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Where is the moon? Last quarter

Fun time to see a last quarter moon: just after it rises, shortly after midnight. Then the lighted portion points downward, to the sun below your feet.

Last quarter moon - June 27, 2016 - from our friend Lunar 101 Moon Book on Facebook.

(Nearly) last quarter moon – the morning of June 27, 2016 – from our friend Lunar 101 Moon Book.

The last quarter moon comes on June 27, 2016 at 1819 UTC. Translate to your time zone. A last quarter moon looks half-illuminated. It rises around midnight, appears at its highest in the sky at dawn, and sets around noon.

Last quarter moon comes about three weeks after new moon. Now, as seen from above, the moon in its orbit around Earth is at right angles to a line between the Earth and sun. The moon is now three-quarters of the way around in its orbit of Earth, as measured from one new moon to the next.

It’s very cool to see the last quarter moon just after it rises, around midnight. Just after the last quarter moon rises, its lighted portion is always facing downwards, more or less toward the horizon. Why? Because you’re on the midnight portion of Earth – with the sun below your feet – just as it’s below this moon.

After the last quarter phase, the moon will begin edging noticeably closer to the sun again on the sky’s dome. Fewer people notice the moon during the day from about last quarter on, because the sun’s glare begins to dominate the moon.

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 at a last quarter moon high in the predawn sky, 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. 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.

May 29, 2016 last quarter moon posted to EarthSky Facebook by Deirdre Horan in Dublin, Ireland.  Thanks, Deirdre!

Last quarter moon by Deirdre Horan in Dublin, Ireland. Looks like she caught it around sunup, when the last quarter moon is high in the sky. Thanks, Deirdre!

As the moon orbits Earth, it changes phase in an orderly way. Follow these links to understand the various phases of the moon.

Four keys to understanding moon phases

Where’s the moon? Waxing crescent
Where’s the moon? First quarter
Where’s the moon? Waxing gibbous
What’s special about a full moon?
Where’s the moon? Waning gibbous
Where’s the moon? Last quarter
Where’s the moon? Waning crescent
Where’s the moon? New phase

Moon in 2016: Phases, cycles, eclipses, supermoons and more

Deborah Byrd

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