Sky ArchiveTonight

Saturn, Mercury, moon this weekend

The planets Mercury and Saturn are in conjunction on January 13, 2018, with Mercury passing some 0.7o south of Saturn. For reference, the moon’s diameter spans about one-half degree (0.5o) of sky. By coincidence, the moon is near the planets on these mornings. Great time to catch them!

Try catching the close pairing of Mercury and Saturn on January 13 or 14 as predawn darkness gives way to morning dawn. Look in the sunrise direction. The lit side of the waning crescent moon will be pointing in the direction of Mercury and Saturn, with these two planets sitting quite close to the sunrise point on your horizon.

Mercury will be the brighter of these two worlds.

One caution: Mercury and Saturn rise very shortly before the sun. So there is a narrow window for seeing them, before the dawn drowns them from view. Click here for recommended almanacs; they can give you the time of both sunrise and planet-rise in your sky.

You’ve got to look very low in the sky, near the sunrise point, to see Saturn and Mercury shortly before sunrise. William Eager caught them on January 11, 2018 from San Tan Valley, Arizona.

The rising times for Mercury and Saturn vary somewhat around the world, depending on where you are. At temperate latitudes in the Northern Hemisphere, these planets come up about one and one-quarter hours before the sun. At temperate latitudes in the Southern hemisphere, they rise about one and one-half hours before sunrise.

No matter where you live, however, you’ll want an unobstructed horizon in the direction of sunrise. Keep you binoculars handy, because the viewing is sometimes murky near the horizon.

After their January 13 conjunction, Mercury will fall toward the sunrise day by day, while Saturn will climb upward, away from the glare of daybreak. Thus Saturn will adorn the morning sky for many months to come. Meanwhile, Mercury will transition out of the morning sky and into the evening sky as this inferior planet reaches superior conjunction on February 17, 2018.

There are 2 other bright planets – easier to see – lighting up the January predawn sky right now. You’ll see the planets Jupiter and Mars above the moon, and the planets Mercury and Saturn below the moon on the mornings of January 12, 13 and 14. Click here for more on Jupiter and Mars.

Of course, Jupiter is the brightest starlike object in your morning sky. That’s true no matter where you are on Earth. And Mars is a short hop below Jupiter before dawn. Keep your eye on Saturn and Mars, and you’ll see these two planets edging closer and closer to one another over the next several months. Saturn and Mars will have their conjunction in early April 2018, with Mars swinging 1.3o south of Saturn on April 2, 2018.

Bottom line: The Mercury/Saturn conjunction is Saturday, January 13, 2018. Plus, on both Saturday and Sunday mornings, the moon will be pointing toward these planets near the sunrise.

January 13, 2018
Sky Archive

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Bruce McClure

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