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