Before sunrise on April 8, 2018, the moon was at or near its last quarter phase. A last quarter moon always rises in the middle of the night, appears at its highest in the sky around dawn, and sets around midday. At last quarter, the lunar disk appears half-lit in sunshine and half-immersed in the moon’s own shadow. The lunar terminator – the shadow line dividing day and night – shows you where it’s sunset on the lunar terrain.
The April 8, 2018, last quarter moon was near the planets Mars and Saturn. See the photo below.
A last quarter moon provides a great opportunity to think of yourself on a three-dimensional world in space. For example, it’s fun to see this moon just after moonrise, shortly after midnight. Then the lighted portion points downward, to the sun below your feet. Think of the last quarter moon as a mirror to the world you’re standing on. Think of yourself standing in the middle of Earth’s nightside, on the midnight portion of Earth.
Also, a last quarter moon can be used as a guidepost to Earth’s direction of motion in orbit around the sun.
In other words, when you look toward a last quarter moon high in the predawn sky, for example, you’re gazing out approximately along the path of Earth’s orbit, in a forward direction. The moon is moving in orbit around the sun with the Earth and never holds still. But, if we could somehow anchor the moon in space … tie it down, keep it still … Earth’s orbital speed of 18 miles per second would carry us across the space between us and the moon in only a few hours.
Bottom line: The April 2018 last quarter moon – on the morning of April 8 – was be near the planets Mars and Saturn.
Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.org in 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. "Being an EarthSky editor is like hosting a big global party for cool nature-lovers," she says.