Astronomy Essentials

Visible planets and night sky for September

September 23: Equinox

The September equinox – when the sun crosses the celestial equator, moving from north to south – happens at 6:50 UTC (1:50 a.m. CDT) on September 23. This equinox brings autumn to the Northern Hemisphere, and spring to the Southern Hemisphere. Read about the 2023 September equinox, or watch the video below.

September 23 evening: Moon near Teapot

The moon reached first quarter last night. Now it’s a slightly thicker, waxing gibbous. At sunset, the moon will be in the south, and as the sky darkens, the stars of the Teapot – an asterism in the constellation Sagittarius the Archer – will appear in front of the lit side of the moon. The Teapot marks the direction to the center of our Milky Way galaxy.

Chart via EarthSky.

Comet Nishimura, now in the evening sky

Comet C/2023 P1 (Nishimura) has now moved from the morning sky to the evening sky. Early sightings were promising, but we haven’t heard much about it lately, or seen many photos. The comet is in bright twilight! Read more about Comet Nishimura.

EarthSky Minute for September 18-24

Late September, into early October: Venus and Mercury

Venus reaches greatest brilliancy on September 19. And Mercury – near its September 22 greatest elongation – will be nearby. The video below has more.

September and October: Watch for the zodiacal light

The weeks around the September equinox are the best time to see a hazy pyramid of light in the sunrise (Northern Hemisphere) or sunset (Southern Hemisphere) direction. Watch for this light – called the zodiacal light – before dawn breaks, or when all traces of evening twilight have left the sky. Read more here, or watch the video below.

September 24 and 25 evenings: Moon visits Capricornus

The bright waxing gibbous moon will pass in front of the constellation Capricornus the Sea-goat on the evenings of September 24 and 25. Notice that Capricornus has the shape of an arrowhead.

Chart via EarthSky.

September 26 and 27 evenings: Moon visits Saturn

The bright waxing gibbous moon will sweep past the planet Saturn on the evenings of of September 26 and 27. You need a telescope to see Saturn’s rings, but you might notice that the planet shines with a steady light and golden color.

Chart via EarthSky.

September 28 and 29, all night: Super Harvest Moon

The instant of September’s full moon – the last of four full supermoons of 2023 – falls at 9:57 UTC (4:57 a.m. CDT) on on September 29. For us in North America, the night of September 28-29 is our best for full-moon watching. But – as the closest full moon to the equinox – September 2023’s full moon also carries the name Harvest Moon. And the Harvest Moon is characterized by appearing full, or almost full – and by rising around the time of sunset for us in the Northern Hemisphere – for several nights following full moon. Read about the Harvest Moon.

Chart via EarthSky.

September 29 and 30: Super Harvest Moon and Jupiter

The crest of the moon’s full phase falls early in the day on September 29. So – on the evening of September 29 – a bright full moon will rise soon after sunset, followed a little later by the bright planet Jupiter. Then on the evening of September 30, the waning gibbous moon will rise shortly after sunset, too. Why shortly after sunset when it’ll be after full moon? Because this was the Harvest Moon, which is characterized by appearing full, or almost full – and by rising around the time of sunset for us in the Northern Hemisphere – for several nights following full moon. On the nights of September 29 and 30, watch the Harvest Moon and Jupiter travel across the sky all night, until dawn. Read about the Harvest Moon.

Chart via EarthSky.

Heads up! 2 great American eclipses coming

The first of two great American solar eclipses will take place on Saturday, October 14, 2023. Only those using proper eye protection – in a narrow swath sweeping over North and South America – will get to see the sun form a ring around the moon at mid-eclipse. But many more will observe a partial solar eclipse. Make sure you protect your eyes with eclipse glasses throughout this eclipse. Order them now!

Planets in September

Mid-September mornings: Venus and Mercury

Around now, for viewers in the Northern Hemisphere, Venus will climb higher each morning and will reach its greatest elongation on October 23, 2023. And Mercury will rise in the east shortly before sunrise. It will lie in the bright morning twilight near the similarly bright star Regulus and far below brilliant Venus. Mercury will brighten from magnitude -0.3 to -1.0 during the month. This is the best morning apparition for Mercury in 2023 for the Northern Hemisphere. Around greatest elongation, on September 22, Mercury rises about an hour before sunrise.

