Astronomers discover tiny moon near Earth

Astronomers have known about it since last March 28, but it is now, with its existence scientifically confirmed, that it has been disclosed.. Earth has a new moon. We are not talking about the lunar phase in which the satellite is located between the Earth and the Sun, becoming invisible from our planet.. Named 2023 FW13, it measures about 15 meters, about the size of a city bus.. For us it is not bad, but this is nothing in the dimensions of the universe. 'Primordial crumbs' are how some astrophysicists define these cosmic minutiae that wander through space.

And in the space around the Earth there are many of these minutiae. What happens is that their size means that they have gone unnoticed until now. “They are very small objects, with a dark surface and lack their own light, they only reflect sunlight.. That's why it's very difficult to see them.. They are not seen until they are very close,” explains José María Madiedo, astrophysicist at the Institute of Astrophysics of Andalusia, of the Higher Council for Scientific Research, CSIC.

This despite the fact that FW13 has been with us since 100 BC, according to astrophysicists.. The development of new telescopes has made this task easier.. The new moon was detected by one of them, the powerful Pan-STARRS, located on the Hawaiian volcano Haleakala.

The size of 2023 FW13 meant that it was initially ignored by scientists, who thought it was one of thousands of pieces of space debris orbiting Earth.. Determined that, indeed, it is a celestial body, it has been included in the list of the Minor Planet Center of the International Astronomical Union, IAU.

The small dimensions of 2023 FW13 have made astronomers rethink some cosmic names. It seems too sensationalist to call a space object that is a simple rock a moon. So they have named it a quasi-moon.

Although due to its orbit, it should be called a quasi-satellite, because despite its proximity to the Earth, it is gravitationally linked to the Sun.. 2023 FW13 orbits at a distance of 2.57 million kilometers from us, while the Moon of all life is 0.38 million kilometers away. The distance for the force of Earth's gravity to capture a celestial body, the so-called Hill sphere, is 1.5 million kilometers.

Some of these objects have an orbit very similar to that of the Earth. At some moments, the relative speed of the object with respect to that of the Earth is very small and it is located in an area where the gravity of our planet predominates.. Then they become traveling companions, the Earth captures it and turns it into a quasi-moon. “This capture can be for a short time or become a permanent capture,” explains Madiedo.

Theories about its origin

It is risky to point out the origin of this space body. What astronomers are careful to make clear when talking about these and the new moons that appear, is that they do not constitute any danger, and it is unlikely that they will fall to our planet.

The Moon does not have this only sister. Both are part of a family of which it is not known how many there are, although indications indicate that it is a large family.. “Four quasi-moons have recently been discovered and it would not be strange if more appear. In the environment of our planet there are many similar rocks that could be trapped by our planet,” says Madiedo.

In 2016, astronomers discovered one of these unknown sisters of Selene. At 100 meters in diameter, they called it Kamo'oalewa, a traditional Hawaiian name much more evocative than the insipid 2023 FW13 discovered this year.. While it gives clues to its nature, it is loaded with poetry, as it means The Daughter Who Travels Alone.

Kamo'oalewa, 2023 FW13 and the other 'new' little sister moons of Artemis are the advance of those that will be discovered in the coming years, astronomers joyfully say. A scientific joy that, on the contrary, can cause concern for poets and lovers when it comes to choosing which moon to stay on.

Small dictionary of celestial bodies

Asteroid. Piece of rock of very variable dimensions caused by the collision of primitive celestial bodies. Most are located in the Asteroid Belt, between Mars and Jupiter.

Kite. Celestial body formed by particles of rock, ice and gases such as methane that orbit around the Sun and whose components sublimate forming a hair made of gases and dust.

Quasi-moon. Asteroid that orbits the Sun and is trapped by the Earth's gravity, orbiting around it.

Quasi-satellite. Asteroid that orbits the Sun and passes through the proximity of the Earth, without being captured by its gravitational field.

Meteor. Flash of light caused by space debris burning up in the atmosphere.

Meteoroid. Space fragment less than 50 meters in diameter from comets, asteroids and planets, which upon entering the atmosphere is heated and vaporized totally or partially.

Meteorite. Meteoroid that does not completely disintegrate upon entry into the atmosphere and part of it impacts in solid form on the Earth's surface.

satelite. Celestial body that revolves around a planet.