How many moons does Earth have?

Our planet currently has only one moon. This natural satellite is even named the Moon.

In the early days of human exploration of the stars, we only knew the Moon as a single natural satellite. But with the development of science , we gradually discovered many more natural satellites in the Solar System that are similar to or much larger than Earth's Moon.

According to Live Science , based on the definition of a natural satellite, Earth may have had more than one moon in the past and present.

Earth has more "moons" than we think. (Image: HowStuffWorks)

According to astronomer Gábor Horváth of Eötvös Loránd University (Hungary), the Moon remains Earth's only solid-state artificial moon. However, the Moon is not the only object orbiting Earth; there are also dust clouds revolving around our planet. By definition, these dust clouds are considered micromoons, semi-satellites, or "ghost moons."

Therefore, the question of how many moons Earth has is more complex than we think. The number has changed over time – from 0, to one, and sometimes to many moons.

Going back to the early days of Earth, about 4.5 billion years ago, our planet had no moons. Then, about 4.4 billion years ago, a protoplanet nearly the size of Mars called Theia collided with Earth. Huge chunks of rocky material from our planet were ejected into space, becoming the "foundation" for the formation of natural satellites.

These fragments of rock and soil then combined within hours or so and gradually formed the Moon as we know it today.

Currently, besides the Moon, Earth also has "mini-moons" with diameters ranging from just a few centimeters to several meters, which are pulled into the planet's orbit by gravity, but only for a short time.

A prime example is the 2006 asteroid 2006 RH120, measuring 6 meters in length, which orbited Earth for a record-breaking 18 months before drifting further into space. More recently, there's the case of the 3.5-meter-long asteroid 2020 CD3, which orbited Earth for three years – essentially a second moon for our planet.

In addition to natural satellites that come and go from Earth's orbit, there are also space objects that NASA calls quasars, such as asteroid 3753 Cruithne. These space rocks orbit the Sun so closely, like Earth, that they bond with our planet for its entire 365-day orbit.

Earth has many natural satellites that come and go from orbit, and they orbit our planet much like the Moon.

Some space objects, such as asteroid 2010 TK7, are also called "moons" because they are pulled into orbit by the gravitational forces of the Sun-Earth or Earth-Moon.

According to Horváth, parallel to the formation of the solid moon and the stabilization of its orbit around Earth, Lagrange points also appeared—gravitational pull that held interplanetary dust particles around our planet for billions of years. (Lagrange points are the gravitational forces of two larger objects creating regions of centripetal force.)

Some astronomers call these particle clouds "ghost moons" or Kordylewski clouds, named after the Polish astronomer who discovered them in the 1960s.

However, these “ghost moons” will never form a solid moon because the dust cannot coalesce, bond, or stick together, Horváth said. Meanwhile, Lagrange points remain constant; the material within them is constantly moving in and out of the dust cloud.

Tra Khanh (Source: Live Science)

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Source: https://vtc.vn/trai-dat-co-bao-nhieu-mat-trang-ar759777.html