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What’s In October’s Night Skies

Planets

Mercury will be low in our Western sky close to Venus. Both planets will move from the Constellation of Virgo (The Virgin) into the Constellation of Libra (The Weighing Scales) in the middle of the second week. Mercury will also reach its greatest elongation in the West on the 20th of October at 12:00 pm (AWST) and will then start heading back towards the sun. Jupiter and Saturn can be found above Mercury and Venus on either side of the Sagittarius Arm of the Milky Way with Jupiter in the Constellation of Ophiuchus (The Serpent Bearer) and Saturn in the Constellation of Sagittarius (The Archer).

Uranus will be viewable in the early evening in the Cetus (The Sea Monster) Constellation. At the start of October, the planet will rise around 8:19 pm (AWST) and by the end of the month above the horizon before nightfall. Neptune will be viewable straight at the beginning of the night in the Constellation Aquarius (The Water Bearer) Constellation. At the start of October, the planet will set around 05:09 am (AWST) and by the end of the month it’ll set around 03:09 am (AWST).

Mercury, Venus and Jupiter on the 15/10/19 at 07:30 pm. Image Credit: Stellarium Mercury near its greatest elongation in the West on the evening of 20/10/19. Image Credit: Stellarium
Jupiter and Saturn on the 15/10/19 at 08:30 pm. Image Credit: Stellarium Uranus and Neptune on the 15/10/19 at 08:30 pm. 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.

  • 02/10/19 – Conjunction of the Moon, Jupiter and Antares (Where to look)
  • 03/10/19 – Conjunction of the Moon, Jupiter and Antares (Where to look)
  • 04/10/19 – Conjunction of the Moon, Jupiter, Saturn and Antares (Where to look)
  • 05/10/19 – Conjunction of the Moon and Saturn (Where to look)
  • 06/10/19 – Conjunction of the Moon and Saturn (Where to look)
  • 18/10/19 – Conjunction of the Moon and Aldebaran (Where to look)
  • 21/10/19 – Conjunction of the Moon, Pollux and Castor (Where to look)
  • 29/10/19 – Conjunction of the Moon, Mercury and Venus (Where to look)
  • 30/10/19 – Conjunction of the Moon, Mercury, Venus, Jupiter and Antares (Where to look)
  • 31/10/19 – Conjunction of Mercury and Venus (Where to look)
  • 31/10/19 – Conjunction of the Moon and Jupiter (Where to look)

Astronomical Events This Month:

The Orionids Meteor Shower

The Orionids Meteor Shower has been observed for at least 200 years now and they’re caused by The Earth flying through the debris left over from Comet Halley’s tail. They’ll appear to be coming from the Orion constellation which is where the meteor shower gets its name from.

The debris field started hitting The Earth around the 2nd of October and it’ll finish up towards the 7th of November. The meteor shower will peak on the night of the 21st and 22nd of October, and you should expect to see up to 15 meteors per hour this year due to the Moon being almost a Last Quarter Moon.

The best time to view the Orionids is between 02:00 am and 05:00 am as. If you do get up at those ungodly hours to look at the meteor shower, you need to look directly east around midnight and then towards the North as it gets closer to sunrise.

The Orionids on the 24/10/19 at 4:00 am. Image Credit: Stellarium A composite of the Orionids meteor shower. Image Credit: Slooh Observatory

Things to Look at This Month:

Tarantula Nebula:

The Tarantula Nebula is an Emission Nebula which isn’t even located in our galaxy, but in one of our galaxies satellite galaxies, the Large Magellanic Cloud. The Nebula is some 160,000 light-years away from our Solar System and is 300 light-years across. This Nebula is an extremely luminous object, Its luminosity is so great that if it were as close to Earth as the Orion Nebula, the Tarantula Nebula would cast shadows and take up 60% of the horizon. It’s is the most active starburst region known in the Local Group of galaxies, this is because the nebula resides on the leading edge of the Large Magellanic Cloud where ram pressure is stripping, and the compression of the interstellar medium likely resulting from this, is at a maximum.

Tarantula Nebula on the 15/10/19 at 9:00 pm. Image Credit: Stellarium Tarantula Nebula - Image copyright: Roger Goom - astrophotography.com.au
Ptolemy’s Cluster:

Ptolemy’s Cluster or M7 is a large open cluster near the sting of the tail in Constellation Scorpius. It is large enough to be seen with the unaided eye in a dark sky and is a nice sight in binoculars. It contains around 100 stars in total, with 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. In comparison, clusters with many hot blue stars, like the Pleiades, are considerably younger.

It was described by the Greek-Roman astronomer Ptolemy in 130 AD from which it gets its common name of Ptolemy’s cluster. Open clusters are the end result of an emission nebula, such as the Orion Nebula (M42) or the Tarantula Nebula (NGC 2070). Over time the biggest stars in the cluster blow away the surrounding dust and gas that the cluster was born from, leaving a cluster of several hundred to several thousand stars that travel together within the galaxy. Older clusters are gradually scattered after several rotations of the galaxy, so they only last a billion years or so as a recognisable entity, whereas a globular cluster is usually the same age as the parent galaxy – in our case around 13 billion years old.

Ptolemy's Cluster on the 15/10/19 at 9:00 pm. Image Credit: Stellarium Ptolemy's Cluster. Image Credit & Copyright: Rolf Wahl Olsen
The Sculptor Galaxy:

The Sculptor or the Silver Coin Galaxy (NGC253) is a barred galaxy in the Sculptor constellation roughly 67,000 light years in width. It was discovered by Caroline Herschel in 1783, whilst carrying out a comet search. It is one of the Sculptor group of galaxies, which is grouped around the south galactic pole (These galaxies are sometimes named “The South Polar Group”). The Sculptor group may be the next closest group of galaxies beyond our Local Group, located about 11.5 million light-years from Earth.

Often called a Starburst galaxy because it has a large number of stellar nurseries in which many hot young blue stars are being formed. This is due as a result of a collision with a dwarf galaxy approximately 200 million years ago. The process of star formation and subsequent explosion as supernovae occurs at an unusually high rate of star birth.

These young stars emit radiation that causes the hydrogen gas to glow brightly in pink. NGC253 has many Wolf Rayet stars (WR stars start off as hot massive stars, around x20 solar masses, that rapidly lose mass by blowing their hydrogen envelope away in the form of high-velocity stellar winds.) The Silver Coin Galaxy also has a large proportion of dust, although not in clearly defined lanes, such as those found in the Milky Way Galaxy.

With an apparent magnitude of 7.2, it’s the second easiest galaxy to see after Andromeda and not including the Milky Way’s two satellite galaxies (The Large and Small Magellanic Clouds). With good viewing conditions, it can be seen with binoculars with a long axis ~2/3 of the full moon.

Sculptor Galaxy on the 15/10/19 at 9:00 pm. Image Credit: Stellarium Sculptor Galaxy - Image Credit & Copyright: Mike O'Day
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 a 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 15/10/19 at 9:00 pm. Image Credit: Stellarium Albireo. Image Credit: Palomar Observatory/STScI/WikiSky
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’. 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 are 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 15/10/19 at 9:00 pm. Image Credit: Stellarium 47 Tucanae. Image Credit & Copyright: Mike O'Day

Phases of The Moon:

October 2019 Moon phases

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