What’s In September’s Skies

By Matt Woods

Planets:

This month we will lose Mercury to the Sun’s glare in the early evening in the middle of September. Venus too will disappear into the Sun’s glare in the second week of the month in the early morning. Mars can be found in the constellation Taurus (The Bull), and it will pass close to the Red Giant star Aldebaran (The red eye of Taurus) at the end of the first week of September. It should be a nice view, with Taurus appearing to have two red eyes.

Jupiter it can be found in between the constellation of Cetus (The Sea Monster) and the constellation of Pisces (The Fish) in the evening sky. On the 27th of September at 02:00 am (AWST), Jupiter will reach opposition and will be at its best to look at. Saturn can also be found in the evening sky in the constellation of Capricornus (The Sea-Goat). Uranus is rising in the early morning in between the constellation of Aries (The Ram) and the constellation of Taurus. Neptune again is just up from Jupiter in between the constellation of Pisces and the constellation of Cetus. On the 10th of September at 05:00 am (AWST), Neptune will reach opposition. Even though it’s the best time to see Neptune it’ll still will look like a blue dot.

Mars, Jupiter, Saturn, Uranus, and Neptune on the 16/09/22 at 3:00 am (AWST)

Astronomical Events:

Zodiacal Light Season Begin:

Equinox on the 22nd of September causes the backscattering of light from dust particles spread out along the ecliptic plane (The apparent path of the Sun’s motion on the celestial sphere as seen from Earth). Spring and Autumn are the best times to see this pearly glow in the dawn or dusk. This is due to the steep angle of the ecliptic relative to our horizon. The September Equinox season favours dusk for the Southern Hemisphere, and dawn for the Northern Hemisphere; and the reverse is true near the March equinox.

To see the zodiacal light, go out around an hour after sunset or an hour before dawn, and look from as darker a site as possible. Any light pollution or faint glow from distant cities on the horizon will destroy the ethereal glow. The zodiacal light will appear as a slender pyramidshaped glow, tracing the length of the ecliptic plane.

Zodiacal Light in front of the Milky Way

The September Equinox:

On Friday the 23rd of September, The Southward Equinox occurs at 09:03 am (AWST), marking the beginning of astronomical Fall for the Northern Hemisphere, and the start of Spring for the Southern Hemisphere. This is an exact moment when the Sun’s declination equals 0 as seen from the Earth. The two points where the ecliptic or the imaginary path the Sun seem to trace out along the celestial sphere meets the celestial equator are known as the equinoctial points. In the 21st century, the September Equinox will fall on the 22nd or the 23rd until 2092, when it will begin falling on September 21st every fourth year.

The Equinox (literally meaning ’equal nights’ in Latin) means that night and day are nearly equal worldwide, and that the Sun rises due east of an observer on the equinox and sets due west. The Full Moon nearest to the September Equinox is known as the Harvest Moon, a time when farmers use the extra illumination at dusk to bring in crops. In 2022, the Harvest Moon falls on September 10th.

The term Equilux is sometimes used to discern the difference between the true Equinox and the point when sunlight length equals the length of the night. Several factors play a role in this, including the time it takes the physical diameter of the Sun to clear the horizon, atmospheric refraction, and the observer’s true position in their respective time zone. The Equilux occurs within a few days of either Equinox.

Celestial Wonder To Look At This Month:

The Pegasus Globular Cluster:

The Pegasus Globular Cluster (M15 & NGC 7078) is a globular cluster and it’s about 35,700 lightyears from Earth in the constellation Pegasus. It was discovered by Jean-Dominique Maraldi in 1746 and is estimated to be between 12.5 billion years old, which makes it one of the oldest known

globular clusters. It’s 175 light-years in diameter and is one of the most densely packed globular clusters known in the Milky Way galaxy. Its core has undergone a contraction known as “corecollapse” and it has a central density cusp with an enormous number of stars surrounding what may be a central black hole.

The Pegasus Cluster is home to over 100,000 stars, and the cluster is notable for containing many variable stars and pulsars, including one double neutron star system. It also contains the first planetary nebula discovered within a globular cluster in 1928. Just three others have been found in globular clusters since then. It can be observed with binoculars or a small telescope, appearing as a fuzzy star. Telescopes with a larger aperture (at least 6”) will start to reveal individual stars.

The Pegasus Globular Cluster on the 15/09/22 at 9 pm

Messier 15

The Pegasus Globular Cluster

Image Credit: ESA/Hubble & NASA