September 22 marks the autumn equinox, signifying the astronomical beginning of autumn, where day and night are nearly equal in duration. The meteorological onset of autumn occurs earlier, on September 1, and by this time, the cooler temperatures and changes in nature are already evident.
This period offers excellent opportunities for sky observation, as the nights are longer but not yet as cold as winter.
The moon in September:
September 3 – New Moon
September 11 – First Quarter
September 18 – Full Moon
September 24 – Last Quarter
The planets in September:
The planet Venus remains visible in the western sky at dusk as an evening star, although its duration of visibility will slightly increase. On September 5, a very narrow waxing crescent moon will align with Venus.
Mars is still primarily visible in the latter half of the night in August and is growing brighter. However, it remains too distant for us to observe surface details through a telescope.
Jupiter rises earlier as the month progresses, making its appearance at 11:45 p.m. at the beginning of September and by 10:00 p.m. at the end of the month. It significantly increases in brightness, becoming the brightest planet visible in the night sky, as Venus sets before Jupiter rises. Jupiter will pass near the crescent moon during the night of September 23-24.
Saturn, the ringed planet, is visible in the sky all night long. On September 17, the full moon will coincide with Saturn.
The starry sky in September:
As darkness falls, the Summer Triangle comprised of Deneb, Vega, and Altair rises high in the sky. With advancing night, the band of the Milky Way becomes increasingly discernible directly to the south, stretching in a high arc from horizon to horizon across the sky.
However, viewing the Milky Way requires good visibility conditions. Light pollution or bright moonlight can significantly hinder the sighting of the Milky Way.
In rural areas, devoid of artificial lighting, observing the Milky Way can be a breathtaking experience.
The visible band of the Milky Way consists of countless stars, star clusters, and nebulae that form part of our galaxy and that we can observe from Earth’s perspective.
Only about a century ago, astronomers believed our sun was close to or at the center of our galaxy.
It has since been discovered that the Milky Way is much larger than previously thought, comprising a disk-shaped structure roughly 100,000 light years in diameter, with vast spiral arms. Our sun is situated at the edge of the galaxy within one of these spiral arms and orbits with other stars around the Milky Way’s center, a journey that takes approximately 200 million Earth years.
The Milky Way contains around 200 billion stars, with the total estimated number of stellar objects, including white dwarfs, neutron stars, and black holes, around 400 billion.
Cover photo: Photo of the Milky Way by Hermann Koberger
The Astronomical Spectacle of September: Equinox, Moon Phases, and Celestial Events
September 22 marks the autumn equinox, which signifies the astronomical beginning of autumn. On this day, day and night are approximately equal in length. In contrast, the meteorological start of autumn occurs earlier, on September 1, when we can already feel the season’s change through cooler temperatures and changes in nature. This transitional period offers fantastic opportunities for sky observation, as the nights grow longer and remain relatively mild compared to the cold winter months.
The Moon’s Journey in September
The moon plays a significant role in the night sky throughout September. Here’s a breakdown of the key phases:
| Date | Phase |
|---|---|
| September 3 | New Moon |
| September 11 | First Quarter |
| September 18 | Full Moon |
| September 24 | Last Quarter |
Planets to Observe This Month
This month is particularly exciting for planet watchers, with several celestial bodies prominent in the night sky:
- Venus: This dazzling evening star can be seen in the western sky at dusk. On September 5, a narrow waxing crescent moon will align with Venus, creating a beautiful sight.
- Mars: Visible primarily in the second half of the night, Mars is getting brighter as it moves closer to Earth. However, it is still too distant for detailed telescope observations.
- Jupiter: Rising earlier each night (at 11:45 p.m. at the start of September and by 10:00 p.m. by the month’s end), Jupiter is set to become the brightest planet in our night sky, even passing the crescent moon on the night of September 23-24.
- Saturn: This iconic ringed planet is visible all night long, and on September 17, it will share the spotlight with the full moon.
Exploring the Starry Sky: The Milky Way and Beyond
As the sun sets, the Summer Triangle, featuring stars Deneb, Vega, and Altair, becomes prominent. With increasing darkness, the breathtaking band of the Milky Way becomes visible directly to the south, arching gracefully across the sky. Observing the Milky Way requires optimal conditions, as light pollution and bright moonlight can immensely hinder visibility. In rural areas, where artificial lighting is minimal, the experience of stargazing can be truly awe-inspiring.
Observing the Milky Way reveals countless stars, star clusters, and nebulae belonging to our galaxy. Notably, only about a century ago, astronomers thought our Sun was at or near the center of the Milky Way. This misconception has since been corrected, revealing that our galaxy is far vaster than previously imagined. The Milky Way is shaped like a disk about 100,000 light-years in diameter and is adorned with massive spiral arms. Our Sun resides at the galaxy’s edge and completes a rotation around the center approximately every 200 million years. Today, we estimate that the Milky Way comprises about 200 billion stars, with total stellar objects—including white dwarfs, neutron stars, and black holes—amounting to around 400 billion.
Benefits of Sky Observation
Engaging in sky observation during September offers numerous benefits:
- Connection to Nature: Observing celestial events allows us to connect with nature on a deeper level, providing a sense of awe and appreciation for the universe.
- Stargazing as a Hobby: Astronomy can be an enriching hobby that encourages curiosity and exploration, leading to thrilling discoveries and knowledge.
- Educational Value: Observing planets, stars, and celestial events can enhance your understanding of astronomy and inspire future generations of scientists.
Practical Tips for Moon and Planet Observation
To make the most of your astronomical experience this September, keep the following tips in mind:
- Find a Dark Spot: Seek locations away from city lights to enhance visibility and enjoy the beauty of the night sky.
- Use Binoculars or a Telescope: If you have access to binoculars or a telescope, they can significantly enhance your viewing experience, especially for planets like Saturn and Jupiter.
- Dress Warmly: Nights can become chilly as autumn progresses, so dress in layers to ensure comfort during stargazing.
- Learn About the Constellations: Familiarize yourself with the constellations that are visible during this season, as recognizing stars and patterns can deepen your appreciation.
First-Hand Experience: Stargazing Events
Participating in local astronomy clubs or events can provide an enriched experience. For instance, many clubs host stargazing nights where enthusiasts gather to observe celestial phenomena through telescopes and share knowledge. These communal observations can foster a sense of camaraderie and inspire conversations about the mysteries of the universe.