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New moon comes on July 23

This July 23 new moon is the last one before the much-anticipated Great American Eclipse!

A new moon is more or less between the Earth and sun. Its lighted half is turned entirely away from us. This simulation of a new moon is via memrise.com.

The moon turns new on July 23, 2017 at 9:46 UTC. At North American time zones, that places the new moon at 6:46 a.m. ADT, 5:46 a.m. EDT, 4:46 a.m. CDT, 3:46 a.m. MDT, 2:46 a.m. PDT and 1:46 a.m. AKDT. A moon at the new phase comes most nearly – for any particular month – to passing between the Earth and sun.

This is the last new moon before the much-anticipated total solar eclipse of August 21, 2017. On that day, the day of the next new moon, the moon will pass between the sun and Earth. The moon’s shadow will fall on Earth. Those in the shadow’s path will witness the solar eclipse, a beautiful sight in the sky, and a dramatic turning of day to dark in the middle of the day.

Composite image of a 2006 solar eclipse by Fred Espenak.  Read his article on the August 21, 2017 total solar eclipse, first one visible from contiguous North America since 1979.

The next solar eclipse will be total and visible from North America. It’ll be the first total solar eclipse visible from contiguous North America since 1979. Read more about the August 21, 2017 total solar eclipse. Composite image of a 2006 solar eclipse by Fred Espenak.

For most of us – on the day of new moon – unless we’re viewing an eclipse of the sun, we won’t see the new moon.

That’s because a new moon rises when the sun rises. It sets when the sun sets. It crosses the sky with the sun during the day.

Modern techniques – telescopes, filters, photography – have made it possible to see the moon even at the instant it becomes new. That’s the case with Thierry Legault’s image, below, which he acquired in 2013. Read more about Thierry’s image here.

View larger. | Youngest possible lunar crescent, with the moon's age being exactly zero when this photo was taken — at the precise moment of the new moon - at 07:14 UTC on July 8, 2013.  Image by Thierry Legault.  Visit his website.  Used with permission.

Youngest possible lunar crescent, with the moon’s age being exactly zero when this photo was taken — at the instant of new moon – 0714 UTC on July 8, 2013. Image by Thierry Legault. Visit his website.

It’s only as the moon moves in orbit, as its lighted hemisphere begins to come into view from Earth, that we can see it in our sky. Then we see the moon in the west after sunset as a slim waxing crescent – what some call a young moon.

The moon will be more than one and one-half days old by evening at North American time zones on July 24. From around the world on July 24, you might be able to see the young moon return to the evening sky. Watch for it, near the sunset point, as soon as darkness begins to fall. Use your binoculars, and sweep along the western horizon. With luck, you’ll spot it and perhaps also see the star Regulus – Heart of the Lion in the constellation Leo – and the planet Mercury.

Watch for the young moon to sweep past the star Regulus and planet Mercury on July 24 and 25. Read more.

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

Total eclipse of the sun: August 21, 2017

Moon in 2017: Phases, cycles, eclipses, supermoons and more

Deborah Byrd

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