juliensimon/solar-system-moons

---
license: cc-by-4.0
pretty_name: "Solar System Moons"
language:
- en
description: "All 440 known natural satellites of planets and dwarf planets in the Solar System with orbital elements, physical parameters, and discovery data. Sourced from NASA JPL Solar System Dynamics."
task_categories:
- tabular-classification
- tabular-regression
tags:
- space
- moons
- planets
- solar-system
- planetary-science
- open-data
- natural-satellites
- orbital-mechanics
- jpl
- tabular-data
size_categories:
- n<1K
configs:
- config_name: default
data_files:
- split: train
path: data/solar_system_moons.parquet
default: true
---

# Solar System Moons

*Part of the [Planetary Science Datasets](https://huggingface.co/collections/juliensimon/planetary-science-datasets-68214dab0f1e965e6741fcd2) collection on Hugging Face.*

Every known natural satellite of planets and dwarf planets in the Solar System —
currently **440** moons spanning discovery years **1610** to **2025**.

## Dataset description

This dataset catalogs all recognized natural satellites orbiting the major planets
(Earth through Neptune) and the dwarf planet Pluto, as maintained by NASA's Jet
Propulsion Laboratory (JPL) Solar System Dynamics group. Each record combines
discovery circumstances, mean orbital elements, and — where available — physical
parameters (radius, density, gravitational parameter).

The dataset merges three authoritative JPL tables:
- **Discovery circumstances** — name, parent body, year, discoverer
- **Mean orbital elements** — semi-major axis, eccentricity, inclination, period
- **Physical parameters** — mean radius, GM, density (for 46 major moons)

## Quick stats

- **Saturn**: 285 moons
- **Jupiter**: 101 moons
- **Uranus**: 30 moons
- **Neptune**: 16 moons
- **Pluto**: 5 moons
- **Mars**: 2 moons
- **Earth**: 1 moons
- **439** moons with orbital elements
- **46** moons with measured radius
- **297** retrograde moons (inclination > 90°)
- Largest moon: **Ganymede** (Jupiter, radius 2,631.2 km)

## Schema

| Column | Type | Description |
|--------|------|-------------|
| `name` | string | IAU name or provisional designation |
| `parent_body` | string | Parent planet or dwarf planet |
| `iau_number` | string | IAU Roman numeral designation |
| `provisional_designation` | string | Survey designation (e.g. S/2003 J2) |
| `discovery_year` | int64 | Year of discovery |
| `discoverer` | string | Discoverer(s) or spacecraft mission |
| `group` | string | Dynamical group/family (e.g. Galilean, Himalia, Norse) |
| `semi_major_axis_km` | float64 | Mean semi-major axis (km) |
| `eccentricity` | float64 | Mean orbital eccentricity |
| `inclination_deg` | float64 | Mean orbital inclination (degrees) |
| `orbital_period_days` | float64 | Sidereal orbital period (days) |
| `arg_periapsis_deg` | float64 | Argument of periapsis (degrees) |
| `mean_anomaly_deg` | float64 | Mean anomaly at epoch (degrees) |
| `long_ascending_node_deg` | float64 | Longitude of ascending node (degrees) |
| `epoch` | string | Epoch of orbital elements (TDB) |
| `mean_radius_km` | float64 | Mean radius (km), major moons only |
| `diameter_km` | float64 | Mean diameter (km), derived from radius |
| `gm_km3s2` | float64 | Gravitational parameter GM (km³/s²) |
| `mean_density_gcm3` | float64 | Mean bulk density (g/cm³) |
| `is_retrograde` | bool | True if inclination > 90° |
| `jpl_code` | string | JPL numeric satellite identifier |

## Usage

```python
from datasets import load_dataset

ds = load_dataset("juliensimon/solar-system-moons", split="train")
df = ds.to_pandas()

# Moons per planet
print(df["parent_body"].value_counts())

# Galilean moons of Jupiter
galilean = df[df["group"] == "Galilean"]

# Retrograde irregular satellites
retro = df[df["is_retrograde"] == True].sort_values("orbital_period_days")

# Largest moons by radius
biggest = df.dropna(subset=["mean_radius_km"]).nlargest(10, "mean_radius_km")

# Recent discoveries (2020+)
recent = df[df["discovery_year"] >= 2020]
```

## Data sources

- [JPL SSD Satellite Discovery](https://ssd.jpl.nasa.gov/sats/discovery.html) — names, parents, discovery circumstances
- [JPL SSD Orbital Elements](https://ssd.jpl.nasa.gov/sats/elem/) — mean orbital elements
- [JPL SSD Physical Parameters](https://ssd.jpl.nasa.gov/sats/phys_par/) — radius, density, GM

## Related datasets

- [neo-close-approaches](https://huggingface.co/datasets/juliensimon/neo-close-approaches) — NEO close approaches from JPL CNEOS
- [exoplanets](https://huggingface.co/datasets/juliensimon/exoplanets) — NASA Exoplanet Archive
- [asteroid-orbits](https://huggingface.co/datasets/juliensimon/asteroid-orbits) — All asteroid orbital elements

## Pipeline

Source code: [juliensimon/space-datasets](https://github.com/juliensimon/space-datasets)

## Citation

```bibtex
@dataset{solar_system_moons,
author = {Simon, Julien},
title = {Solar System Moons},
year = {2026},
publisher = {Hugging Face},
url = {https://huggingface.co/datasets/juliensimon/solar-system-moons},
note = {Based on NASA/JPL Solar System Dynamics satellite data}
}
```

## License

[CC-BY-4.0](https://creativecommons.org/licenses/by/4.0/)