September Night Sky
Sky events for this month & objects for observation can be found here.
Click to enlarge. A larger printable version of this chart can also be found here.
PLANETS FOR SEPTEMBER
In the chart above for mid-month, the colored arrows show the motion of each planet and the Sun during the month. The Moon is plotted for the evening dates in the Americas when it's waxing (right side Illuminated and the visible surface of the moon increases) or full, and for the morning dates when it's waning (left side illuminated visible surface of the moon decreases). Right Ascension and Declination are the equivalent of longitude and latitude of celestial objects. The Ecliptic is the line followed by the Sun in the sky throughout the year. Note that most of the planets and the Moon are also located close to this plane. The Local Time of Transit indicates when the area of sky passes the meridian line from directly south to north. Sky & Telescope.
PLANET SIZES & ILLUMINATION
Using a telescope one can observe Jupiter's cloud belts and moons and Saturn with its magnificent ring system; both are are well placed for observing in the eastern evening sky. Jupiter will reach "opposition" and be closest to the Earth – and therefore its largest and brightest – on September 26. Mars is getting larger and now will show some detail on its surface, with closest approach (opposition) taking place in December. Neptune reaches opposition on September 16. Even so, both it and Uranus remain very far away and have relatively small discs, and generally reveal little of any detail.
Graphics - Sky & Telescope
THE SUN HAS AWAKENED!
Solar activity continues to increase with the Sun's 11 year solar cycle progressing and providing increased numbers of sunspots, flares, and geomagnetic storm activity. Solar Cycle 24 ended a little earlier than predicted in late 2019, and Cycle 25 is now predicted to peak in late 2024, and currently looks to have a sigificantly greater number of sunspots than Cycle 24.
Solar activity near the peak of Solar Cycle 24. Images - Bob Yoesle
Solar activity is increasing as we get further into the solar cycle. And while days are now getting shorter, there remain many hours of daylight in which to do solar observation. Telescopes equipped with approved solar filters are a safe way to see sunspots and other solar activity.
The September Autumnal Equinox occurs at 6:04 pm PDT on September 22, and marks where the center of the Sun crosses directly above the equator moving southward in the sky. Due to this the length of day and night are very similar, and almost exactly equal on September 22, which marks the first day of fall in the northern hemisphere, and the first day of spring in the southern hemisphere.
Following the September equinox, the Sun is moving further southward in the sky along the ecliptic toward the northern hemisphere Winter solstice, and the days are increasingly shorter and the nights longer.
The Earth's orbit around the Sun is not a perfect circle, but rather a slightly elongated ellipse. The distance to the Sun has little effect on the actual seasons in either hemisphere. The difference is relatively small and not enough to overcome the much greater effect of the Earth's axial tilt which results in the seasons.
This months Full Moon is known as the Harvest Moon or the Corn Moon depending on which Full Moon (Sept or Oct) is closest to the Fall Equinox. Its brightness traditionally helped extend the day for the harvesting of grain and other crops. Nights around the New Moon are best for viewing the stars and nebulae in night sky. This month's New Moon falls on September 25th.
In Greek mythology, fall has historically been represented by Carpo, the goddess of autumn, the time of ripening and harvests. She was one of the Horae ("hours") of the traditional seasons, daughters of Zeus and Aphrodite.