The summer solstice is one of the biggest celestial events of the year and a major turning point in the calendar, but there’s usually nothing to see in the sky.
This year is different.
Earth, Mars and Venus happen to be on the same side of the Sun for this year’s solstice, and you can see Mars and Venus in the night sky very close to the slowly glowing crescent moon. Low on the western horizon, just after dusk, you can find the waxing crescent moon in a triangle with bright white Venus and dark red Mars. And parts of the moon that are normally dark and hidden by the moonlit night will glow with an eerie light that Leonardo Da Vinci studied in the 1500s.
TOPSHOT – The sun rises at Stonehenge, near Amesbury, in Wiltshire, southern England, on June 21, 2023, during the summer solstice festival, which dates back thousands of years, celebrating the longest day of the year when the sun is at its maximum height. The stone monument – carved and constructed in a time when there were no metal tools – symbolizes Britain’s semi-mythical prehistoric period and has spawned countless legends. (Photo by Daniel LEAL / AFP) (Photo by DANIEL LEAL / AFP via Getty Images)
DANIEL LEAL/AFP/Getty Images
When Earth lights up the moonlit night
Look closely at the crescent moon and you will notice faint outlines of the Full Moon. Historical sources call this “the old moon in the arms of the new moon” or describe it as an “ash glow”, and today it is commonly called the Earthshine. What you’re actually seeing is sunlight reflecting off clouds in Earth’s atmosphere—only to bounce back off the surface of the Moon, casting a faint ghostly glow.
If you’re standing on the Moon as the long lunar night begins to fall, you’ll see Earth glow in the night sky the way a full moon lights up the night here on Earth—but about 50 times brighter. Future Artemis crews would indeed experience this sight someday; the astronauts on the Apollo missions came and went during the two-week lunar day, so they never saw a lunar night, much less the glow of Earthshine.
A small telescope or good binoculars can give you a better view of the night-shrouded part of the lunar surface, bathed in an earthy glow. Look to the right past the terminator—the boundary between the moon’s daylight and dark side—for the best view of mountains and craters on the moon’s surface thrown into sharp relief by the shadows of lunar twilight.
There’s one more chance to catch the alignment between our three closest celestial neighbors on Thursday night. The moon will be a little brighter, which may make Mars a little harder to spot, but Venus should still be clearly visible and Earthshine should still cast its faint light on the dark lunar surface.