For the next few mornings – January 23-25, 2017 – get up before dawn to catch the waning crescent moon with the bright ruddy star Antares and marginally-brighter, golden planet Saturn. If your timing is just right, you might be able to spot Mercury as well.
The moon will be moving past Saturn and Antares on these mornings. Notice that, on the morning of January 23, the moon Saturn and Antares make a triangle on the sky’s dome for us in North America, as shown on the chart below.
If you’re up early enough, you might also see the head of Scorpius the Scorpion sticking up above the horizon. It takes the form of a little arc of three moderately bright stars, located to the west of Antares. Their names are Graffias, Dschubba and Pi Scorpii. They’re sometimes called the Crown of the Scorpion.
The northernmost of these three stars, Graffias, serves as your guide to the planet Mercury as darkness begins to give way to dawn. Draw an imaginary line from Graffias through Saturn to find out where the planet Mercury will be climbing over the horizon.
Seek for Mercury around 90 to 75 minutes before sunrise. Click here for an almanac giving you Mercury’s rising time into your sky.
Mercury is actually brighter than either Saturn or Antares. However, Mercury sits lower in the sky and lurks quite close to the horizon, so Mercury might not appear brighter to your eye. If the seeing conditions are less than ideal, try your luck spotting Mercury with binoculars.
Bottom line: Given clear skies, it should be easy to use the waning crescent moon to locate the star Antares and planet Saturn before dawn’s first light on January 23, 2017.
Bruce McClure has served as lead writer for EarthSky's popular Tonight pages since 2004. He's a sundial aficionado, whose love for the heavens has taken him to Lake Titicaca in Bolivia and sailing in the North Atlantic, where he earned his celestial navigation certificate through the School of Ocean Sailing and Navigation. He also writes and hosts public astronomy programs and planetarium programs in and around his home in upstate New York.