Interesting facts about the Moon, from its birth to Chandrayaan

The Moon is Earth's only natural satellite and the brightest object in the night sky. From poems, festivals and calendars to the tides of the sea, the Moon is everywhere in our lives. Here are interesting facts about the Moon — from its birth to India's Chandrayaan.

The Moon at a glance

How did the Moon form?

The idea most accepted by scientists is the "giant impact". About 4.5 billion years ago, when Earth was newly formed, a Mars-sized body — named "Theia" — crashed into it. The debris thrown out by the collision kept circling Earth, gradually stuck together and became the Moon. Moon rocks brought back by the Apollo missions are very similar in make-up to Earth's rocks, which supports this idea.

Why do we always see the same side of the Moon?

The Moon takes exactly as long to turn once on its axis as it takes to go once round Earth — about 27.3 days. This is called "synchronous rotation". That is why from Earth we always see the same face of the Moon. The other side was first seen in 1959, in pictures from the Soviet craft Luna 3. It is sometimes called "the dark side of the Moon", but it gets just as much sunlight — we simply cannot see it.

Did you know? The Moon is moving away from Earth by about 3.8 centimetres every year. We know this because the Apollo astronauts left special mirrors on the Moon, and lasers fired at them from Earth measure its distance very precisely.

The Moon and Earth

• Tides: the Moon's gravity pulls the sea's water towards it, causing high tide and low tide about twice a day each. At full moon and new moon the Sun and the Moon are in a line, and then the tides are highest.
• Phases: the Moon does not shine by its own light; it reflects sunlight. How much of its lit side we see as it goes round Earth creates phases such as the new moon, the half moon and the full moon.
• Calendar: the months and tithis of the Indian panchang are based on the Moon's phases, which is why the dates of Diwali, Eid and many festivals change every year in the English calendar.
• Keeping Earth steady: the Moon helps keep the tilt of Earth's axis fairly stable, so the seasons do not swing too wildly.

Humans on the Moon, and India

On 20 July 1969 Neil Armstrong of the Apollo 11 mission became the first person to step on the Moon, followed by Buzz Aldrin. Between 1969 and 1972 a total of 12 people walked on the Moon. Because there is no air or water there, their footprints are probably still almost as they were. On the Moon the temperature rises above 100 °C by day and falls below −150 °C at night.

India's Chandrayaan-1 (2008) helped find evidence of water molecules on the Moon, and on 23 August 2023 Chandrayaan-3 landed near the south pole — the full story: Chandrayaan-3. The hide-and-seek between the Moon and the Sun: How eclipses happen.

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