Now that summertime in the Northern hemisphere is in full swing a whole new batch of constellations can be seen in the south. Although the ‘late birds’ among us will be rewarded with the best viewings in the little hours after midnight, the opportunity to add these less well-known patterns to your checklist ought to make a few moments of stargazing worth the effort.
Rising sufficiently high above the horizon for you to see most if not all of its stars, at 10pm Ophiuchus “The Healer and Surgeon” lies almost due south during July. This son of Apollo, also known as Aesclepius was born to a one-parent family and mostly raised by Chiron the centaur who taught him the ways of medicine. With an inverted ‘shield-like’ pattern and one protruding limb from the bottom right-hand corner considered sufficient to define the ‘Father of Medicine’ in the heavens, the remaining points of light running diagonally upwards on either side of the constellation actually belong to a separate constellation, that of a snake. As such Serpens is the only constellation of the night sky that has been divided in two, however that said, it is usually depicted by artists as being in the healer’s hands. To the left of Ophiuchus the snake’s tail can be seen, ‘Cauda’, and to the right ‘Caput’, the creature’s upper body and head, the last of which is formed from a small triangle of stars. According to legend, Ophiuchus’ skills at creating healing mixtures from the poisons of snakes and plants were so great, that he was even able to restore people to life. Despite this achievement earning him “death by thunderbolt” at the request of the jealous god of the Underworld, it also earned him Zeus’ clemency, along with restoration to life, immortality, and a place among the stars. For those with a good pair of binoculars, why not see if you can find a sample of one of the largest gravitationally-bound structures of the Universe, the cluster of galaxies known as IC4665 above the star in Ophiuchus’ left shoulder, Cebalrai (Beta Ophiuchi)?
Although light from our nearest star guarantees our celestial backdrop is in its palest mode at this peak of the season, one stellar treat that compensates us handsomely for the disadvantage is commonly known as the ‘Summer Triangle’. The beautiful simplicity of this shape makes a refreshing break from tracking down the dimmer and more complex of the constellations while its three very bright stars also highlight its shape to even the youngest of observers. So of the two star patterns we have looked at so far, this is our ‘early bird pattern’. Not only do the bright stars Vega, Deneb , and Altair ensure the triangle can be seen before 12am in July, the superstar trio are also bright enough to be spotted before dark. Sticking with our avian theme a little longer however, the first and brightest star in the isosceles triangle is in fact associated with a vulture.
With the triangle actually being an asterism and each of its stars in their own right belonging to three separate constellations, Vega, in the top right-hand corner and to the left of Hercules is found in the constellation of Lyra. Lyra or ‘the lyre’ was played by musician and poet, Orpheus. After his pronunciation on the death of his wife that he would never love another woman provoked the raving intoxicated females, the Bacchantes, to tear him limb from limb, his stringed instrument was thrown into the river. Zeus, the king of the gods, sent a bird to retrieve it and then ordered that they both be placed in the heavens, hence the constellation’s classic depiction of a lyre within the beak or claws of a vulture or eagle.
Residing in this modest little constellation is none other than the Ring Nebula. To find it, look approximately halfway along the diagonal between the two bottommost stars of the quadrangle, Sulafat and Sheliak. Despite the fact that through a small telescope or pair of binoculars your eyes will be deceived by the fuzzy planet-like disc (hence the name planetary nebula) of Messier 57, the inducement of seeing “with your own eyes” one of the most striking and famous of all deep-space objects should be little diminished. The world’s largest optical telescopes in fact reveal the fainter but true ‘eye-shaped’ cloud of debris thrown off by the star that once inhabited the centre of the nebula’s blue oxygenated ‘iris’.
But what of Vega itself? Although it ranks as the fifth brightest star of the heavens, in terms of those that can be seen from the northern hemisphere, Lyra’s brightest star bears the bronze medal for visual luminosity. Despite holding the historic astronomical title of being the first star ever to be photographed, back in 1850, it remains a star of mysteries. All stars, including the ‘foetus’ protostars (pre-ignition balls of gas and dust pulled together by gravity), spin. However, if our own eyes were capable of detecting Vega’s stellar movement we would discover that we’re actually looking ‘down’ on its rotational axis. In other words its axis of rotation or pole is actually pointing at our planet! Alongside this peculiarity is its chemical composition. As Vega contains only approximately a quarter of the metal content found in our Sun (note that the word ‘metal’ is used here in the manner peculiar to astronomers to mean a chemical element other than hydrogen or helium) This rather ‘alien’ characteristic makes it more akin to the distant stars residing in the large ‘halo’ encapsulating the Milky Way galaxy, yet it is not one of them.
So as you raise your eyes to the heavens to observe the great sights of the night sky in July, happy hunting and enjoy your interstellar voyage!
(Article by Nick Parke, Education Support Officer)