging the South-West horizon, and represents this mythical monster. Hercules had to cut off the many heads of this creature in order to defeat it. However, every ime one head was severed, two more grew in its place. Our hero had to decapitate the head and then cauterize the wound before it was replaced.

This is where the crab comes in, trying to distract Hercules from completing the task successfully. However the unfortunate crustacean was crushed underfoot during the struggle. Hera then placed it in the sky as a reward for its loyalty to her.

The rising Summer constellations seen in the Eastern sky, Aquila(the Eagle), Cygnus (the Swan) and Lyra (the Lyre, but used to be known as The Vulture) are also connected to the myth of Hercules. In one version of the tradition, they represent the Stymphalian Birds, the subject of another of the hero’s Labours.

These stories demonstrate the real reason for the constellations. They are seasonal, visual reminders to the storytellers of an oral tradition dating back thousands of years. Today we do not always see how the shapes in the stars manage to represent their namesakes, but we still remember the stories.

Also in our skies at the moment we can see the constellation Corona Borealis, just to the West of Hercules. This constellation is formed by a distinct curve of stars. At the time of writing, astronomers are still awaiting the nova event predicted for the star T corona Borealis. This star is of a type that undergoes repeated nova-like explosions, brightening by some 10 orders of magnitude, and so the star has been  under careful scrutiny for many months. No less than four prediction deadlines have been passed with no sign of change in the star. We are currently within a prediction parameter that runs from “mid-February 2024 – September 2026” however, there was also a prediction made in 1946 that the so-called Blaze Star would erupt again in 2026-2027.  We will just have to keep all eyes on the sky and hope that it is not cloudy when it eventually happens.

Sky Notes

Sky Schedule

Please note all times given in this article are in GMT so remember to add an hour to get the time in BST which started on Sunday 29h March.

Sun: The Sun is never very far below the horizon at night throughout June and into July, so it never gets astronomically dark, and this is not the best time for observation of faint fuzzy objects. However stars and planets can still be observed particularly around midnight when the sky is at its darkest.  The Milky Way is visible from dark sites stretching across the Northern horizon.

The Summer Solstice (longest day of the year) occurs on June 21st

Mercury:  Mercury lies close to the Western horizon and is seen only with difficulty in a still sunlit sky. NEVER LOOK DIRECTLY AT THE SUN! Mercury reaches its greatest distance from the Sun 9elongation) on 15th and this would be the best time to try and find this elusive planet. Ensure that your direct view to the Sun is obscured in some way.

Venus:  Venus is seen a little higher in the sky than Mercury and is a little further from the Sun. However it still lies close to the Western horizon seen against the background stars of Gemini. On June 9th Venus will be seen so close to Jupiter that they will almost seem to touch. Such a close conjunction of the two brightest planets is one possible explanation of the “star of Bethlehem”.

Mars:  Mars is visible low in the Eastern sky, rising about 2.30 in the morning and visible for a short while before sunrise. On 12th Mars will appear close to the Moon.

Jupiter:  The giant planet is getting lower in the Western sky and will soon be lost in the glare of the Sun. On 9th Jupiter will lie very close to Venus. This would make a good subject for an image, if you have a low and clear enough Western horizon. On 17th Jupiter will be seen close to the Moon.

Saturn: The ringed planet rises around midnight this month and may be visible for a short while before sunrise. On 10th the Moon will lie close to Saturn making the ringed planet easier to pick out.

Uranus and Neptune: Both of the outer planets are now too close to the Sun to be visible.

Meteor Shower:  There are no major meteor showers this month, but you could still see stray (sporadic) meteors and meteors from a couple of minor showers; the Arietid shower from 14th – 24th occurs during the daytime and the Bootid shower which peaks on 27th. Neither are strong showers and produce few meteors, although the Arietids have been predicted to be more numerous this year.

Noctilucent Clouds:  It may seem anachronistic for astronomers to be interested in clouds, but these rare apparitions are best seen at this time of year.  Noctilucent clouds are so high (over 80 km) in the atmosphere that they are able to reflect sunlight even when the Sun is well below the horizon.  The tiny ice crystals that make up the clouds reflect bluish-white light that stands out against the gloaming sky.  They are typically seen 1 ½ to 2 hours after sunset low in the Northwest or before sunrise low in the Northeast.

Moon: The Last Quarter Moon occurs on June 8th with New Moon on June 15th.  First Quarter follows on 21st and the Full Moon occurs on June 29th.