Are you an early morning person, up and about during the predawn/dawn hours? If so, let the old waning crescent moon serve as your guide to the morning lineup of celestial lights: Spica, the constellation Virgo‘s brightest star, plus the planets Mars and Mercury.
On the morning of November 22, as seen from around the world, the lit side of the moon points at a string of celestial lights, with Spica reigning at top, Mercury at bottom and Mars in between. In terms of brilliance, Mercury is the brightest of the threesome, followed by 1st-magnitude Spica and then 2nd-magnitude Mars.
At present, Spica is about twice as bright as Mars; whereas Mercury is more than twice Spica’s brightness. That doesn’t necessarily mean Mercury will be the easiest of the bunch to see, however. Mercury will sit the lowest in the sky and closest to the glare of the sun.
It’ll be easier to observe the morning attraction at northerly latitudes than at southerly latitudes. At temperate latitudes in the Southern Hemisphere, these heavenly bodies rise quite close to sunrise.
We give the approximate rising times of Spica, Mars and Mercury for various latitudes:
35 degrees north latitude:
Spica rises 2 3/4 hours before the sun
Mars rises 2 1/4 hours before the sun
Mercury rises 1 1/2 hours before the sun
Equator (0 degrees latitude):
Spica rises 2 1/3 hours before the sun
Mars rises 1 3/4 hours before the sun
Mercury rises 1 1/10 hours before the sun
35 degrees south latitude:
Spica rises 2 hours before the sun
Mars rises 1 1/3 hours before the sun
Mercury rises 3/4 hour before the sun
Want more specific information? Click here for a recommended sky almanac.
Arcturus, the brightest star to adorn the eastern morning sky, shines to the upper left of the celestial line-up at mid-northern latitudes. At the equator (0 degrees latitude), Arcturus is seen to the left (not the upper left) of Mars and Mercury. At temperate latitudes in the Southern Hemisphere, Arcturus is not visible because it rises around or after sunrise in that part of the world.
Day by day, watch the waning (shrinking) lunar crescent sink closer and closer to the sunrise point on the horizon. The moon will bypass Spica on or near November 23, pair up with Mars around November 24, and then meet up with Mercury on November 25. New moon will come on November 26 – at which juncture, the moon will pass more or less in front of the sun, to transition out of the morning sky and into the evening sky.
Visit Sunrise Sunset Calendars to find out when the moon rises into your sky, remembering to check the moonrise and moonset box.
For the Northern Hemisphere, this morning apparition of Mercury counts as a particularly good one, so Mercury should be fairly easy to see with the eye alone for the next several weeks. What’s more, Mercury is brightening by the day. On November 23, Mercury will match Arcturus in brightness; and by the month’s end, Mercury will be about 1 1/2 times brighter than Arcturus.
At temperate latitudes in the Southern Hemisphere, you’ll probably need binoculars to spot Mercury. At southerly latitudes, Mercury rises a short while before the sun and sits in the harsh glare of morning twilight.
Bottom line: Enjoy the morning spectacle over the next several mornings, as the waning crescent moon sweeps by the star Spica and then the planets Mars and Mercury.
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.