Venus occupies center stage in the evening sky but soon gets some company. Mercury enters the scene this week and next, poking a tentative head above the southwestern horizon two-and-a-half fists to the lower right of Venus. The planet will be quite bright at magnitude –1.0 — a near twin to Sirius — but low altitude and the twilight glow will make it appear fainter. Still, you should have no problem spotting the shy planet as long as you have a clear view of the west-southwest sky down to within a few degrees of the horizon.
Because Venus is so easy to see we’ll use it as a pointer to Mercury, which glimmers about 5° above the horizon 45 minutes after sunset. Slide downward and right from Venus toward the lingering glow of sunset, and you’ll spot a starlike point of light in the orange afterglow. That’s the innermost planet staring back! Mercury is always teasing us observers, making us work a little harder to find it that the other naked-eye planets.
There are two reasons for this. Mercury is relatively far away (twice as far as Venus) and orbits the sun closely. Its greater distance means we see both bodies along similar lines of sight, so they appear closer together. That and the fact that it already orbits nearer the sun than any planet, and you can understand why Mercury never gets far from the sun.
Like a dog on a short leash attached to a lawn stake, the planet runs around the sun in tight circles, never leaving the twilight glow of dusk or dawn. Venus on the other hand, orbits further from the sun and comes much closer to the Earth, so it really stands out on its own. Of course, it doesn’t hurt that Venus is 100 percent cloud-covered — clouds are efficient reflectors of sunlight.
Mercury will climb higher in the west in the coming evenings to a more comfortable 10° altitude by Valentine’s Day before sinking back toward the sun. If you’re struggling to see the planet because of haze, bring binoculars. Focus them sharply on Venus first and then hunt for the shy guy.
Dawn is not without its planetary pleasures. Early risers can spy three of these wandering stars during morning twilight. Red Mars and creamy Jupiter are easiest. Because of its low altitude I recommend binoculars for Saturn. Follow the arc from Mars to Jupiter and down toward the southeastern horizon to catch the ringed planet. Saturn will need another week to wrest itself from the bright glow of morning twilight into naked-eye visibility.
If you’re looking for a special Valentine’s Day gift, wake your special lady or man on that morning and lasso the trio the way Jimmy Stewart offered Mary the moon in “It’s a Wonderful Life.”