The Visible Planets
Mercury is found about 10° above the eastern horizon before sunrise at the start of the month. On September 1, look for the shallow waning crescent Moon near Mercury. As the month progresses, Mercury slips lower toward the eastern horizon, only to disappear in the Sun’s sunrise glow by the end of the month. Mercury is at its greatest elongation west (18°) of the Sun on September 4.
Venus begins to be seen low above the west-southwest horizon after sunset early in the month. While the angular distance between Venus and the Sun increases during the month, the shallow arc of the ecliptic from our northern latitude keeps Venus within the sunset glow for the month and at its low position in the west-southwestern sky. See if you can spot the thin waxing crescent Moon to the lower left of Venus after sunset on September 5.
Mars can be seen rising along the northeastern horizon around midnight local time. It starts the month in the constellation of Taurus, the bull, but quickly moves into the adjacent zodiac constellation of Gemini, the twins, around September 5 and remains in that constellation all month long. Look for Mars just to the east of the much brighter planet Jupiter through the month. On September 25, look for Mars just below the waning crescent Moon through the night.
Jupiter rises along the northeast horizon at around 11:00 p.m. at the start of the month and by 10:00 p.m. at the end of the month. It is located within the constellation of Taurus, the bull, where it stays all year long. Look for the red planet Mars just to the east of Jupiter. The red eye of the bull, the star Aldebaran, can be seen to the lower right of Jupiter. Look for the waning gibbous Moon near Jupiter on the nights of September 23 and 24.
Saturn is seen rising along the east-southeastern horizon at sunset, traversing the southern sky through the night, and then setting along the southwestern horizon by the time of sunrise. Saturn is at its point of opposition on September 7 and will provide excellent telescopic views all night long through the month. It is seen as the brightest object amongst the stars of Aquarius, the water bearer. On the evening of September 16, look for Saturn near the waxing gibbous Moon.
Moon Phases
September 2 New Moon
September 11 First Quarter Moon
September 17 Full Moon (The Harvest Moon or Corn Moon) Shallow partial lunar eclipse
September 24 Last Quarter Moon
Special Events
International Space Station (ISS) Observable Passes
During the month of September there will be several favourable passes of the ISS. From September 1 to September 9, observable passes of the ISS will be found in our predawn morning sky. From September 10 to September 29, more favourable early evening passes will be seen between 7:00 p.m. and 11:00 p.m. Exact times of these passages for your location can be found by visiting the website http://www.heavens-above.com or by using satellite tracking smart phone apps like Sputnik or Spot-the-Station.
September ? JAXA’s Martian Moon eXploration mission launch (to Phobos and Deimos)
September 7 Saturn at opposition (72-light minutes away)
September 9 Royal Astronomical Society of Canada (RASC) Edmonton Centre meeting
Live in the Zeidler Dome at TWOSE and presented virtually through Zoom.
7:30 p.m. – 9:30 pm
Free for anyone to attend.
See http://www.edmontonrasc.com for more details.
September 14 International Observe the Moon Night
September 17 Partial Lunar Eclipse
Partial Umbral Eclipse Begins: 8:12 p.m.
Mid-Umbral Eclipse: 8:45 p.m.
Partial Umbral Eclipse Ends: 9:16 p.m.
September 24 to 29 Northern Prairie Star Party 2024
Black Nugget Lake, AB
See https://edmontonrasc.com/northern-prairie-star-party/ for details.
September 22 Fall equinox occurs at exactly 6:44 a.m. MDT
September 25 to October 5 Comet Tsuchinshan-ATLAS C/2023 A3 may become visible in our eastern predawn sky! Comets are notoriously unpredictable in what they do, however it might become bright enough to see with the unaided eyes before sunrise during this time. Stay tuned for developments!
