Last quarter moon on November 8

The moon you’ll see on the morning of November 8, 2020, will be at or near its last quarter phase. No matter where you are on Earth – as dawn breaks – it’ll be close to its high point on your local meridian – the imaginary semicircle that crosses your sky from due north to due south. Incidentally, the sun transits or crosses your local meridian at solar noon (sometimes called midday, high noon or local apparent noon).

The sun crosses your local meridian – the imaginary semicircle that crosses the sky from due north to due south – at local noon. A last quarter moon is crossing your meridian around dawn.

The moon’s half-lit last quarter phase comes on November 8, at 13:46 Universal Coordinated Time (UTC). For United States time zones, that translates to November 8, at 8:46 a.m. EST, 7:46 a.m. CST, 6:46 a.m. MST and 5:46 a.m. PST.

People sometimes ask us why the half-illuminated moon is called a quarter moon. It’s because at first quarter moon, the moon has completed one-quarter its journey between successive new moons. At last quarter moon (sometimes called third quarter moon), the moon has completed three-quarters of its journey between successive new moons. By definition, one lunar month ends and another lunar month begins at new moon.

Last quarter moon is synonymous with the moon being at western quadrature (90 degrees west of the sun in ecliptic longitude). If you could look down upon the lunar orbit from way up high, you’d see the sun-Earth-moon making a 90-degree angle at first and last quarter moons, with the Earth at the vertex of this right angle. The illustration below helps to explain.

A quarter moon takes place whenever the sun-Earth-moon angle makes a right angle in space, with our planet Earth being at the vertex of this right angle. Image via Wikipedia.

Because the last quarter moon is 90 degrees west (ahead) of the sun, the moon at the vicinity of its last quarter phase crosses your local meridian approximately 6 hours before the sun crosses your local meridian at solar noon. Also, since the last quarter moon resides 90 degrees west of the sun, this month’s half-lit last quarter moon shines in front of the constellation Cancer the Crab, or about where the sun was positioned upon the zodiac some three months ago.

Click on Heavens-Above for the moon’s position in the zodiac

Click on Heavens-Above for the sun’s position in the zodiac

Outer planet at quadrature.

When a superior planet – a planet that orbits the sun outside of Earth’s orbit – lies 90 degrees east or west of the sun in our sky, that planet is said to be at quadrature. If you could have been privy to a bird’s-eye view of the solar system when Mars was last at western quadrature on June 6, 2020, you would have seen the sun-Earth-Mars making a 90-degree angle in space, with our planet Earth at the vertex of this right angle. Mars will next reach eastern quadrature on February 1, 2021.

Unlike our moon, the planets never display a quarter phase at quadrature. Superior planets are always full, or close to full, though they display a minimal phase at quadrature.

Read more: Do the outer planets have phases?

Bottom line: Get up early, around the break of day on November 8, 2020, to see the moon at or near its last quarter phase, and close to your local meridian. This November last quarter moon assumes the position of the early August noonday sun.

Bruce McClure