See Mars and Venus on the summer solstice

The summer solstice is one of the biggest celestial events of the year and a major turning point in the calendar, but there isn’t much to see in the sky.

This year is different.

Earth, Mars, and Venus happen to be on the same side of the sun on this year’s solstice, and you can see Mars and Venus in the night sky near the slowly shining crescent moon. Low on the western horizon, just after twilight, you can find the rising crescent moon in a triangle with bright white Venus and faint red Mars. The parts of the moon that are usually dark and hidden in the lunar night will glow with a strange light that Leonardo da Vinci studied during the fifteenth century AD.

When the earth lights up the moon at night

Look closely at the crescent moon, and you’ll notice the dim outline 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 usually called the earth’s radiance. What you see is actually sunlight reflecting off clouds in Earth’s atmosphere – only for it to reflect back onto the moon’s surface, giving off a faint ghostly glow.

If you were to stand on the Moon as the long lunar night begins to wane, you would see the Earth glow in the night sky the way the full Moon does at night here on Earth – but about 50 times brighter. Future Artemis crews will actually get to experience this show one day; Astronauts on the Apollo missions came and went during the two-week lunar day, so they never saw a lunar night, let alone Earth’s glow.

A small telescope or a good pair of binoculars can give you a better view of the nighttime part of the moon’s surface that is submerged in Earth’s brightness. Look right along the terminator—the boundary between the daylit and dark parts of the moon—for the best view of the lunar surface’s mountains and craters, which are thrown in relief by the shadows of the lunar aurora.

There’s another chance to catch the alignment of your three closest celestial neighbors on Thursday night. The Moon will be slightly brighter, which may make Mars a little more difficult to spot, but Venus should still be clearly visible, and Earth’s brightness will still cast its faint light on the darkened surface of the Moon.