October

New Zealand switched to summer time, that is we put our clocks forward one hour. We are seriously starting to think now about solar astronomy. As the fishhook of Maui sinks towards the western horizon, and with it the galactic centre, there are still many wonderful objects to see in the night sky. Just after sunset, all the deep sky objects from Scorpius and Sagittarius are on the western part of the sky. The Small Magellanic Cloud is good to observe after sunset. 

Grus, the Crane – famous constellation with double doubles is getting close to the Zenith this month, the Sun is in Virgo until November the 1st and Pisces lay on the horizon at sunset. 

A bit about October

October, as the name says it, (from the Greek ôctō meaning “eight”) is the eighth month in the old calendar of Romulus c. 750 bc. This was a lunar calendar, which had 10 months, the year starting with March. Each month had 30 or 31 days and there was a period of “winter”, which consisted of approximately 50 days. October retained its name after January and February were inserted into the original Roman calendar. 

The original calendar, believed to be created by early kings Romulus and Numa Pompilius, was probably an observational lunar calendar. The first day was a kalenda, from which the name calendar derives and it signified the start of a new lunar phase, probably the new crescent Moon. The Romans also had the nones – which literally meant the ninth day before the ides, which were the days in the middle of the month, and were determined by the Full Moon. So for example, the ides of March was initially the first Full Moon of March.

What’s the Sun up to?

In reality, the Sun does not spend an equal amount of time passing through the zodiacal constellations, for the simple reason that these constellations are different areas – patches in the sky. So technically, this month, the Sun is in Virgo where it will stay until the 1st of November, when it moves into Libra. The Sun has been in Virgo since the 17th of September. Virgo is a really long constellation to transit. 

The zodiacal constellation Virgo. The path of the Sun is marked by the yellow line. Image created with Carte du Ciel.

What’s at Zenith?

Beautiful Sagittarius is at Zenith just after Sunset and then as the month progresses it’s replaced by other amazing constellations such as Microscopium, which is basically a rectangle, and then one of our favourite constellations, Grus towards the middle of the month – or later on in the evening, whichever you prefer. The cool thing about Grus, the Crane is that it has many double stars, it almost looks like a curved line, which is the imaginary tail that points us towards the Small Magellanic Cloud, which is in the neighbouring constellation, another bird, the Toucan. 

In addition to that, another favourite of mine, Fomalhaut, is getting very close to Zenith this time of the year. I love Fomalhaut because when I was in the Northern Hemisphere, before I travelled here, it was the southernmost star that I could see, and it was said to show the passage south. It actually does if you know where to look. Fomalhaut is one of the Royal stars, along with Antares, Regulus and Aldebaran. 

The Royal stars were the guardians of the sky in approximately 3000 BCE during the time of the Ancient Persians in the area of modern-day Iran. The Persians believed that the sky was divided into four districts with each district being guarded by one of the four Royal Stars. The stars were believed to hold both good and evil power and the Persians looked upon them for guidance in scientific calculations of the sky, such as the calendar and lunar/solar cycles, and for predictions about the future.

The Milky Way, Scorpius and Orion 

The bulk of the Milky Way is on the Western horizon. The Galactic centre slowly going down sinking behind the Sun. The Southern Cross, which is also visually in the Milky Way, is doing its big descent as it dives towards the horizon, getting lower and lower each evening throughout the month, as seen after sunset. It is circumpolar so it never disappears from the Southern Sky but it means the lovely clusters and nebulae that you would have enjoyed in Spring and Winter have long gone from being in a favourable viewing position — they now compete with the horizon.

The Western horizon from Wellington, October 15, 2019 at 21:00. Image created with Stellarium

The other patch of the Milky Way that remains in a very good position for viewing is the area around Sagittarius and Scorpius with many globular clusters and nebulae (distant, celestial clouds) to look at. The highlights, for me, are the bright nebulae such M16 (the Eagle Nebula), Lagoon Nebula and the very photogenic Trifid Nebula. Ptolemy’s Cluster is a great naked eye object that is visible between the two constellations.

South Circumpolar Zone

Just after sunset, the Large Magellanic Cloud  and the Southern Cross are close to the horizon where the Small Magellanic Cloud is in a good position to observe. 

The Southern Horizon from Wellington, 15 October 21:00 h, image created with Stellarium.

What’s in the night sky in October 2019