The month of September marks many changes. For skywatchers it means the passing of the season's trademark Summer Triangle of stars and the arrival of the autumn constellations.
Flying high in the autumn sky is the mythical winged horse Pegasus.
Although one of the largest constellations in area, it boasts no bright stars. Its most noticeable star pattern is the Great Square of Pegasus: four second magnitude stars marking the body of the horse. Ironically, the brightest of those stars, Alpheratz, isn't even an official member of the Pegasus constellation, being part of the neighboring constellation Andromeda.
This sky map shows some of September constellations visible in the night sky, along with the planets Jupiter and Uranus.
The brightest star in Pegasus isn't part of the Square: it is Enif, the Arabic word for "nose." It marks the head of Pegasus, off to the west.
Surrounding Pegasus on three sides is a strange assortment cosmic objects named after mythical sea creatures.
To the west of Enif, half way to the star Altair in the constellation Aquila, is Delphinus the Dolphin ? one of the few constellations which actually resembles its namesake. Below Pegasus are three of the least prominent members of the zodiac constellations: Capricornus, Aquarius, and Pisces.
There's not a bright star in the lot.
As you look further south, you can see Piscis Austrinus, the southern fish, with the only bright star in the region: Fomalhaut. Fomalhaut, which is 25 light-years from Earth, made headlines in 2008 as one of the first stars to observed to have a planet that was directly imaged with telescopes.
To the east of Fomalhaut is another huge dim constellation, Cetus the Whale, with the only other brightish star in the area, Deneb Kaitos, which means the tail of the whale. Cetus also contains the variable star Mira. Currently this star is too faint to be visible with the naked eye, but over the next few months it will start climbing in brightness until it becomes one of the brightest stars in this constellation.
Normally this sea world is a dim and mysterious place, with only one bright star, Fomalhaut. But this year it is enlivened by a visit from the giant planet Jupiter, right on the border between Pisces and Aquarius.
With the aid of binoculars or a small telescope, you may be able to spot two more planets, Uranus and Neptune. Also located in this area, but far beyond the range of amateur telescopes, is the dwarf planet Eris.
Moving slowly through the constellation Cetus. Eris is a Kuiper Belt Object, one of the most recent discoveries in the solar system. It is larger than Pluto and farther from the sun.
- Amazing Night Sky Photos of Planets
- Telescopes for Beginners
- Observing the Night Sky: Getting Started
This article was provided to SPACE.com by Starry Night Education, the leader in space science curriculum solutions.