Unexplainable – "That's no moon..."

Podcast: Unexplainable (Vox)
Episode Date: December 1, 2025
Host: Bird Pinkerton
Guest: Dr. Nick Moskowitz, Lowell Observatory

Overview

This episode explores the mysterious object 2025 PN7, a small celestial body discovered near Earth and popularly (and sometimes confusingly) called a mini-moon, quasi-moon, or quasi-satellite. Host Bird Pinkerton and guest Dr. Nick Moskowitz delve into the science, terminology, and intrigue surrounding such objects—why we care about these cosmic neighbors, what they can teach us about the Earth, the Moon, and solar system history, and how advances in planetary exploration might change what we know.

Key Discussion Points & Insights

1. Naming the Mystery: What IS 2025 PN7?

• The discovery of 2025 PN7 led to lively public debate and terminological confusion: is it a second moon? A quasi-satellite? A mini-moon?
• According to Nick Moskowitz, the scientific community prefers the term "quasi-satellite" for PN7:

  “A term that most people in the community would agree on is a quasi-satellite.” — Nick Moskowitz (03:25)

2. Defining Near-Earth Objects and Quasi-Satellites (01:54 – 04:54)

• Near-Earth Objects (NEOs) are space objects that approach Earth—nearly 40,000 tracked so far.
• Quasi-satellites, unlike true moons, orbit the Sun but do so in a way that keeps them close to Earth for long periods.
• The conversation humorously references a viral QVC clip illustrating public confusion about what constitutes a planet, a moon, or a star:

  “When it comes down to it, it doesn't really matter what label you apply to these objects. They're doing interesting things that are rare and cool. And we geek out on that.” — Nick Moskowitz (04:27)

3. Classifying Space Objects Near Earth (06:03 – 08:12)

• First step: Determine if an object like PN7 is natural or human-made space junk. Human debris, such as defunct satellites and rocket stages, often lingers in Earth’s vicinity.
• Once natural status is established, scientists consider whether the object is:
  • Moon debris (ejected fragments from impact craters)
  • An asteroid
• Potential to trace moon fragments back to specific lunar craters could validate models of our moon's history.

4. Asteroids as Solar System Time Capsules (08:12 – 14:09)

• PN7 is most likely an asteroid, formed around the Sun 4.5 billion years ago, now temporarily orbiting near Earth.
• Asteroids, unmodified by Earth's tectonic or weathering processes, preserve the "original pots of modeling clay" from which the solar system formed:

  “There’s no wind on asteroids. There's no rain. There's no plate tectonics. There's none of the things that produce all the rocks that we see here on the surface of the Earth...” — Nick Moskowitz (12:50)

5. Asteroids, Meteorites, and Scientific Value (13:36 – 16:16)

• Occasionally, asteroids deliver meteorites (“nature's version of a sample return mission”) to Earth.
• Meteorites, which are physically analyzable, often lack context about their origin, while asteroids observed in space have more contextual data but are harder to study in detail.

  “A meteorite is like a free sample delivery courtesy of the universe.” — Bird Pinkerton (14:45)

6. Why Quasi-Satellites are Especially Exciting (15:44 – 17:35)

• Quasi-satellites are close, accessible, and their orbits can be well-characterized, offering a hybrid scientific value between meteorites and distant asteroids.
• Studying them may help link meteorite chemistry to specific parent bodies in the solar system, deepening our understanding of solar system evolution.

7. Future Prospects: Exploration, Resources, and Missions (16:59 – 19:36)

• Asteroids (including quasi-satellites) are considered as potential resources for material harvesting or spacecraft refueling (“in situ resource utilization”).
• Sample return missions like NASA's OSIRIS-REx and Japanese Hayabusa missions have brought back asteroid materials; China plans to target quasi-satellites specifically.

  “We'll be able to get that particular target we think is one of the lunar ejecta things. But we'll find out hopefully when the spacecraft gets there…” — Nick Moskowitz (18:08)

8. The Big Takeaway (19:36 – End)

• Rather than fixating on labels (“second moon”, “quasi-satellite”), the episode argues for wonder at these tiny cosmic neighbors—natural archives of the solar system’s earliest days, right in Earth's backyard.

  “We should talk about how cool it is that we have essentially tiny time capsules for neighbors, just like little archives of our solar system that are out there to be explored.” — Bird Pinkerton (19:36)

Notable Quotes & Memorable Moments

• Bird Pinkerton, reflecting on the naming debate:

  “You can call objects like this whatever you want. PN7, quasi-moon, quasi-satellite. Just don’t call them uninteresting.” (04:54)

• On space junk:

  “We're not good at cleaning up after themselves here on Earth and definitely not in space. And pieces of space junk hang around the Earth moon system in a very similar way.” — Nick Moskowitz (06:03)

• On holding a meteorite:

  “You're holding these rocks, you're looking at it, and this thing is older than the Earth, right? It's literally the oldest thing you can put your hands on.” — Nick Moskowitz (14:56)

• On meteorites as free science:

  “A meteorite is like a free sample delivery courtesy of the universe.” — Bird Pinkerton (14:45)

Timestamps for Key Segments

• 01:54 — Introduction to quasi-satellites, Nick Moskowitz
• 03:32 — Defining “quasi-satellite”
• 06:03 — Differentiating between space junk, moon debris, and asteroids
• 08:12 — The value of asteroids as time capsules
• 13:36 — The journey and value of meteorites
• 16:16 — Why quasi-satellites fill a crucial scientific gap
• 16:59 — Asteroids as future resource stations (“ISRU”)
• 18:08 — Osiris-Rex and international asteroid missions
• 19:36 — Episode summary: labels matter less than the opportunity to explore and learn

Tone & Language

The episode blends accessible scientific explanation with humor and genuine wonder. Bird Pinkerton uses personal anecdotes ("the QVC moon clip") and approachable analogies ("pots of modeling clay") throughout, making the technical science engaging for a broad audience. Dr. Moskowitz is equally enthusiastic, blending friendly honesty (“I don’t know what that means”) with clear scientific context.

Final Thoughts

The episode makes a strong case for the excitement and importance of studying quasi-satellites. They aren't just curious, undefined chunks of rock—they're crucial tools for science and perhaps for future exploration, holding secrets from the solar system's formative years. Whether you’re a fan of cosmic mysteries or just someone who likes to know what’s floating in your planetary neighborhood, PN7—and objects like it—are more than worthy of our attention.