Find out what to go out and look at this month

Planets:

Mercury is visible very low in the Western early evening sky from the middle of August, appearing in the constellation of Leo (The Lion) before quickly moving into the constellation of Virgo (The Virgin) and joining Venus. Venus and Mars will also be visible low in the Western early evening sky in August. Both planets will start the month off in the constellation of Leo, but they’ll go their own way we move through August. Venus will move into the constellation of Virgo while Mars stays in the constellation of Leo and in the middle of August, starts to enter the Sun’s glare.

Jupiter and Saturn can be found in the Eastern evening sky. Jupiter can be found in the constellation of Aquarius (The Water-Bearer) while Saturn can be found in the constellation of Capricornus (The Sea-Goat) during August. Both planets will be viewable throughout the night and will reach opposition (On the opposite side of the Earth from the Sun) this month with Saturn reaching opposition on the 2nd of August and Jupiter on the 20th of August.

Uranus can be found in the late evening in the constellation of Aries (The Ram). At the beginning of August, Uranus will rise at 01:04 am (AWST) and by the end of the month, it’ll rise at 11:03 pm (AWST). Neptune will be viewable as well in the late evening between the constellation of Aquarius and the constellation of Pisces (The Fish). At the start of August, Neptune will rise at 08:57 pm(AWST) and by the end of the month, it’ll rise at 06:55 pm (AWST).

Mercury, Venus and Mars on the 15/08/21 at 06:30 am. Image Credit: Stellarium
Jupiter and Saturn on the 15/08/21 at 08:30 am. Image Credit: Stellarium
Uranus and Neptune on the 15/08/21 at 03:00 am. Image Credit: Stellarium

Conjunctions And Occultation:

Conjunctions involve object(s) in the Solar System and/or more distant objects, such as a star. It’s an apparent phenomenon in which multiple objects which aren’t close together appear close in the sky and it’s caused by the observer’s perspective. An occultation is an event that occurs when one object is hidden by another object that passes between it and the observer.

  • 03/08/21 – Conjunction of The Moon and Aldebaran (Where to look)
  • 11/08/21 – Conjunction of The Moon and Venus (Where to look)
  • 13/08/21 – Conjunction of The Moon and Spica (Where to look)
  • 16/08/21 – Conjunction of The Moon and Antares (Where to look)
  • 19/08/21 – Conjunction of Mercury and Mars (Where to look)
  • 20/08/21 – Alignment of The Moon, Jupiter and Saturn (Where to look)
  • 21/08/21 – Conjunction of The Moon, Jupiter and Saturn (Where to look)
  • 22/08/21 – Conjunction of The Moon and Jupiter (Where to look)
  • 31/08/21 – Conjunction of The Moon and Aldebaran (Where to look)

Astronomical Events This Month:

The Perseids:

The Perseids meteor shower is once nearly upon us. With the peak night occurring on the night of the 12th/13th, this meteor shower has been observed for at least 2,000 years now and is connected with the comet Swift-Tuttle, which orbits the sun every 133 years. Every August, The Earth passes through the debris field left by the comet’s tail, which consists of ice and dust that can be over 1,000 years old. This debris field will enter The Earth’s atmosphere and burns up to create one of the best meteor showers of the year.

The Perseids can be seen all over the sky in the Northern Hemisphere. People with sharp eyes will be able to see that the meteors appear to come from the constellation Perseus and that’s where they get their name from. The field will start to hit The Earth from about mid-august, with it finishing up towards the end of August. At its peaks which occur around the 12th and 13th of August, The Earth can expect to be hit with rates often exceed 100 meteors per hour.

Unfortunately for us in Australia and especially for Perth, the Perseids meteor shower is very very low on the horizon in the North around 6 am and if we’re lucky we’ll be able to see at best a couple of meteors per hour due to the fact we are so low in the Southern Hemisphere. It’s a real shame as in the Northern Hemisphere, they usually will see anywhere from 115 to 170 meteors per hour and this year the Moon is a New Moon phase so we don’t have to worry about the light pollution from it. For Perth shooting star lovers, it’s best to go out and look very low in the north at 6 am and it’s best to be at of Perth with no light pollution.

