Night Skies- September 2025

John and Peggy Hurley | Aug 28, 2025

All the planets are visible this month. Mercury and Venus are low in the ENE in morning twilight. Mercury will be lost before the month is out.  Jupiter will rise before 2 am and be high in the E by dawn. Saturn will rise in the E at dusk and set at dawn. Mars will be low in the W, setting during evening twilight.

Full Moon will be on the 7th and will be in eclipse for everyone but North and South America.  We also miss the partial Solar Eclipse two weeks later. (September 21). Saturn will be close to the Moon on Sept 8. The 14th is the last quarter Moon. Zodiacal Light might be visible in the East during the morning for two weeks. On the 16th Jupiter will be south of the Moon. Capella, Auriga’s brightest star, might be visible in the morning sky this week. Regulus, brightest star in Leo, Venus and the Moon will form a triangle in the early morning sky. Fall Equinox is on the 22nd and First Quarter Moon is on the 29th.

Last month, we printed that meteor showers were caused by debris from comets. This statement was called into question as recent discoveries have shown a meteor shower can be caused by an asteroid instead. Changes to equipment and software have led to many discoveries of things that don’t fit the old classifications. Discoveries from Asteroid Bennu and P/Comet Encke show a progression from one to the other.

Comets were easy to identify: they were in highly elliptical orbits around the sun and developed two tails as they approached the sun. Those tails were made from the plasma and particles the solar wind always pushed away from the sun. Asteroids were thought to be more like failed planets. We now know those are not necessarily true statements.

In 1993, Periodic Comet Shoemaker-Levy 9 was discovered in March and the repair for the Hubble Telescope’s astigmatism in December. When discovered S-L9 had been pulled into 21 pieces, each with some cometary tail. It was fittingly called ‘the string of pearls’.

The comet was not in orbit around the sun, though it used to be. It may have been pulled out of the solar orbit in the 1960s by Jupiter and was captured. That chunk of ice and rock got even closer in 1992 and in July of ’94 was going to crash into Jupiter!

Questions about the density of comets were topics of conversation. Now we know they are not like a sandbox and more like an icy slush ball kept in the freezer. The results of the impact on Jupiter was visible for months.

Fortunately, the repair of HST went better than hoped allowing everyone to watch the impacts happen. Learning to create a ‘fix’ for that astigmatism has allowed every telescope to counter for sky conditions if they want. While a backyard telescope has always been able to do ‘citizen science’, the choice is much larger now. More people are seeing fainter objects and it turns out, not all are easily classified. Comets and Asteroids were thought to be very different, but, if you were to move the asteroid to an elliptical orbit, would it become a comet?  And what about periodic comets that are now covered in rock and soot, no icy gas near the surface to sublimate and create a tail. Is it still a comet?

Earlier this summer, the third interstellar object discovered by humans is passing through. Now known as 3I/Atlas (Asteroid Terrestrial-impact Last Alert System) it does have a bit of a coma, like a comet, but on a hyperbolic orbit. The first object found (2017 now called Oumuamua) looked like a cigar shaped asteroid. It was too long to be from our solar system. It had Arthur C Clarke fans intrigued. The second object was discovered 2019 and first identified as a comet 21/Borisov. None of these three crossed Earth’s orbit, so no meteor shower from them. But what about other objects.  The Geminid shower is spawned by the Asteroid Phaethon which has many comet like features.

New telescopes with computer interfaces are capable of creating some really interesting images and information. If you are in the market for a ‘scope, check them out. Maybe you can get an Asteroid named for you some day.

When I was a child, there were nine planets even though I couldn’t see some of them. Asteroids we smaller than planets and most in orbit in the asteroid belt. Comets were thought to be from beyond our system. Now we think most comets come from the Oort Cloud and Kuiper Belt. Asteroids mostly stay in their belt, too. But there are blended families.

Clear Skies