This week the moon visits neighboring planets, the Saturn nebula, and two of the brightest stars in the late autumn sky. (See also: "Stars: Billions and Billions.")
Moon Meets Mars
As darkness falls on Tuesday, November 25, look toward the low southwestern sky, where the thin, waxing crescent moon will be just left of the bright orange Mars. The pair will sit on top of the giant teapot stellar pattern within the constellation Sagittarius, the Archer.
In the early evening on Thursday, November 27, the crescent moon will have shifted high into the southwestern sky, into the constellation Aquarius, the Water Bearer.
Less than 2 degrees to its right sits the compact but bright Saturn nebula—not to be confused with the planet of the same name. The magnitude 7.8 nebula can be glimpsed with a small backyard telescope and is best seen under high magnification.
This deep-sky object takes its name from its appearance: 18th-century astronomers thought it faintly resembled the planet Saturn with its rings seen nearly edge on. But it's actually the gaseous remains of a sunlike star and is called a planetary nebula.
Lying some 3,900 light-years from Earth, the nebula measures about half a light-year across, and what we can see is the shell of glowing gas that formed when the central star ejected as much as 10 percent of its mass over a period of millions of years.
After nightfall on Friday, November 28, look for the first quarter moon between two of the brightest stars in the late autumn sky.
Fomalhaut, the brightest member of the constellation Pisces Austrinus, hangs to the moon's far lower left, while Enif, the nose of the mythical steed Pegasus, lies about an equal distance from the moon's upper right.
Moon and Neptune
Also on Friday night, the moon moves only 5 degrees away from ice giant Neptune.
A backyard telescope will be able to reveal the magnitude 7.9 planet's tiny bluish disk among the white stars in the background of the constellation Aquarius.
It's amazing to think that Neptune is so far away that light reflected from its clouds takes more than four hours to reach our eyes.
As darkness falls on Sunday, November 30, the waxing gibbous moon will slide over to the constellation Pisces high in the southern sky.
Block the glare of the moon with your hand, and you may be able to glimpse to its right the stellar pattern called the Circlet, which spans about 5 degrees of the sky.
This asterism, a group of stars that appear related but aren't, is the most easily recognized part of the constellation Pisces, the Fishes. Marking the head of the fish that points westward, this circular pattern of seven faint stars is barely visible with the naked eye in a moonless sky away from the light pollution of cities and suburbs.
This week the nearby moon will offer a convenient guidepost, but its glare will require you to use binoculars to track down the Circlet, no matter how clear the skies.