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The Moon is the celestial body closest to Earth in the universe. The average distance between the Moon and Earth is 384,400 km. If a person were to walk from Earth to the Moon, it would take about 9 years. By spacecraft, the journey from Earth to the Moon takes over 7 days.
The Moon’s orbital period around Earth is 27.32 days, and the distance from Earth to the Moon is 384,000 km. However, scientists have discovered that the Moon is moving away from Earth at a rate of 3.8 cm per year. This number is relatively small and cannot be perceived with the naked eye.
At this rate, over the past 10,000 years, the Moon has moved 380 meters away from Earth. Consequently, it will take around 5 billion more years for the Moon to be 200,000 km farther. Nevertheless, even then, the Moon will remain in Earth’s orbit, but with a different cycle than it has today.
In 5 billion years, the Sun will enter a phase of expanding its outer layers, becoming a massive red giant that will likely engulf Venus, Mercury, Earth, and even the Moon. This time span is far beyond a human lifetime, so there’s no need for concern.
One question arises: why is the Moon moving farther away from Earth? The reason is that while the Moon orbits Earth, it is tidally locked with our planet. Therefore, the Moon’s orbital cycle synchronizes with its rotation cycle, ensuring that one side of the Moon always faces Earth.
Due to the gravitational interaction between the Moon and Earth, both experience tidal bulges toward each other. However, Earth’s rotation period is shorter than the Moon’s, causing the bulge created by the Moon on Earth’s surface to continually shift. This phenomenon accelerates Earth’s rotation compared to the Moon’s orbital motion.
The Moon’s gravitational pull slows down Earth’s rotation, reducing its rotational energy. This energy is then transferred directly, causing the Moon to spin faster. Consequently, the Moon’s self-propelled motion is gradually moving it farther away, in accordance with the law of acceleration.
The Moon is a satellite that orbits Earth, devoid of heat and light emission. It is the only celestial body apart from Earth that humans have set foot upon.
The year 1959 was a historic year for lunar exploration, marked by the launch of the artificial satellite Luna 1 by the Soviet Union, which reached the vicinity of the Moon. Subsequently, Luna 2 crashed onto the Moon’s surface, and Luna 3 provided the first images of the far side of the Moon.
In 1966, Luna 9 became the first spacecraft to successfully land on the Moon, followed by Luna 10, the first unmanned spacecraft to orbit the Moon. Currently, the craters near the lunar south pole are the coldest spots in the Solar System.