11 Spectacular Facts About the Moon

Matt Cardy/Stringer, Getty Images
Matt Cardy/Stringer, Getty Images

The Moon is Earth’s closest satellite in our solar system, but in many ways, we hardly know our neighbor. Scientists aren’t entirely sure how it formed, and other facts, like its shape (more egg-like than spherical), and the consistency of its surface (dusty but firm), were confirmed only recently. With the 50th anniversary of the Apollo 11 Moon landing this year, and NASA preparing to return to the lunar surface for the first time in decades, it’s time to brush up on these facts about the Moon—from colorful names for full moons to the first landing on the dark side of the Moon.

1. The Moon may have formed when a giant object in the solar system hit Earth.

Scientists aren't in total agreement on how the Moon formed, but the most widely accepted theory is the giant impact hypothesis. According to this theory, an object the size of Mars called Theia collided with Earth 4.5 billion years ago when the solar system was still new and chaotic. The impact dislodged matter from Earth’s crust, and the debris attached to whatever was left of Theia through the force of gravity.

This scenario would explain why the Moon is made up of lighter elements found in Earth’s outer layer, but it still leaves some questions unanswered. If the giant impact hypothesis is correct, about 60 percent of the Moon should consist of the impact object. Instead, its composition is almost identical to that of Earth. There are alternative explanations: one posits that the Moon is a space object that got caught in Earth’s orbit, and another one suggests the Moon and Earth formed at the same time, but none is as popular as the giant impact theory.

2. The Moon is the perfect size for solar eclipses.

Moon covering sun during solar eclipse.
Masashi Hara/Getty Images

A lucky set of circumstances make total solar eclipses, as seen from Earth, possible. The Moon is just the right size and distance from our planet to appear as the same size as the Sun in the sky. When the Moon passes between the Sun and the Earth, it covers the Sun perfectly with an impressive corona illuminating its edges. If it were any smaller or farther from Earth, it would look like a blot on the Sun during a solar eclipse.

3. A full Moon has different nicknames in different seasons.

A full moon can have many colorful names, but they don’t always describe a special celestial phenomenon. Some are used to refer to a full moon that appears during a certain time of year. A harvest moon, which is the full moon closest to the autumn equinox, is the best-known example, but there are many others, including a wolf moon (first full moon of January), strawberry moon (June), and sturgeon moon (August).

4. It’s the largest moon in the solar system relative to its planet.

Our Moon isn’t the largest in the solar system (that distinction goes to Ganymede, one of Jupiter’s 79 moons), but it is the biggest in relation to the planet it orbits. With a diameter of 2159 miles and a surface area of 14.6 million square miles, the Moon is a little more than one-fourth the size of Earth. The dwarf planet Pluto has an even smaller moon-to-planet ratio. Pluto’s largest moon Charon is nearly the size of its host body, leading some astronomers to refer to the pair as a double-dwarf planet.

5. The Moon is shaped like a lemon.

The Moon may look perfectly round in the night sky, but it’s actually more of an oval shape. It came out wonky billions of years ago when super-hot tidal forces shaped its crust, heating up some areas hotter than others to form a lemon shape rather than a perfect sphere. Gravitational forces from Earth have helped to exaggerate the Moon’s oblong appearance over eons.

6. Scientists thought Moon dust would cause lunar landers to sink.

Lunar module over moon's surface.
NASA/Newsmakers

When preparing to send missions to the Moon, some scientists feared that a thick layer of dust on the body’s surface would cause complications. One of the strongest proponents of the dust theory was Thomas Gold, an astrophysicist at Cornell University. He insisted that the Moon was covered in seas of dust soft and thick enough to swallow a lunar lander. Though the Moon’s surface is dusty, the layer is too thin to cause problems, as the successful landings of the Soviet Luna 9 and the American Surveyor spacecrafts proved in 1966.

7. The Moon is international property.

Astronauts Buzz Aldrin and Neil Armstrong may have planted an American flag on the Moon in 1969, but it belongs to the world. Countries like the Soviet Union and the U.S. made sure of that at the height of the space race in 1967 when they signed the Outer Space Treaty, a document declaring that the Moon would be a “global commons” and any resources discovered there would be used for the good of the world overall. In keeping with the spirit of the agreement, NASA shared soil samples taken from the Moon with Soviet scientists upon the Apollo 11 mission's return.

8. Humans have left strange things on the Moon.

Since the first people landed on the Moon in 1969, its surface has been home to more than just dust. Earth artifacts left on the Moon by astronauts include two golf balls, an obscene Andy Warhol doodle, and a message from Queen Elizabeth II. Eugene Cernan, Apollo 17 commander and one of the last people to walk on the Moon, traced his daughter’s initials into the soil when he visited in 1972. Without any wind or weather on the Moon, the letters TDC could remain there forever.

