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Ephemeris: 09/23/2025 – Neptune is at opposition today

September 23, 2025 Comments off

This is Ephemeris for Tuesday, September 23rd. Today the Sun will be up for 12 hours and 6 minutes, setting at 7:37, and it will rise tomorrow at 7:32. The Moon, 2 days past new, will set at 8:07 this evening.

I normally don’t talk about observing things in the sky unless it can be seen with the naked eye, or can be seen in binoculars which are near stars that are visible to the naked eye. So I rarely talk about the planet Neptune. The last time was eight years ago and for the same reason as today. Neptune is in opposition with the Sun. That is, it is exactly opposite to the Sun in the sky, rising at sunset and setting at sunrise. Not only that, today is the 179th anniversary of the date it was discovered in 1846. Interestingly, it was first seen by Galileo. In one of his drawings of Jupiter and its moons that he made with his small telescope, there happened to be a background star that he recorded. That star turned out to be Neptune.

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

Naptune as seen from Voyager 2 and the James Webb Space Telwescope.
Neptune as seen from Voyager 2 and the James Webb Space Telescope. The Voyager image is on the left . The reason the images appear so different is that the Voyager image was taken in visible light while the James Webb image is in the infrared. It allows the detector to pick up Neptune’s faint rings, features and moons more easily. Neptune is 30 times the Earth’s distance from the Sun, and it takes 165 years to orbit the Sun. Credit NASA/JPL.

Categories: Anniversary, Ephemeris Program, Infrared Astronomy, Planets Tags: