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A Tour of the Moon

Scientists are continuing to learn more about Earth’s closest neighbor.

May 12, 2025
By Nicole Tocco

As You Read, Think About: Would you want to visit the moon?

The Grand Canyon is one of the most amazing landmarks on Earth. It was carved out over millions of years by the Colorado River and other bodies of water. Did you know that the moon has canyons too? Two of them, Vallis Schrödinger and Vallis Planck, are located near the moon’s south pole. They’re deeper than the Grand Canyon—but may have been created in less than 10 minutes! A giant asteroid crashed into the moon 3.8 billion years ago. That collision sent rocky debris raining down on the lunar surface, leaving the two giant canyons behind.

Scientists used photos from NASA’s Lunar Reconnaissance Orbiter to determine how the two canyons formed. They released their findings in February. Researchers are studying the south pole because it’s the planned landing spot for the long-awaited return of astronauts to the moon. That could happen as soon as 2027. In the meantime, NASA and space agencies from other nations continue to explore different areas of the moon. Read on to learn more about Earth’s closest neighbor. 

Collision Course

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Scientists think the moon formed about 4.5 billion years ago, when a small planet crashed into the young Earth. Over time, dust and molten rock from the crash combined to form the rocky sphere that orbits our planet. 

Today the moon is covered with craters formed by asteroids and other space rocks. Most of those objects would burn up in Earth’s atmosphere. But the moon’s atmosphere is weak and thin, so it offers little protection.

Waterless Seas

Early astronomers thought the dark spots on the moon were bodies of water. These areas were given the name mare (MAHR-ay), or “sea.” We now know that they were blasted out by asteroid strikes more than 3 billion years ago. They were later filled with lava that flowed up from cracks in the moon’s crust and eventually hardened.

In 1969, NASA’s Apollo 11 spacecraft landed at the edge of one of these areas, the Sea of Tranquility. Astronauts Buzz Aldrin (below) and Neil Armstrong became the first people to walk on the moon. There’s no wind or rain on the moon, so their footprints are still visible.

NASA (Aldrin); Heritage Space/Heritage Images via Getty Images (footprint)

Astronaut Buzz Aldrin’s footprint

Mapping the Moon

NASA/GSFC

After Apollo 11, 10 more U.S. astronauts landed on the moon. No one has been back since 1972. But spacecraft like the Lunar Reconnaissance Orbiter (right) help scientists continue to study the moon. The orbiter has been mapping the moon since 2009. 

Data collected by the orbiter has enabled researchers to make new discoveries. Last year, a team of scientists announced that they had found a long cave connected to a deep pit on the moon’s surface. The area could be the site of a future base or emergency shelter for astronauts. 

The Far Side

NASA/GSFC/Arizona State University

On Earth, we only ever see one side of the moon: the near side. The far side (right) has even more craters but fewer dark seas than the near side. In 2019, China became the first country to land a spacecraft on the moon’s hidden side. Last year, a Chinese probe returned to Earth with the first samples ever taken from the far side. Scientists hope the samples will give new clues about how the moon formed.

1. Based on the article, why are many researchers focusing their attention on the moon’s south pole?

2. How has scientists’ understanding of the moon’s dark spots changed over time?

3. How has the Lunar Reconnaissance Orbiter helped scientists learn about the moon?

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