Astronomers have found a small object travelling near Earth in its orbit around the Sun for the last 6 decades, we are talking about the 2025 PN7. Even though it has remained near all this time, telescopes detect this object very recently, which is why some scientists call it the ‘’invisible moon’’.

This finding reminds us that space is full of surprises, even near Earth, there are still hidden objects that we are barely starting to discover them. So, let’s learn more about this discovery.

2025 PN7

This is a quasi-moon, which means that it follows a similar trajectory to the one of our planet around the Sun, but it’s not gravitationally linked as the real moon is. Its size is about 98 feet, which explains why it was unnoticed until now. Such a small object is very difficult to detect in the vast space and it only becomes visible when it’s near Earth.

The 2025 PN7 belongs to the Arjuna secondary asteroid belt, a group of rocks that have very similar orbits to Earth’s. The first of these was discovered in 1991 and at that moment some thought it could be an interstellar probe. Thirty years later, the scientific community agrees that they are natural rocks from space.

Quasi-moons and mini-moons

The 2025 PN7 discovery helps understand the difference between quasi-moons and mini-moons, so let’s see the difference:

  • Quasi-moons share Earth’s orbit around the Sun in what scientists call a “1:1 resonance.” They move alongside Earth, but they are not true satellites because they are not held by Earth’s gravity.
  • Mini-moons, in contrast, are temporarily captured by Earth’s gravitational pull. They orbit the planet for a few weeks or months before escaping back into space.

A recent example was the 2024 PT5, which became an Earth’s mini-moon for a short period of time between September and November of 2024.

Could these pieces come from the moon?

Some astronomers believe that quasi-moons like the 2025 PN7 aren’t random asteroids, they were ancient pieces of Earth’s Moon. These pieces would have been released a long time ago after strong impacts and, since then, scientists have tracked trajectories near our planet.

Other examples are Kamo’oalewa and 2024 PT5, whose behavior and composition suggest a common origin with the Moon because they offer valuable clues about Earth’s history and its natural satellite.

How long will it stay with us?

Researchers estimate the 2025 PN7 will accompany Earth in its orbit around the Sun for about 60 years more! Then, it will go far toward the horseshoe orbit around the Sun.

This type of orbit looks like a giant horseshoe when plotted from Earth’s perspective, as the object seems to loop around and swap positions relative to our planet. Importantly, scientists say that 2025 PN7 does not pose any threat to Earth. It is simply a silent companion, moving through space with us.

Invisible for a long time

The main reason is its small size. With barely 30 meters of diameter it reflects very little light, which makes it almost invisible for terrestrial telescopes if it’s not near our planet.

This finding proves there’s still a long way to go to discover what’s hidden in our cosmic neighborhood. More than 100 quasi-moons have been detected in similar orbits, but there are probably more waiting to be observed.

A reminder of Earth’s place in space

2025 PN7’s story proves that our planet doesn’t travel alone around the Sun. Apart from the Moon, there are small temporary partners that share our path. Some stay for decades, like the 2025 PN7, and others become mini-moons for just a few months.

Each new finding helps scientists to better understand how Earth interacts with its surroundings and how pieces of our own Moon can be still near. Don’t you think space is one of the most fascinating things about life? We never stop learning new things about it and they are all fascinating.