Today, Oct. 21, 2025, the moon is 30 days old and is in the New Moon phase of its lunar cycle. It is 0% illuminated.

Learn how the Moon’s phases form, why it changes shape in the sky each night, and what each stage — from new moon to full moon — actually means.

This week in Skywatch, I want to go back to basics when it comes to the moon. So why does the moon change shape? Why is it a crescent on one night, a half-moon another night, and a full moon on yet ...

When the moon is nearly between Earth and the sun, one side of the moon faces the sun, and that side is illuminated, but the side the Earth sees is dark. This is called the new moon phase of the lunar ...

Check today’s Moon phase and explore the full lunar calendar for 2025, showing each stage from new moon to full moon throughout the year.

This article was originally published at The Conversation. The publication contributed the article to Space.com's Expert Voices: Op-Ed & Insights. The moon is getting 1½ inches (3.8 centimeters) ...

Moon phases reveal the passage of time in the night sky. Some nights when we look up at the moon, it is full and bright; sometimes it is just a sliver of silvery light. These changes in appearance are ...