The two planets that are closer to the Sun than Earth — the so-called “inferior” planets, Mercury and Venus — are now in the morning sky, low in the east-northeast sky before sunrise. One is difficult to see; the other much easier, primarily due to its great brilliance.
Fun Fact: Why are Mercury and Venus called “inferior” planets? Because they lie closer into the Sun than the Earth.
Mercury, the planet nearest to the Sun, reaches its greatest elongation of 26°, the farthest west of the Sun it gets in 2017, on May 17th. But this is the worst time to view it for northerners, because the ecliptic then forms a small angle with the predawn horizon. For the rest of May the inner planet is only 1° above the horizon in mid-twilight (50 minutes before sunup) for latitude 40° north.
Scan the horizon with binoculars about 15° north of east. From more southerly states, Mercury will be a few degrees higher and possibly accessible to the unaided eye, and if you live in the Southern Hemisphere, it is comfortably well up in the east as dawn brightens.
On Sunday morning, May 21st, early risers should check out the eastern sky after 4:00 a.m. local daylight time to catch sight of a lovely pairing: the waning crescent Moon, and shining to its upper left, Venus, the dazzlingly bright Morning Star for this spring and summer. Venus attained its greatest brilliancy (magnitude -4.7) on April 30th, but it is practically at that level of brightness now.
During the month of May those using a telescope have watched as Venus has transformed from a 27 percent illuminated crescent at the start of the month to become almost half-lit (48 percent) by month’s end, shrinking all the while.
If you capture photos of these planets be sure to share your photos with us on our Facebook page.