Earth may only have one true moon, but astronomers have also discovered a number of so-called ‘quasi-moons’ in our neighborhood. Here’s what to know about them.
Recently, the online world has been abuzz with speculation that NASA has confirmed the discovery of a second moon in Earth’s orbit.
Take any such rumors with a hefty grain of salt.
Earth still only has one true natural satellite – our 2,159-mile-wide moon located about 239,000 miles away. However, astronomers have discovered a number of celestial objects over the years in our cosmic neighborhood that they’ve deemed “quasi-moons.”
That includes the recently spotted asteroid 2025 PN7, which appears to be the source of the rumor mill about Earth’s supposed second moon.
Here’s everything to know about the asteroid and why it’s called a quasi-moon.
Does Earth have 2 moons? What to know about the ‘quasi-moon’
Not quite.
But, something called a “quasi-moon” was discovered in August that gave rise to the recent ramped-up notion that Earth has a second moon.
The Pan-STARRS observatory in Hawaii was the first to spot the quasi-moon in question. The object was then reported to the Minor Planet Center – the official authority for observing and reporting new asteroids, comets and other small bodies in the solar system – and given the name 2025 PN7.
Earth has several quasi-moons that get their name because they exhibit behavior resembling our actual moon – including that they appear to orbit our planet, according to the nonprofit The Planetary Society. But the objects in question are not only just asteroids, but also instead orbit the sun, following an almost exact path as Earth while always remaining close by.
What is asteroid 2025 PN7? Is it dangerous?
Astronomers say that asteroid 2025 PN7 poses no danger to Earth.
The asteroid is dim and small – about 62 feet in diamater – which is why it managed to evade detection for so many years.
The space rock, also outlined in a recent study published by the American Astronomical Society, is believed to have been in this Earth-adjacent orbit for about 60 years, according to the website EarthSky. Asteroid 2025 PN7 is also expected to remain our neighbor for another six decades before the sun tugs it away.
Earth also had ‘mini-moon’ in 2024. What’s the difference?
A chunk of space rock that visited near Earth’s orbit in 2024 was widely referred to as a “mini-moon.”
The small rock, known as 2024 PT5, captured the world’s attention when it came close enough to Earth between September and November to be classified as a near-Earth object. While the asteroid never posed a threat to our planet, it did intrigue astronomers, who rushed to study it before it bid farewell and continued on its way.
So, what makes a “mini-moon” different from a “quasi-moon?” While quasi-moons are a permanent celestial neighbor, mini-moons are simply temporary visitors, according to The Planetary Society.
Because they are small and hard to detect, just four have ever been discovered – none of which are still orbiting Earth.
In a bit of serendipity, astronomers determined that the mini-moon discovered in 2024 may have actually earned its lunar-inspired nickname, as it may have been a moon rock ejected into space.
Eric Lagatta is the Space Connect reporter for the USA TODAY Network. Reach him at elagatta@gannett.com