The Perseids on the 13/08/21 at 06:00 am. Image Credit: Stellarium
The Perseids from the Northern Hemisphere. Image Credit: Space.com

Things To Look At This Month:

Albireo:

Albireo is a double star that is 390 light-years away from us located in the constellation Cygnus. Albireo is the “beak star” in Cygnus the Swan. The origin of the name is through several mistranslations between Greek, Arabic and Latin. It is a good wide double star with strong colour contrast, possibly the best available to modest telescopes. It is low in the North and only available for a few months of the year during the late winter and spring. The primary star is yellow/amber in colour whilst its companion is blue/green.

The primary star is a close binary also, however, it is too close and faint to detect without very large telescopes and excellent observing conditions. The stars revolve around one another in about ~100 000 years. The primary star is ~5 times the mass and ~1 200 times brighter than the sun but with a cooler surface temperature of ~4 100 K. The secondary star is ~3.2 times the mass and ~230 times the brightness of the sun with a surface temperature of ~12 000 K.

Albireo on the 15/09/21 at 09:00 pm. Image Credit: Stellarium
Albireo. Image Credit: Palomar Observatory/STScI/WikiSky
Trifid And Lagoon Nebulas:

The Trifid Nebula (M20 & NGC 6514) and Lagoon Nebula (M8 & NGC 6523) can be found close together in the constellation of Sagittarius.

The Trifid Nebula is an emission (pink) and reflection (blue) nebula, with an open star cluster. The Trifid (Meaning “divided into three lobes”) comes from the three-pronged dark lanes (dark nebulae) through the nebula that blocks off the light behind. The nebula is 2,660 light-years away and is 15 light-years across.

The central star formation “nursery” where hot young stars power the emission nebulae. Infrared telescopes have shown there are 30 embryonic and 120 newborn stars not yet bright enough to emit light in the visible light part of the light spectrum. The new stars are very young at 400,000 years old with the central star in the nebula being a cluster of four-star systems, two of which are close binary stars, so there are six stars in all.

The Lagoon Nebula is, sometimes called the “Hourglass Nebula” (not to be confused with the true “Hourglass Nebula” in the constellation of Musca), is a very young nebula, perhaps less than 10,000 years. The nebula is further away than the Trifid Nebula at 4,100 light-years away and it’s a lot bigger with the nebula being 100 light-years across and 50 light-years high. It is one of the finest and brightest star-forming regions in the sky and contains many “Bok globules”, which contain dense cosmic dust and gas from which star formation may take place. The central emission area is energised by a bright ultraviolet “O4” class star and it’s a relatively easy object for amateur astrophotographers.

Trifid and Lagoon Nebulas on the 15/08/21 at 09:00 pm. Image Credit: Stellarium
Trifid and Lagoon Nebulas. Image Credit: Perth Observtory Volunteer Andrew Lockwood
Ptolemy Cluster:

The Ptolemy’s Cluster (M7 & NGC 6475) is a large open cluster near the sting of the tail of the constellation of Scorpius. While it’s 980 light-years away from us, it’s large enough to be seen with the unaided eye in a dark sky and is a nice sight in binoculars. The cluster is 25 light-years across, and it contains around 100 stars in total. It was first described by the Greek-Roman astronomer Ptolemy in 130 AD from which it gets its common name of Ptolemy’s cluster. The colour of the stars in this cluster is predominately yellow, indicating this is an older cluster, with an estimated age of 260 million years. Clusters that contain many hot blue stars, like the Pleiades, are considerably younger.

Ptolemy Cluster on the 15/08/21 at 09:00pm. Image Credit: Stellarium
Ptolemy Cluster. Image Credit & Copyright: Lorand Fenyes
47 Tucanae:

47 Tucanae or NGC 104 is the second-largest and second brightest globular cluster in Milky Way. The Globular cluster is 16,000 light-years away from us and is located in Constellation Tucana (Named after the Tucan bird) and it’s a naked eye ‘star’ and clearly visible in binoculars as a ‘fuzzy blob’. 47 Tucanae contains at least 1 – 2 million stars and the cluster has a diameter of roughly 120 light-years and the stars are roughly 10 billion years old. The average distance between the stars at the centre is around 10% of a light-year or more than 100 times the diameter of our solar system. In February 2017, indirect evidence for a likely intermediate-mass black hole in 47 Tucanae was announced.

47 Tucanae on the 15/08/21 at 09:00pm. Image Credit: Stellarium
47 Tucanae. Image Credit & Copyright: Mike O'Day

Phases Of The Moon:

August 2021 Moon phases