The Night Sky This Month: September 2022

Photo by Greg Rakozy

This year, the September Equinox occurs at 00:55 UTC on September 23rd. On this date, the amounts of light and darkness will be almost equal across the world, which marks the autumnal equinox in the northern hemisphere and the vernal equinox in the southern hemisphere.

Planetary observers should note that the planet Neptune reaches a point of opposition on September 16th. On this date, Neptune will be at its closest approach to Earth, and as a result, it will be brighter on the 16th than on any other night this year. The planet will also be visible throughout the night for most of September, but despite its favorable location and high brightness, it might be difficult to spot the planet unless you have access to a 20-inch or larger telescope.

The Moon Phases in September 2022

New Moon First Quarter Third Quarter Full Moon
September 3rd September 10th September 17th September 25th

The Planets in September 2022

Note that the elevations of planets given here are as viewed from about latitude 250N. Therefore, observers north of latitude 250N will see the planets at progressively lower elevations the further north of latitude 250N they are located. Nonetheless, below are some details of what to expect in terms of the planet’s visibility throughout the month of September-

– Mercury will remain within about 12 degrees of the Sun throughout the month, and will therefore not be visible since it will reach its highest elevations during daylight hours.

Venus is now approaching the Sun, but it will nevertheless be visible in the pre-dawn sky from around 05:56 (EDT) at the start of the month. The planet will then reach an elevation of only 9 degrees above the eastern horizon, and will become lost in the Sun’s glare at around 06:44 (EDT). By month’s end, Venus will be within about 6 degrees of the Sun, and will therefore not be accessible.

Mars is still visible as an early morning object, and as seen from latitude 250N, the Red planet will become accessible about 15 minutes after midnight as the month starts. The planet will rise progressively earlier as the month wears on, but it will reach an elevation of 82 degrees above the southeastern horizon at the beginning of September, which will increase slightly to 86 degrees above the southern horizon at the end of the month.

Jupiter is now approaching a point of opposition and is visible throughout most of the night during September. At the start of the month, Jupiter will rise at about 21:38 (EDT), but it will rise progressively earlier as the month wears on. By September’s end, Jupiter will rise at about 19:34 (EDT) and it will remain visible until about 06:22 (EDT). Note also that Jupiter will rise to between 63 degrees and 65 degrees above the eastern horizon throughout the month.

Saturn, like Jupiter, is also approaching a point of opposition, and starts the month rising at about 20:05 (EDT) in the southeast, to rise to an elevation of 48 degrees above the southern horizon just after midnight. By month’s end, the planet will rise at 19:34 (EDT) in the southeast to reach an elevation of 47 degrees above the southern horizon before sinking to below 10 degrees above the southwestern horizon at about 02:44 (EDT).

Meteor Showers in September 2022

No significant meteor activity is expected to occur during September, apart from the normal background activity at this time of the year.

Deep Sky Objects to Look for in September 2022

Globular star clusters are among the most spectacular objects in the sky, and several of the brightest globular clusters in the northern sky are now becoming accessible to observers with modest observing equipment. Below are some details of two globular clusters that are always well-worth hunting down.

Messier 13 (M13, NGC 6205, Hercules Globular Cluster)

Located about 22,000 light-years away in the constellation Hercules,  this magnitude 5.8 cluster consists of several hundred thousand stars, which makes this cluster one of the largest and most massive of the Milky Way’s globular clusters.

Although the Great Hercules Cluster (M13) has an effective diameter of just over 145 light years, M31’s most noteworthy feature is that its stellar density is at least one hundred times higher than the stellar density in the Sun’s immediate vicinity. As a result, collisions and mergers between stars in the cluster are inevitable, which accounts for the relatively high number of “blue stragglers” in the cluster.

Note that the cluster appears as a bright, round patch of light in binoculars, but a 4-inch telescope on low power will resolve individual stars in the cluster’s outer regions.

Messier 92 (M92, NGC 6341)

Located about 26,700 light years away, M92 is another of the great globular clusters in Hercules, and one of the brightest globular clusters in the northern sky. The cluster is, in fact, visible without optical aid under good seeing conditions from dark sites.

One notable fact about M92 is that Earth’s North Celestial Pole passed within one degree of the cluster about 12,000 years ago, and will do so again in about 14,000 years, which will then place the cluster closer to the North Celestial Pole than Polaris (the current North Star) is now.

M92 is visible in small telescopes even from severely light-polluted sites as a patch of light, but from dark sites, even 2-inch telescopes will easily resolve individual stars in the cluster’s outer fringes.

Messier 31 (M31, NGC 224, Andromeda Nebula)

Located about 2.5 million light years away in the constellation Andromeda, our closest large neighbor in the Local Group of galaxies has been the subject of intense study in recent years in efforts to gauge its mass more accurately.

It had long been thought that M31 was at least 25% more massive than the Milky Way, but recent research suggests that the Milky Way might actually be marginally more massive than M31, although M31 is now confirmed to be the largest member of the Local Group- even if the halo of stars around the galaxy is excluded.

As a point of interest, the diffuse halos of stars around both M31 and the Milky Way extend outwards by between 1 million and 2 million light years, which means that the outer fringes of both galaxies are already being perturbed by an intense gravitational interaction. Therefore, the great collision between the two largest and most massive members of the Local Group has already begun.

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