Chart via EarthSky.

September mornings: Venus

After passing between the sun and Earth on August 13, 2023, brilliant Venus is up in the September dawn sky before sunrise. Venus will be brightest in the morning sky around September 19, 2023, and will reach 44 degrees elongation from the sun by the end of the month. Venus will brighten from magnitude -4.6 to -4.8 during the month. It’ll reach greatest elongation from the sun next month. The bright star Procyon of Canis Minor the Lesser Dog shines nearby. Venus will rise about 2 hours before sunrise at the beginning of the month and about 3.5 hours before by month’s end. The planet Mercury may be visible below Venus and near the horizon.

Chart via EarthSky.

September overnight: Jupiter

Jupiter is in the constellation of Aries the Ram during the month of September. It will shine near the pretty Pleiades star cluster. Jupiter will brighten from magnitude -2.5 to -2.7 during the month. Jupiter will rise about 10 p.m. (your local time) at the beginning of the month and will rise around 8 p.m. by month’s end. It’s high in the sky at dawn.

Chart via EarthSky.

September all night: Saturn

Saturn will lie in the southeast after sunset during September. It will be near the dim “Water Jar” asterism of Aquarius the Water Bearer. Saturn reached opposition on August 27, 2023, so it will remain well placed for observing this month. Saturn will shine at magnitude 0.5 during the month. The full Harvest Moon supermoon will visit Saturn on September 28, 2023. Saturn will rise and set with the sun at the beginning of the month and will rise before sunset and set about 3 hours before sunrise by month’s end.

Chart via EarthSky.

Thank you to all who submit images to EarthSky Community Photos! View community photos here. We love you all. Submit your photo here.

Looking for a dark sky? Check out EarthSky’s Best Places to Stargaze.

Sky dome maps for visible planets and night sky

The sky dome maps come from master astronomy chart-maker Guy Ottewell. You’ll find charts like these for every month of 2023 in his Astronomical Calendar.

Guy Ottewell explains sky dome maps

View larger. | Here is the sky dome view for September 2023. It shows what is above the horizon at mid-evening for mid-northern latitudes. The view may vary depending on your location. Image via Guy Ottewell. Used with permission.

Heliocentric solar system planets

The sun-centered charts come from Guy Ottewell. You’ll find charts like these for every month of 2023 in his Astronomical Calendar.

Guy Ottewell explains heliocentric charts.

View larger. | Heliocentric view of solar system, September 2023. Chart via Guy Ottewell.

Some resources to enjoy

For more videos of great night sky events, visit EarthSky’s YouTube page.

Watch EarthSky’s video about Two Great Solar Eclipses Coming Up

Don’t miss anything. Subscribe to daily emails from EarthSky. It’s free!

Visit EarthSky’s Best Places to Stargaze to find a dark-sky location near you.

Post your own night sky photos at EarthSky Community Photos.

Translate Universal Time (UTC) to your time.

See the indispensable Observer’s Handbook, from the Royal Astronomical Society of Canada.

Visit for precise views from your location.

Almanac: Bright Planets (rise and set times for your location).

Visit TheSkyLive for precise views from your location.

Great resource and beautiful wall chart: Guy Ottewell’s zodiac wavy chart.

Amateur astronomers are buzzing! Guy Ottewell is offering his beloved Astronomical Calendar for 2023 in both electronic and printed versions.
Guy Ottewell’s Zodiac Wavy Chart is a 2-by-3 foot (0.6 by 0.9 meter) poster displaying the movements of the sun, moon and planets throughout the year. You can purchase it here. Image via Guy Ottewell. Used with permission.

Bottom line: In September 2023, Mars is going into the sun. Jupiter and Saturn are evening objects. Morning planets are Venus and Jupiter, with Mercury low on the eastern horizon. Visible planets, here.

September 23, 2023
Astronomy Essentials

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