Moon facts
The Moon is 384,400 km from Earth on average, 3,475 km wide and takes 27.3 days to orbit Earth; new Moon to new Moon is 29.5 days.
Your date and place
Moon phase simulator
At 90° around its orbit the Moon is in the first quarter phase, with 50.0% of its disc lit.
Half of the Moon is always in sunshine. What changes is how much of that sunny half turns toward us as the Moon travels. The drawing looks down on the orbit from above Earth's north pole.
Moon watching sheet for ages 8 to 12
Put your name and today's date at the top. Name the four Moons below, then sketch the shape that comes after each.
1. __________________
2. __________________
3. __________________
4. __________________
- At what time of day does the full Moon come up?
- Is a quarter Moon a quarter of the disc, or half of it?
- Sketch the Moon that follows a thin waxing crescent.
Your Moon diary
| Day and hour | Sketch of the shape | Where I saw it, and the sky |
|---|---|---|
| ________________ | ________________ | ________________ |
| ________________ | ________________ | ________________ |
| ________________ | ________________ | ________________ |
| ________________ | ________________ | ________________ |
| ________________ | ________________ | ________________ |
Show the answers
The four Moons are the new Moon, the first quarter, the full Moon and the last quarter. A full Moon comes up around sunset. A quarter Moon shows half of the disc, because it is a quarter of the way around the orbit. After a waxing crescent comes the first quarter.
The Moon in numbers
- Average distance from Earth
- 384,400 km
- Width
- 3,475 km
- Surface gravity
- 1.62 m/s², about one sixth of Earth’s
- One trip around Earth
- 27.3 days
- New Moon to new Moon
- 29.5 days
- Apparent size in the sky
- about half a degree
The Moon needs 27.3 days to circle Earth, yet its phases repeat every 29.5 days. Earth keeps travelling around the Sun while the Moon orbits, so the Moon needs two more days to line up with the Sun again.
Why the Moon looks flipped in the Southern Hemisphere
Everyone sees the same phase at the same moment, but the picture turns with your latitude. At November 11, 2026 at 12:00 EST the Moon is waxing crescent. The two discs show it from a northern place (40.7°, -74.0°) and a southern one (-33.9°, 151.2°).
Northern view · Moon 18° above the horizon
Southern view · Moon -26° above the horizon
Earthshine: the faint glow on a crescent
On a thin crescent the dark part of the disc is not completely black. Sunlight bounces off Earth's oceans and clouds, lands on the Moon and bounces back to you. Look for it just after sunset a day or two after new Moon, or before dawn a day or two before it. Check whether the crescent is visible tonight.
Why the Moon turns orange or red
A Moon low over the horizon shines through a long slice of air that scatters blue light away, so it looks yellow, orange or red. A total lunar eclipse is redder still: the only light reaching the Moon has passed through Earth's atmosphere. Phone and camera settings can also shift a photo's colour. The Pink Moon is the name of an April full Moon, not a colour forecast.
The ring around the Moon
A bright circle around the Moon forms when high, thin cloud holds six-sided ice crystals that bend the moonlight. The ring sits 22° from the Moon, about the width of your hand held out at arm's length, and it says something about the cloud, not the phase.
Moon phase emoji and their codes
| Emoji | Phase | Code |
|---|---|---|
| 🌑 | New Moon | U+1F311 |
| 🌒 | Waxing crescent | U+1F312 |
| 🌓 | First quarter | U+1F313 |
| 🌔 | Waxing gibbous | U+1F314 |
| 🌕 | Full Moon | U+1F315 |
| 🌖 | Waning gibbous | U+1F316 |
| 🌗 | Last quarter | U+1F317 |
| 🌘 | Waning crescent | U+1F318 |
Copy an emoji straight from the table. Its artwork changes from one device to another, and all eight are drawn as seen from the Northern Hemisphere.
Essential lunar constants
Scale of the Moon
How big and how far is the Moon?
The Moon has a mean equatorial diameter of 3,474.8 kilometres, making it the fifth largest natural satellite in the Solar System and exceptionally large relative to its parent planet. If Earth were the size of a basketball, the Moon would be roughly the size of a tennis ball.
At an average distance of 384,399 kilometres, all seven other major planets in the Solar System could comfortably fit edge-to-edge in the space between Earth and the Moon. A laser pulse or radio signal travelling at the speed of light takes about 1.28 seconds to travel between the two bodies.
- Moon diameter
- 3,475 km (27% of Earth's 12,742 km)
- Mass ratio
- 1 / 81.3 of Earth's mass
- Volume ratio
- 1 / 50th of Earth's volume
- Light travel time
- 1.28 seconds from Moon to Earth
Surface physics
Gravity, atmosphere, and surface vacuum
Because the Moon is less dense than Earth and has only 1.2% of Earth's mass, its surface gravity is just 1.62 m/s²—roughly one-sixth (16.6%) of standard terrestrial gravity. An astronaut weighing 75 kg (165 lbs) on Earth weighs only 12.5 kg (27.5 lbs) on the lunar surface.
This low gravity, combined with the lack of a global magnetic field, prevents the Moon from retaining an atmosphere. Without air to scatter sunlight or carry sound, the lunar sky appears jet black even at high noon, and temperatures fluctuate wildly between scorching day (+120°C) and freezing night (-130°C).
- Atmospheric pressure
- 3 × 10⁻¹⁵ bar (hard vacuum)
- Escape velocity
- 2.38 km/s (vs Earth's 11.2 km/s)
- Weight reduction
- You weigh 83.4% less on the Moon
- Sky color on surface
- Pitch black even in broad daylight
Tidal locking
Why does the Moon always show the same face?
For billions of years, Earth's gravitational tidal forces acted on the Moon's molten interior, gradually slowing its axial rotation until its rotational period precisely matched its orbital period around Earth (27.32 days). This state is known as synchronous rotation or tidal locking.
As a result, the Moon always presents the same hemisphere toward Earth. The "far side" of the Moon was completely unknown to humanity until the Soviet Luna 3 spacecraft transmitted the first historic photographs in October 1959, revealing a rugged, crater-scarred terrain with almost none of the smooth volcanic basalt "seas" (maria) that characterize the near side.
- Rotation period
- 27.32166 days (identical to orbit)
- Locking mechanism
- Earth's tidal braking on lunar crust
- Far side discovered
- Soviet Luna 3 probe (October 1959)
- Far side topography
- Densely cratered, lacking large dark maria