This is Ephemeris for Wednesday, September 17th. Today the Sun will be up for 12 hours and 24 minutes, setting at 7:49, and it will rise tomorrow at 7:25. The Moon, 3 days past last quarter, will rise at 3:44 tomorrow morning.
Let’s take our weekly look at the whereabouts of the naked-eye planets. Saturn now rises at 8:01 PM in the east. In a telescope Saturn sports a very thin ring, 2° from being edge on. Saturn has an axial tilt of about 27°, so it has seasons like the Earth and since its rings are over its equator, when they go edge on to the Sun, it is an equinox for it, which happened in May. Earth being close to the Sun and moving, see nearly the same thing. Now the ring angle for us will decrease to about a third of a degree by November 23rd before increasing. By 6 AM Jupiter will appear above the brighter Venus in the Eastern sky and among the stars of Gemini. Venus and Jupiter will have the waning crescent Moon between them tomorrow morning.
The astronomical event times given in this blog are for the Traverse City/Interlochen area of Michigan (Lat 44.7° N, Long 85.7° W; EDT, UT – 4 hours) unless stated otherwise. Times will be different for other locations.
Addendum
Saturn, low in the east, below and a bit right of the Great Square of Pegasus, which stand on one corner. Created using Stellarium.
Venus, the waning crescent Moon and Jupiter are visible in the east among the winter stars at 6:00 AM tomorrow morning, September 18, 2025. Saturn is low in the west. Created using Stellarium.
The waning crescent Moon with earth shine on the morning of September 18, 2025. Not much detail can be made out in binoculars otherwise.
Telescopic Saturn, Jupiter and Venus (north up) as they would be seen in a small telescope with the same magnification. On the evening of the September 17th 2025, Saturn will be 19.4″ in diameter, but its rings, even being nearly edge on, should show up brighter than seen here, and extend to 45.3″. They are tilted 2.0° from being edge on. On the morning of September 19th 2025, Jupiter will be 35.7″ in diameter. Europa is eclipsed by Jupiter, Io will begin its transit the face of Jupiter at 5:44 AM and will be nearly impossible to spot against the planet. Venus’ apparent diameter will be 11.5″, and be 88.8% illuminated. It’s on the far side of the Sun. The (”) symbol means seconds of arc, or 1/3600th of a degree. Created using Cartes du Ciel (Sky Charts), LibreOffice Draw and GIMP.
The naked-eye planets and the Moon at sunset and sunrise on a single night, starting with sunset on the right on September 17th, 2025. The night ends on the left with sunrise on the 18th. Click or tap on the image to enlarge it. Created using my LookingUp app and GIMP.
This is a low precision ephemeris of the Sun Moon and naked eye planet positions for today and tomorrow, September 17th and 18th, 2025. Some of the columns are self-explanatory, others are not. The transit column is the time that the body crosses the meridian and is due south. Elong, for elongation, is the angle between the Sun and that body. RA is right ascension, which is the object’s east-west position on the celestial sphere in hours and minutes. Dec is declination which is the north-south position of the object on the celestial sphere in degrees and minutes. R is the distance of that object from the Sun in astronomical units. An astronomical unit is about 93 million miles or 150 million kilometers. And Delta is the distance of that object from the Earth, also in astronomical units. I omit the ‘m’ in am and pm for compactness. The data was generated using my LookingUp for DOS app and displayed as a table by my Ephemeris Helper app.
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