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New moon is December 18

A new moon is a moon most nearly between the Earth and sun for any particular month. It crosses the sky with the sun during the day.

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.

The moon will new again on December 18, 2017 at 06:30 UTC. A moon at the new phase comes most nearly – for any particular month – to passing between the Earth and sun. The December 18 new moon will mark the beginning of the longest lunar month of the 21st century.

New moons come once each month, as the moon orbits Earth. On the day of new moon – unless we’re viewing a total solar eclipse, we don’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. Its fully illuminated face, or day side, is turned entirely away from us.

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, above, which he acquired in 2013. Read more about Thierry’s image here.

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.

Read more: December 18, 2017 new moon starts longest lunar month of 21st century

Total solar eclipse of August 21, 2017 by Fred Espenak at the Tate Geological Museum at Casper College, Wyoming, 1st one visible from contiguous North America since 1979. Every total solar eclipse, including the one of August 21, 2017 – was caused by a new moon.

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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