Some of your frequently asked Moon questions, answered.

Moon in Motion: Phases, Patterns, and More

  • Does the Moon rotate? Does the Moon spin on its axis?

    Yes! The time it takes for the Moon to rotate once on its axis is equal to the time it takes for the Moon to orbit once around Earth. This means that the same side of the Moon always faces our planet.

    If the Moon did not rotate on its axis at all, or if it rotated at any other rate, then we would see different parts of the Moon throughout the month.

  • Does the Moon orbit Earth?

    Yes. The Moon takes about one month to orbit Earth (27.3 days to complete a revolution, but 29.5 days to change from New Moon to New Moon). 

    As the Moon completes each 27.3-day orbit around Earth, both Earth and the Moon are moving around the Sun. Because of this change in position, sunlight appears to hit the Moon at a slightly different angle on day 27 than it does on day zero ― even though the Moon itself has already traveled all the way around Earth. It takes a little more than two additional days for sunlight to hit the Moon in the same way it did on day zero. This is why it takes 29.5 days to get from new moon to new moon, even though it doesn’t take quite that long for the Moon itself to travel once around Earth.  

  • Are Moon phases the same everywhere on Earth?

    Yes, everyone sees the same phases of the Moon. People north and south of the equator do see the Moon’s current phase from different angles, though. If you traveled to the other hemisphere, the Moon would be in the same phase as it is at home, but it would appear upside down compared to what you're used to! 

    For example, on March 8, 2021, the Moon was in a waning crescent phase. Seen from the Northern Hemisphere, the waning crescent appeared on the left side of the Moon. Seen from the Southern Hemisphere, the crescent appeared on the right.

    Waning crescent moon as seen from Northern and Southern Hemispheres
    Data visualizations of the waning crescent moon as seen from the Northern Hemisphere (left) and the Southern Hemisphere (right) on March 8, 2021. Credit: NASA’s Scientific Visualization Studio

  • Are Moon phases caused by shadows from Earth?

    No. The only time Earth’s shadow affects our view of the Moon is during a lunar eclipse. Generally, one half of the Moon ― the side facing the Sun ― is brightly illuminated, and one is in shadow. We use moon phases to describe the way our perspective on the half-lit Moon changes as Earth and Moon move through space over the course of a month. 

    During a crescent moon, for example, the part of the Moon that faces Earth is mostly in shadow, and the far side of the Moon is mostly sunlit. The visible crescent is the only part of the lunar nearside that is experiencing daytime.

    Waning Crescent Moon
    Data visualization of a waning crescent moon as seen from the northern hemisphere. During this phase, it is night on most of the near side of the Moon, and day on most of the far side of the Moon. Credit: NASA’s Science Visualization Studio

  • Why do we see Moon phases?

    The Moon is always half-lit by the sun (except during a lunar eclipse). The side of the Moon facing the Sun appears bright because of reflected sunlight, and the side of the Moon facing away from the Sun is dark. Our perspective on the half-lit Moon changes as the Moon orbits Earth. When the side nearest to us is fully lit, we call this a full Moon. When the far side is fully lit and the near side is dark, we call this a new Moon. When we see other phases, we are looking at the division between lunar night (the dark part) and day (the bright part).

  • What is the Moon really shaped like?

    The Moon is shaped like an imperfect sphere. From a distance, it looks nearly round. Seen up close, the Moon’s surface is a three-dimensional landscape of mountains, valleys, and craters. Explore the Moon’s surface from wherever you are in this 3D map built from data captured by NASA’s Lunar Reconnaissance Orbiter (LRO). 

    From Earth, our view of the Moon's sunlit surface changes throughout the month. Learn about crescent moons, full moons, and other moon phases here.

  • Can I see the Moon during the day?

    Yes! The Moon is up just as much during the day as it is at night, but you might not notice it as easily. Because the Sun is also up, and because the Moon phases that are most often visible in daylight show us only a little bit of the Moon’s bright side (like the crescent Moon phases), the Moon is harder to see during the day.

  • Why does the Moon rise and set? Can people in different countries see the Moon on the same day?

    Moonrises and moonsets occur for the same reason as sunrises and sunsets: Earth rotates once a day. This means that observers in many different parts of the world have their turn looking at the Moon throughout each day, just like we all see the same Sun over the course of 24 hours.

    Moonrise and moonset times change each day as the Moon moves through its monthly orbit around Earth. Learn more about the Moon's motion through space here

  • Why does the Moon look largest close to the horizon?

    This is an optical illusion. Prove it for yourself here!

Origin and Nature of the Moon

Quick Facts

Average Distance from Earth:
238,855 miles | 384,400 kilometers

Orbit and Rotation Period:
27.32 Earth Days

Equatorial Radius:
1,079.6 miles | 1,737.5 kilometers

0.0123 of Earth's (a bit more than 1 percent)

0.166 of Earth's (If you weigh 100 pounds (45 kilograms) on Earth, you'd weight 16.6 pounds (7.5 kilograms) on the moon)

Temperature Range:
-414 to 253 degrees Farenheit (-248 to 123 degrees Celsius)

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