Mercury and Mars vie for attention in early morning skies

Wednesday, September 6, 2017

Jupiter and Saturn continue occupying the evening sky this month, but the best planetary show happens just before sunrise, starring Mercury, Venus and Mars.

Beginning in the west after sunset, the king of planets, Jupiter sits barely above the horizon. It's brilliance makes it easily stand out against the background stars. Jupiter rapidly descends toward the setting sun each evening this month, so the window for viewing this mighty world is rapidly closing.

Still occupying the southern sky is the ringed-world Saturn, although this month finds Saturn migrating westward. Saturn's rings can be seen even in a small telescope. The rings are tilted at a highly inclined angle with respect to earth, making for great viewing.

The must-see planetary display this month belongs to the morning sky, with three planets lining up for our viewing pleasure. At month's onset, it's easy to spot bright Venus in the east before sunrise, as it outshines all the stars. Venus stands alone in the morning at month's onset, but it's not long before two more planets join the mix.

Through the first half of the month, looking east, Mercury and Mars steadily ascend above the soft glow of morning twilight. By Sept 10, they should be high enough for viewing around 6:30 am. Venus, Mercury and Mars form a diagonal line, with Venus above, Mercury below and finally Mars, just a little below Mercury.

Each morning, Mercury and Mars move closer together until the 16th, when they form a very close conjunction and should be easily visible together in a pair of binoculars or a telescope at low power. After the 16th, the two planets switch places with Mercury below and Mars rising above. Then on the morning of Sept 17 and 18, the thin crescent moon joins the planetary trio, On the 17th, the moon is above Venus and the next morning, the razor thin crescent moon slides below Venus but above Mars and Mercury. The four line up vertically forming a stunning celestial display before dawn.

For viewing go out between 6 and 6:30 am, and look toward the east. Make sure you have an unobstructed horizon as Mars and Mercury are fairly low in the sky.

Brad Nuest is a space science educator at the Cosmosphere and writes a monthly column about the local skies for the Hutchinson News. Reach him at