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What’s In August’s Night Skies

Planets:

Both Mercury will reappear in the early August morning sky around 06:00 am (AWST) for the first part of August. It’ll also reach its greatest elongation in the East on the 10th of August at 07:00 am (AWST) and then will start to head back towards the sun

Jupiter, the king of the planets can be still be found in the Ophiuchus (The Serpent-bearer) Constellation this month. It’ll be viewable at the start of the night throughout the month, at the beginning of August, Jupiter will set at 03:35 am (AWST) and by the end of the month it’ll at 01:39 am (AWST). Saturn is still below Jupiter in the Constellation of Sagittarius (The Centaur with a Bow) and it’ll be viewable at the start of the night throughout the month. At the beginning of August, Saturn will set at 05:48 am (AWST) and by the end of the month it’ll at 03:45 am (AWST).

Mercury on the 15/08/19 at 06:00 am. Image Credit: Stellarium Mercury near it's greatest elongation in the East on the 10/08/19 at 06:00 am. Image Credit: Stellarium Jupiter and Saturn on the 15/08/19 at 08:00 pm. Image Credit: Stellarium

Uranus can be found in the Constellation of Cetus (The Sea Monster) in the early evening this month. It’ll rise at 00:28 am (AWST) at the start of August and by the end of the month it’ll rise at 10:25 pm (AWST). Neptune, the last planet in our Solar System can be found in the early morning sky in between the Constellations of Aquarius (The Water Bearer), Cetus (The Sea Monster) and Pisces (The Fish) the whole of August. The planet will rise at 08:38 pm (AWST) at the beginning of August and by the end of the month at 07:17 pm (AWST)

Uranus on the 15/08/19 at 03:00 am. Image Credit: Stellarium Neptune on the 15/08/19 at 00:00 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.

  • 06/08/19 – Conjunction of the Moon and Spica (Where to look)
  • 09/08/19 – Conjunction of the Moon, Antares and Jupiter (Where to look)
  • 10/08/19 – Conjunction of the Moon, Antares, Jupiter and Saturn (Where to look)
  • 11/08/19 – Conjunction of the Moon, Antares, Jupiter and Saturn (Where to look)
  • 12/08/19 – Conjunction of the Moon and Saturn (Where to look)
  • 24/08/19 – Conjunction of the Moon and Aldebaran (Where to look)
  • 25/08/19 – Conjunction of the Moon, Aldebaran and Betelgeuse (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 5 – 10 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, especially this year with there being no Moon this year. For Perth shooting star lovers, it’s best to go out and look north at 6 am.

The Perseids on the 14/08/19 at 05:30 am. Image Credit: Stellarium The Perseids from the Northen 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, in fact, 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 15/08/19 at 09:00 pm. Image Credit: Stellarium Albireo. Image Credit: Palomar Observatory/STScI/WikiSky

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 which contain many hot blue stars, like the Pleiades, are considerably younger.

Ptolemy Cluster on the 15/08/19 at 09:00pm. Image Credit: Stellarium Ptolemy Cluster. Image Credit & Copyright: Lorand Fenyes

Trifid and Lagoon Nebulas:

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

The Trifid Nebula is an emission (pink) and reflection (blue) nebula, with open star cluster, found in Sagittarius. 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 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 actually a cluster of four star systems, two of which are close binaries, making 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 15/08/19 at 09:00 pm. Image Credit: Stellarium Trifid Nebula and Lagoon Nebula. Image Credit: Paulo Cacella

Omega Nebula:

The Omega Nebula is located in the Sagittarius constellation. This emission nebula is regarded as one of the brightest and most massive star-forming regions of the Milky Way. Within the nebula, the radiation from an open cluster of ~35 hot, young stars heats the surrounding gas to incandescence. There could be as many as 800 stars in the associated cluster.

The nebula was first discovered in 1745 and recorded by Charles Messier in 1764, and it’s so named because it appears like the Greek letter Omega. Alternatively, it may be seen as a horseshoe with a “tail” to one side giving it, perhaps, a swan’s neck appearance. It is also referred to as the Swan, Checkmark, Lobster and Horseshoe Nebula.

Omega Nebula on the 15/08/19 at 09:00 pm. Image Credit: Stellarium M17 - Omega Nebula. Image Credit: Putman Mountain Observatory

47 Tucanae:

47 Tucanae (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”. Omega Centauri 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 2018, indirect evidence for a likely intermediate-mass black hole in 47 Tucanae was announced.

47 Tucanae on the 15/08/19 at 9:00 pm. Image Credit: Stellarium 47 Tucanae. Image Credit & Copyright: Mike O'Day

Phases of the Moon:

August 2019 Moon phases

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