Saturn Mercury Duet At Dawn

Tomorrow morning, first spot the crescent moon about 45 minutes before sunrise. Then, look about a fist and half to the lower left for the duo of Saturn and Mercury. Mercury will be brighter than Saturn. To help you spot them, bring binoculars. Stellarium

I thought we were done with the planets after the crescent moon stopped by on Thursday next to Jupiter and Saturn at dawn. Not on your life. Two more vie for our attention lower down in the dawn sky: bright Mercury and returning Saturn. They’ll really get close too — less than 1° (⅘° to be exact) tomorrow morning.

The moon descends closer to the sun each of the next few mornings, forming new arrangement with Mercury and Saturn. Stellarium

To see this great little conjunction, you’ll need to be somewhere with a good view to the southeast because the planets will be only about 5° high (three fingers held at arm’s length). January marks the return of Saturn to the morning sky after its conjunction with the sun on Dec. 21, 2017. Like Jupiter and Mars before it, Saturn will gradually rise higher through the season and become easier to see. Meanwhile, Mercury is quickly dropping back toward the sun. It orbits inside Earth’s orbit and swings from one side of the sun to the other in just a matter of weeks — visible for a time at dawn and then at dusk.

Both planets reside in the constellation Sagittarius, which is just now returning to the dawn sky. Venus just returned to the evening sky after its recent conjunction, but it will be lost in the solar dazzle until about mid-February when we just might eke it out low in the west after sunset. I miss the evening planets but feel grateful for late sunrises that mean getting to see lots of planetary activity before breakfast these days.

Speaking of which, the sun began rising earlier starting on Sunday the 6th. That morning, it rose one minute earlier compared to the previous week. Sunsets have been getting later since Dec. 17. Since both are now working in synchrony to chip away at the night, we’ll soon notice the change in daylight length. Where I live we’ve added 23 minutes on the sunset end and 3 minutes on the sunrise side for a total gain in daylight of 26 minutes.

The reason sunrise and sunset don’t change at the same time after the winter solstice has to do with the angle of the sun’s path in winter and Earth’s orbital speed, which is faster in January because the planet is closest to the sun then. For a more thorough explanation, please check out this article I wrote on the topic.