The most elusive planet, little Mercury, pays a visit to the early evening skies this week, while the moon guides sky-gazers toward the true Lord of the Rings and other stellar delights.
Mercury rising. Just after sunset on Tuesday, January 21, and for the rest of the month, the closest planet to the sun, Mercury, will be at its best in the evening sky. The innermost world of our solar system sets about an hour after sunset, so there is a limited window of opportunity to see it with the naked eye or binoculars.
Since it is so close to the sun, very low in the southwestern sky, it is important to have an unobstructed view in the direction of sunset to see Mercury.
Lunar trio. Check out an amazing cosmic triangular formation in the southwestern sky at dawn on Wednesday, January 22. The waning gibbous moon will park itself to the right of Mars and Spica, the brightest star in the constellation Virgo. The red planet will appear only 4 degrees to the upper left of Earth’s natural satellite.
Blue-white Spica will be even closer to the moon—separated by only 2 degrees, equal to the width of four full moons as seen from Earth.
Moon and Spica. Less than 24 hours later, in the early morning hours of Thursday, January 23, check out the silvery quarter-moon as has an eye-catching close encounter with Spica, 262 light-years from Earth.
The cosmic odd couple will be less than 1 degree apart—about the same width as your thumb held at arm’s length.
While the moon is less than 1.5 light-seconds away from Earth, it’s amazing to think that the light that reaches your eye from Spica left on its journey back in 1751, the year when James Madison, the fourth president of the United States, was born and the first hospital in the American colonies was built in Philadelphia.
Saturn duo. The moon continues its trek across the southern sky each day, and by dawn Saturday, January 25, it will rest less than 2 degrees from the ringed planet, Saturn. For sky-watchers in the Southern Hemisphere in Antarctica, southern Argentina, and Chile, the planet will actually disappear from the sky, hiding behind the moon in what is called a lunar occultation. Elsewhere, the planet will be visible to the naked eye even from light-polluted cities, riding high in the south by local dawn. Even the smallest backyard telescope with high magnification will reveal the gas giant’s concentric rings and a handful of its 34 moons.
Antares and moon. Finally, about an hour before dawn on Sunday, January 26, look for the thinning crescent moon perched above the heart of the cosmic arachnid, Scorpio. The bright orange star, the red giant Antares, sits some 600 light-years away, yet it shines as the 16th brightest star in the entire sky because it is nearly 800 times larger than our sun.
If Antares were placed at the center of our solar system, its outer atmosphere would reach almost to Jupiter’s orbit, meaning Earth would be a cinder block within the belly of this stellar monster.