Astronomers Have Found Earth’s Newest Quasilunar Moon

The Earth has simply added its seventh confirmed quasilunar moon. It is 2025 PN7, a small Apollo-type asteroid detected in August solely by its brightness, due to the Hawaiian Pan-STARRS 1 telescope.

After analyzing its trajectory, scientists concluded that the article maintains a 1:1 resonance with the Earth. In different phrases, it orbits the solar similtaneously our planet. From a distant perspective, this synchronicity makes it look as if the Earth is accompanied by a tiny asteroid—as if it had an extra moon.

Unlike the moon, quasilunar moons are usually not gravitationally bound to the Earth. They are ephemeral companions, in cosmological phrases, following their very own path across the solar. Only at sure occasions do they arrive shut sufficient to seem sure. In the case of 2025 PN7, its minimal distance is 299,000 km, whereas at its farthest level it might probably attain 17 million km. For comparability, the moon stays at a median distance of 384,000 km from Earth.

According to the article printed in Research Notes of the AAS, the asteroid has been in a quasi-satellite part since 1965, and is anticipated to stay so for 128 years. Some researchers estimate that 2025 PN7 will lastly transfer away in 2083.

Why Does the Earth Have Quasilunar Moons?

So far, seven our bodies have been confirmed that seem to accompany the planet in its orbit. Astronomers consider that extra could also be found sooner or later. Earth is a pure reservoir of quasilunars as a result of the Earth’s orbit is just like that of sure close by objects that inhabit the so-called Arjuna group of asteroids, a inhabitants that has solely lately begun to be studied in higher element.

The Arjuna group doesn’t type a hoop just like the asteroid belt between Mars and Jupiter, however contains a legion of near-Earth rocks that orbit the solar on the same path as our planet. Occasionally, a few of these asteroids coincide with our trajectory and, relying on their orbital dynamics, are categorized as quasilunar or mini-moons.

The quasilunar moon 2025 PN7 sits within the Arjuna asteroid group not removed from Earth.Illustration: WIRED