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Moon: NASA's Lunar Portal
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Moon Facts
Moon Fact
Inverted Moon

As the astronomical telescope with its inverted image came into use, astronomers adopted the habit of representing the way they saw the moon -- upside down. This practice was followed until very recently. Lunar images are now constructed and stored digitally and can be displayed at any orientation. The moon is now typically shown right side up.

EYES on LADEE: Explore the Moon in 3D
Moon Facts
Out of Shape

The moon is not round, but is in fact egg-shaped with the large end pointed towards Earth.

Stuffed Crust

The crust on the far side of the moon is thicker than the crust on the near side.

The far side highlands appear to have formed early in the moon's history, when a magma ocean (shaped by tides caused by Earth's gravity) heated the moon's floating crust non-uniformly. Since then, the magma ocean has solidified.

Prince of Tides

There are two high tides and two low tides every day on every beach on Earth. This is due to the moon's pull.

Massive Impact Basin

Did you know the largest impact basin in the Earth-moon system is the South-Pole-Aitken basin on the moon measuring 2,500 km in diameter?

Moon Gods

Most ancient religions had a moon god or goddess. One Roman moon goddess was named Luna, and this is why many modern words associated with the moon have "Luna" as their root.

Deep Impact

The moon's deepest craters are 4,500 m (15,000 feet). The South Pole-Aitken basin on the moon is an abyss that could engulf the United States from the East Coast through Texas.

Moon Phases

Full moons occur every 29.5 days. The moon keeps the same side to us, but not always the same face. Because of the tilt and shape of its orbit, observers see the moon from slightly different angles over the course of a month.

Orange Rocks on the Moon

How did orange soil appear on the moon? This mystery began when astronaut Harrison Schmidt noticed the off-color patch near Apollo 17's Taurus-Littrow landing site in 1972. Astronauts scooped up some of the unusual orange soil for inspection back on Earth. Lunar geologists now think that the orange soil was created during an ancient fire-fountain.

Once in a Blue Moon

About every 2.5 years an extra full moon, called a "Blue Moon" occurs.

The term Blue Moon is believed to have originated in 1883 after the eruption of Krakatoa. The volcano put so much dust in the atmosphere that the moon actually looked blue in color. This was so unusual that the term "once in a Blue Moon" was coined.

First Step

The first human being walked on the moon on 20 July 1969.

The Moon's Earth-like Core

Research suggests the moon possesses a solid, iron-rich inner core with a radius of nearly 150 miles and a fluid, primarily liquid-iron outer core with a radius of roughly 205 miles. Where it differs from Earth is a partially molten boundary layer around the core estimated to have a radius of nearly 300 miles.

Original Rocks

The rocks of the terrae (the light colored, rugged highlands of the moon) are nearly 4.6 billion years old.

Tiny Temblors

"Moonquakes" are millions of times less powerful than earthquakes.

One Small Step ...

In 2009, a NASA team restored the first grainy video of Neil Armstrong's first step on the moon.

Earth Lashing

Every month when the moon gets a lashing from Earth's magnetic tail. This has consequences ranging from lunar "dust storms" to electrostatic discharges.

Lunar Celebration

The ancient Chinese greeted solar eclipses by using noisemakers and by shooting arrows toward the heavens.

Lunar Mascons

Mass is not distributed uniformly inside the moon. Large mass concentrations ("mascons") lie beneath the surface of many large lunar basins and probably represent thick accumulations of dense lava. Relative to its geometric center, the moon's center of mass is displaced toward Earth by several kilometers.

Constant Companion

It takes about a month for the moon to orbit Earth (27.3 days to complete a revolution, but 29.5 days to change phases from new moon to new moon).

Common Thread

Scientists think that a large object, perhaps the size of Mars, impacted our young planet and knocked out a chunk of material that eventually became our moon. Distinctive oxygen isotopic compositions of moon rocks and Earth rocks show a common ancestry.

Don't Forget Your Space Suit

The moon is 239,000 miles away from the Earth. It would take almost nine years to walk there.

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Last Updated: 11 Jul 2013