Today we have a batch of cool astronomy photos from reader Chris Taylor. Chris’s captions are indented, and you can enlarge the photos by clicking on them. His captions are very good, and I highly recommend enlarging the photos to see things like nascent comet tails and the moons of Jupiter, which are very clear in the enlarged photo but harder to see on this post itself.
Not exactly wildlife, but I hope these might be of interest. All of these photos were taken by me from my own property, apart from the first one.
Starting off with our own galaxy, which we see as the Milky Way. Having lived in both the Northern and Southern hemispheres, I have to say that the part visible from the south is much more impressive than the north, so I will show some of the highlights.
The first photo is looking south across the water of the Coorong, a long coastal lagoon on the east of the Great Australian Bight. The Milky Way is visible right down to the horizon. The brightest star in the middle of the photo is Alpha Centauri. This, together with its near neighbour Beta Centauri, form the pointers to the Southern Cross, Crux. The long axis of the cross points towards the southern celestial pole, which is out of the frame of this picture.
Taken from my own backyard, the next photo is a closer look at the Milky Way in Centaurus and Crux. Alpha and Beta Centauri are at the bottom right of the frame, with the Southern Cross to the right of centre. Easily visible in this shot is the Coalsack, a dark nebula where dust is obscuring the light from more distant stars. In indigenous culture, the dark areas of the sky formed constellations as well as the bright stars. In some groups, the Coalsack was the head of an Emu in the sky, but in others it was the head of a hunter. Also visible as a bright fuzzy star at the bottom left of centre is the globular cluster Omega Centauri.
Focusing more closely on the constellation Crux, the Southern Cross now, this photo shows the constellation in more detail. The Coalsack is at the bottom, with the brightest star Acrux at the edge of the dark area. There are another four bright stars that make up the kite shape of the cross, and which are represented on the Australian flag. At the bottom of the photo is what appears to be another bright star. To the naked eye this seems rather dimmer, and it was given the designation kappa Crucis. But it is in fact a cluster of about 100 young hot giant stars. When its true nature was realised, it was given a new name, the Jewel Box cluster. It is a beautiful sight in a telescope.
Seen from my home latitude, the centre of our galaxy passes straight overhead at times. This next photo shows the Milky Way in the constellations of Scorpius and part of Sagittarius. Once again, alpha Centauri is visible as the bright star just over the roof of the house. Below and right of centre is the bright red star Antares. The Milky Way is very wide and bright in this direction and is crossed and split by many dark lanes of dust, but there are also many bright clusters of stars.
A closer look into this region of the sky shows some of the clusters and nebulae. On the left side of the frame are the bright stars of the “tail” of Scorpius, and left of centre are two open clusters named Messier 6 and 7 (M6 and M7). These were catalogued by the french astronomer Charles Messier in 1780s who was searching for comets, but made a catalogue of objects that could be mistaken for a comet. M6 is the brighter spot left of centre. It is a cluster of about 150 hot blue stars, plus one red one. The colours of the stars can just be made out. M7 is smaller and fainter below centre. On the right are two areas of nebulosity. The brightest one can be seen as a fuzzy spot surrounding a number of blue stars. This is the Lagoon Nebula, M8, a giant cloud of interstellar gas and dust shining by reflected light from the stars embedded within the nebula. It is in the region of 5000 light years from earth. Close by is M20, the Trifid nebula. These nebulae are areas where stars are forming from the hydrogen gas making up the clouds.
The last picture of the Milky Way is centred on the eta Carina nebula, as it rises over the corner of my house. Eta Carinae is a binary system of two (possibly more) stars. The primary is one of the most massive and most luminous stars known; it has a mass of over 100 times that of the sun, while its luminosity is as much as 4 million times the Sun’s.
Our galaxy is accompanied by a number of smaller, satellite objects. This includes the two Magellanic Clouds. These are named for the explorer Ferdinand Magellan, who referenced them in his writings, although he was not even the first European to describe them. From my home, the clouds are easily visible, looking like spots of the milky way that have become detached. In fact, they are dwarf galaxies in their own right. The Large Magellanic Cloud is the largest of all the satellites, and it is now classed as a Barred Spiral; the bar and at least one spiral arm can be seen in this photo. It is about 160,000 light years from Earth. The bright spot at the centre is the Tarantula Nebula, an enormous area of active star formation.
Also satellites of our galaxy are the Globular Clusters. Globular clusters are collections of anywhere from tens of thousands to millions of stars that are packed into a dense spherical agglomeration due to their mutual gravity. These clusters are then able to orbit the centre of the galaxy as a single unit. Omega Centauri, which we saw in a previous photo, is the brightest one visible from earth. Messier 15 is another of the clusters catalogued by Charles Messier in the 1740s. This one is in the constellation of Pegasus and being away from the plane of our galaxy has many fewer stars close by. In my photograph the individual stars that make up the cluster – there are well over 100,000 – are not individually, but form a fuzzy halo around the central condensation of the cluster.
Moving closer to home, here are some photographs of objects in our own Solar System. The first ones were taken on 01 May 2022. Before dawn on that day, I got up to record the close conjunction of the two brightest planets in the sky, Jupiter and Venus as they appeared only 0.2 degrees apart – half the diameter of the Moon. The pair made an incredible sight, far outshining anything else in the sky as they rose over the hills to the east of my place.
But also on this day was another event – five of the planets were visible in a line in the eastern sky. At the bottom are Jupiter and Venus, higher up towards the centre is Saturn and the red planet Mars in at the top of the frame. The fifth one was Neptune, halfway between the bright planets and Saturn. But it is just visible on the photo as a couple of blue pixels, you have to look really hard to find it!
The last photo is zoomed in to Jupiter and Venus. Three of the Jovian moons are visible, at the top is Callisto, closer to the planet is Io, and on the other side is Europa.
I also managed to photograph two of the wandering comets. First is Comet C/2021 A1 aka Comet Leonard. This photograph was taken in January 2022 when the comet had already passed the closest to the Sun in its orbit, and a long though quite dim tail had developed. This comet was found to have had a hyperbolic orbit, which meant that the orbit was open and the comet would never return to the inner solar system. As it happened, it never got that far out from the Sun. As it rushed through past the inner planets, the nucleus of the comet broke up, and with the heat from the Sun evaporating more of the ice and other volatile material, the comet vanished from view in March 2022.
Another reasonably bright was Comet C/2022 E3 or Comet ZTF. On the morning of 11 Feb 2023, it passed between the Earth and Mars, when I was able to record the event. Mars is the reddish blob at the top of the frame, very overexposed, while the comet is bottom centre. There is a small tail forming around the core of the comet which appears green in this photo. That green colour was the result of Carbon C2 molecules evaporating off the surface of the nucleus. As the sunlight energises the molecules, they emit light at this frequency, which gives the characteristic colour.
