Yet something small, steady and near has joined our daily journey.
NASA has signed off on a new tag‑along to Earth’s path around the Sun, a quasi‑moon called 2025 PN7. It is not a second Moon in the strict sense, yet it shares our year, lingers in our neighbourhood, and will keep time with us until 2083 before slipping away again.
What NASA actually confirmed
The object, discovered by a University of Hawaii survey team, matches Earth’s orbital pace so closely that it appears to shadow our planet. Astronomers call this arrangement a quasi‑satellite. The rock orbits the Sun, not Earth, but it stays near us thanks to a delicate balance of gravity and timing.
Observations suggest 2025 PN7 measures roughly 18 to 36 metres across, the size of a small building. That makes it tiny by asteroid standards, but intriguing. It sits far beyond the reach of our tides and far beyond any danger to spacecraft in Earth orbit.
NASA confirms 2025 PN7 as a quasi‑moon that tracks Earth’s year, drifting between about 4 and 17 million kilometres before departing around 2083.
How big, how far, how faint
Quasi‑moons do not cruise beside us at the distance of the Moon. They trace wide loops that, from our frame of reference, look like a slow‑motion, kidney‑shaped dance around Earth.
| Parameter | Value | What it means |
|---|---|---|
| Designation | 2025 PN7 | Asteroid confirmed as an Earth quasi‑satellite |
| Estimated size | 18–36 metres | Comparable to a small building; far smaller than the Moon |
| Distance range | 4–17 million kilometres | About 10–44 times farther away than the Moon |
| Companionship | Now to ~2083 | Stays in step for decades, then drifts off |
| Discovery | University of Hawaii survey | Spotted during routine near‑Earth object scanning |
| Population | One of about eight known quasi‑moons | A small, select group of Earth companions |
That distance matters for visibility. Even at its nearest, 2025 PN7 glows far below naked‑eye limits. Amateur telescopes will not pick it out. Professional facilities caught it as a faint point drifting slowly against the background stars, moving just enough to betray its Earth‑like year.
What makes a quasi‑moon different from a moon
Earth’s true Moon is gravitationally bound to our planet and orbits us every 27.3 days. A quasi‑moon orbits the Sun. It sits in a 1:1 resonance with Earth’s year, so it keeps pace while the Sun’s pull dominates. In a rotating view that moves with Earth, the object seems to loop around us. In real space, it follows its own solar path.
This arrangement depends on small nudges from the Sun and nearby planets. Those tugs shift the asteroid’s shape of motion over decades. The result is a long companionship that ends when those tiny forces tip the balance and the rock’s path drifts out of phase.
Not a second Moon, not a threat: a co‑orbital neighbour sharing our year, governed mainly by the Sun and time.
Why scientists care
Quasi‑moons sharpen our models of near‑Earth space. They reveal how small bodies behave under the combined pull of the Sun, Earth and other planets. That improves risk forecasts for future asteroid encounters and refines spacecraft navigation in this complex gravitational field.
Mission opportunities within reach
Their proximity creates practical advantages for technology testing and science. Engineers can send compact probes to a quasi‑moon with modest fuel and shorter flight times compared with many deep‑space targets.
- Low‑cost fly‑bys to trial guidance, navigation and control systems.
- Surface composition studies using small impactors or remote sensing.
- Radio and laser ranging experiments to validate tracking and communications.
- Sampling rehearsals ahead of larger asteroid‑defence or resource missions.
Because 2025 PN7 is small, it offers clean measurements of subtle forces like solar radiation pressure and the Yarkovsky effect, a minute thermal push that can shift an asteroid’s course over years. Those details feed back into better long‑term predictions for other near‑Earth objects.
Will you notice a second moon?
No. The object is too faint for the eye and much farther away than the Moon. It creates no tides, no extra night‑time glow and no changes to calendars or eclipses. While headlines speak to “two moons”, the science points to a quieter reality: a swift stone keeping time with us, unnoticed from the ground.
Your satellite TV, your phone navigation and the International Space Station remain unaffected. Earth’s immediate orbital lanes sit tens of thousands of kilometres from the surface; 2025 PN7 stays millions of kilometres away.
The road to 2083: why it stays, why it leaves
Gravity from the Sun anchors 2025 PN7, while Earth adds a small tug that locks the rock into a near‑match of our orbital period. Jupiter and Venus add their own whispers. Over roughly six decades of companionship so far, those pulls have kept the asteroid in step. By the 2080s, the slow accumulation of these nudges should pull it out of rhythm and send it wandering.
That estimate rests on weeks of tracking data tied into decades of celestial mechanics. As astronomers gather more observations, they will tighten the timing and map possible departure windows. The broad picture holds: this partnership began decades ago and should fade in the second half of this century.
The small club of Earth’s co‑orbitals
A handful of other rocks have shared our year. Some stayed for years, some for centuries. Each arrival adds a datapoint to a sparse record. With only about eight confirmed quasi‑moons to date, 2025 PN7 lands in rare company and gives researchers a fresh case study in co‑orbital dynamics.
What this means for you
Think of 2025 PN7 as a lesson in how crowded our near‑Solar space can be and how carefully we monitor it. If you use a planetarium app, set Earth as the centre and watch a simulation of a quasi‑satellite path. The motion looks like a lazy loop around Earth that reverses direction through the year. That shape captures the idea better than any single diagram.
Teachers can turn this story into a quick activity. Compare a true lunar orbit with a quasi‑satellite loop in a rotating frame. Then ask pupils to predict what happens as the object slides outward to 17 million kilometres and back to 4 million kilometres. The exercise shows how a simple resonance can lock two bodies into a long companionship without a direct orbit.
For those tracking risk, the message is calm. The rock is small. It stays far away. It follows a path dominated by the Sun. No effect on tides, weather or earthquakes. The gain sits on the science side: better models, sharper forecasts and a target close enough to visit when the next small mission needs a proving ground.
If you feel tempted to look up for a second Moon, look instead for the familiar. The real Moon still rules the night. The newcomer moves quietly, a distant fellow traveller that tells us more about the space we share than about any change to life on Earth.
Two moons? Not really—it’s a quasi‑moon.
A tiny co‑orbital buddy at 4–17 million km—space is wild! 🙂 Any chance of a small cubesat flyby before 2083 to test navigation and Yarkovsky measurements?