Don’t expect to see the planets Uranus and Neptune in the glare of tonight’s waxing gibbous moon. But you can use the moon on the night of October 25 to get a ballpark idea of where these distant planets reside in front of the backdrop stars. Not that you’ll see many stars in this region of the sky tonight, except for Fomalhaut, and the four stars in the Great Great Square of Pegasus.
Star-hop to Fomalhaut from the Great Square of Pegasus
Fomalhaut resides to the south of tonight’s moon, while the Square of Pegasus lies to the north. From northerly latitudes, that means the Great Square of Pegasus appears high overhead or high in the southern sky, while Fomalhaut shines low in the south. From temperate latitudes in the Southern Hemisphere, Fomalhaut shines high overhead, whereas the Great Square of Pegaus appears in their northern sky.
As seen from around the world tonight, the moon shines fairly close to the border of the constellations Aquarius and Pisces. Uranus lies to the east of the tonight’s moon, in front of the constellation Pisces, and Neptune is to the west of the moon, in front of the constellation Aquarius.
Note the ecliptic on the feature chart at top. The ecliptic depicts the Earth’s orbital plane projected onto the stellar sphere. Because the planets of the solar system circle the sun on nearly the same plane that the Earth does, practiced sky watchers know to look for the planets on or near the ecliptic.
Neither one of these planets is particularly easy to locate or to see. Uranus, the seventh planet outward from the sun, barely makes the grade as a naked-eye object on a dark, moonless night. Neptune, the eighth planet outward, isn’t visible to the unaided eye at all, so you absolutely need an optical aid to see Neptune, the solar system’s most distant planet.
If you want to find these two distant worlds, you really need to familiarize yourself with the constellations Aquarius and Pisces. With a good sky chart, and lots of patience, you can star-hop to Uranus and Neptune.
Wait for a dark, moonless evening to seek out the solar system’s two most distant planets. The moon will drop out of the evening sky by around the second week of November 2012.
In the meantime, tonight’s moon guides you to the great Square of Pegasus, the star Fomalhaut and the general location of Uranus and Neptune in your sky.