9. The "dark side of the Moon" is the result of synchronous rotation.

Even though the Moon is constantly rotating, only one side of it is visible from Earth. This is because the Moon is locked in synchronous rotation. It takes the Moon just as long to complete one full rotation as it does for the body to orbit around the Earth once, so the same side always faces our planet. This isn’t a coincidence—the Earth’s gravitational forces have gradually pulled the tip of the slightly oblong Moon to point toward the planet, creating something called tidal lock.

In January 2019, the Chinese space agency landed the first lunar probe on the unexplored dark side of the Moon. The Chang'e 4 spacecraft sent the first photographs of a massive impact crater on the dark side to Earth, giving scientists their first glimpse of that unknown region.

10. One astronaut was allergic to the Moon.

Apollo 17 astronaut Harrison “Jack” Schmitt discovered the hard way that some people are allergic to Moon matter. Following a survey of a valley in the Sea of Serenity, he climbed back into the crew’s lunar module and tracked in a lot of Moon dust with him. The dust affected him as soon as he removed his spacesuit, triggering red eyes, sneezing fits, and other symptoms that lasted two hours.

11. Humans are going back to the Moon soon.

After completing several manned missions to the Moon, NASA ended the Apollo program in 1972 as budgets tightened and public interest waned. That means most people alive today have never witnessed a manned lunar landing, but now, following a hiatus nearing 50 years, NASA is finally preparing to return to the Moon. The next manned lunar expedition will be ready to launch “no later than the late 2020s,” according to the space agency. One of the goals will be placing a command module, called Gateway, in the Moon’s orbit that astronauts can reuse over multiple missions.

NASA's First All-Female Spacewalk is Really Happening This Time

NASA astronaut Christina Koch is suited up in a U.S. spacesuit ahead of her history-making spacewalk.
NASA astronaut Christina Koch is suited up in a U.S. spacesuit ahead of her history-making spacewalk.
NASA

After a surprising cancellation in March, plans for NASA's first all-female spacewalk are back on track. Astronauts Christina Koch and Jessica Meir are scheduled to make history on October 21, 2019.

Earlier this year, NASA canceled the first all-female spacewalk because of an issue with spacesuit sizing. Both astronauts originally scheduled for the walk needed medium-sized suits. At the time, the International Space Station had two—but only one was properly configured for a spacewalk. Preparing the other suit in time would have taken hours of crew labor, The New York Times reported, so NASA decided to switch out the astronauts.

“When you have the option of just switching the people, the mission becomes more important than a cool milestone,” NASA spokesperson Stephanie Schierholz told The New York Times.

Still, the milestone is a significant one. Since 1961, nearly 550 people have been sent to space. Of those, only about 11 percent have been female.

“I think it’s important because of the historical nature of what we’re doing and in the past, women haven’t always been at the table,” Koch said on NASA TV. “There are a lot of people that derive motivation from inspiring stories from people who look like them, and I think it’s an important aspect of the story to tell.”

The mission itself is fairly routine—Koch and Meir are scheduled to swap out batteries on the station’s solar panels. Live video of the spacewalk (the 222nd spacewalk in history) will be available on NASA’s website.

A Huge Full Hunter’s Moon Will Light Up The Sky This Weekend

Chayanan/iStock via Getty Images
Chayanan/iStock via Getty Images

This weekend’s full moon will likely draw your eye even more than a regular one does.

Newsweek reports that what’s known as the full hunter’s moon—the first full moon after the harvest moon—will rise right around sunset, making it seem both much larger and more orange than usual. Though you’ll likely be able to spot it from Saturday, October 12 through the early morning hours of Tuesday, October 15, the best time to look up is Sunday night, October 13, when the moon reaches peak fullness.

According to The Old Farmer’s Almanac, the hunter’s moon may seem so huge because of a simple trick our eyes play on us called the “moon illusion.” Usually, when the moon is high and far from the horizon, it’s the main thing we see in the sky. Because the sky itself is so unfathomably vast, the moon looks pretty small. The hunter’s moon, however, appears lower in the sky, giving us a chance to view it next to things like trees and buildings. Since the moon is so much larger than those objects, our brains may process it with a better sense of scale.

The reason the hunter’s moon often glows orange is also related to its lower position. The moon is actually closer to us when it’s higher in the sky, so the light it reflects has to travel a shorter distance to reach our eyes, leaving the shorter wavelengths of blue light intact. When the moon is low, the air scatters those short blue wavelengths before they get to us, and only the longer, reddish wavelengths make it through.

Though we don’t know for sure why it’s called a hunter’s moon, The Old Farmer’s Almanac suggests that it may have once indicated the beginning of prime hunting season, when hunters could easily spot animals in fields that harvesters had just cleared after the previous month’s harvest moon.

And, after the hunter’s moon has come and gone, be sure to catch the full beaver moon in November.

[h/t Newsweek]

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