juliensimon/nesvorny-asteroid-families

---
license: cc-by-4.0
pretty_name: "Nesvorny Asteroid Families (HCM V2.0)"
language:
- en
description: "170,981 asteroids grouped into 265 dynamical families identified by hierarchical clustering (Nesvorny et al. 2015, 2024). Essential for asteroid collisional history and solar system evolution studies."
task_categories:
- tabular-classification
- tabular-regression
tags:
- space
- asteroids
- families
- collisions
- orbital-mechanics
- open-data
- tabular-data
size_categories:
- 100K<n<1M
configs:
- config_name: default
data_files:
- split: train
path: data/nesvorny_asteroid_families.parquet
default: true
---

# Nesvorny Asteroid Families (HCM V2.0)

*Part of the [Orbital Mechanics Datasets](https://huggingface.co/collections/juliensimon/orbital-mechanics-datasets-68047314acba552840224498) collection on Hugging Face.*

**170,981** asteroids grouped into **265** dynamical families from the
Nesvorny HCM (Hierarchical Clustering Method) catalog. Asteroid families are groups
of bodies sharing similar orbits, identified as fragments from catastrophic collisions
in the asteroid belt.

## Dataset description

This dataset combines the original 2015 family identifications (105 families, 143,711
members) with 153 newly discovered families from the 2024 update (27,270 members),
based on proper orbital elements for 1.25 million main-belt asteroids. The hierarchical
clustering method groups asteroids by proximity in proper element space (semimajor axis,
eccentricity, inclination), revealing the collisional history of the solar system.

Families span the entire asteroid belt: inner belt (Flora, Vesta), middle belt (Eunomia,
Koronis), outer belt (Themis, Eos, Hygiea), plus Hilda, Hungaria, Phocaea, and
high-inclination populations.

## Schema

| Column | Type | Description |
|--------|------|-------------|
| `asteroid_number` | Int64 | MPC asteroid number (nullable for unnumbered objects) |
| `proper_a_au` | float64 | Proper semimajor axis (AU) |
| `proper_e` | float64 | Proper eccentricity |
| `sin_i` | float64 | Sine of proper inclination |
| `abs_mag` | float64 | Absolute magnitude H (mag) |
| `c_param` | float64 | Interloper identification parameter (2015 families only) |
| `freq_g_arcsec_yr` | float64 | Proper frequency of pericenter longitude (arcsec/yr, 2024 only) |
| `freq_s_arcsec_yr` | float64 | Proper frequency of nodal longitude (arcsec/yr, 2024 only) |
| `n_oppositions` | Int64 | Number of observed oppositions from MPC (2024 only) |
| `packed_name` | string | MPC packed designation (2024 only) |
| `unpacked_name` | string | MPC unpacked name/designation (2024 only) |
| `family_number` | Int64 | Family ID from Nesvorny catalog |
| `family_name` | string | Family name (named after largest member) |
| `region` | string | Belt region (inner, middle, outer, hilda_hungaria, highinclination, phocaea) |
| `source` | string | Catalog version: "2015" or "2024" |

## Quick stats

- **170,981** asteroid-family memberships across **265** families
- 143,711 from 2015 catalog, 27,270 from 2024 catalog
- 153,795 with numbered asteroid IDs
- Proper semimajor axis range: 1.8399 -- 5.3347 AU

## Usage

```python
from datasets import load_dataset

ds = load_dataset("juliensimon/nesvorny-asteroid-families", split="train")
df = ds.to_pandas()

# Largest families
top = df.groupby("family_name").size().sort_values(ascending=False).head(10)
print(top)

# Plot families in proper element space
import matplotlib.pyplot as plt
fig, ax = plt.subplots(figsize=(12, 6))
for name, grp in df.groupby("family_name"):
if len(grp) > 1000:
ax.scatter(grp["proper_a_au"], grp["sin_i"], s=0.1, alpha=0.3, label=name)
ax.set_xlabel("Proper semimajor axis (AU)")
ax.set_ylabel("sin(i)")
ax.legend(markerscale=20, fontsize=8)
plt.title("Major Asteroid Families in Proper Element Space")
plt.show()
```

## Data source

Nesvorny, D. (2024), *Nesvorny HCM Asteroid Families V2.0*,
NASA Planetary Data System, urn:nasa:pds:ast.nesvorny.families::2.0.
[PDS SBN Archive](https://sbn.psi.edu/pds/resource/nesvornyfam.html)

Based on: Nesvorny, D., Broz, M., Carruba, V. (2015), *Identification and Dynamical
Properties of Asteroid Families*, in Asteroids IV, 297-321.

## Pipeline

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

## Citation

```bibtex
@dataset{nesvorny_asteroid_families,
author = {Simon, Julien},
title = {Nesvorny Asteroid Families (HCM V2.0)},
year = {2026},
publisher = {Hugging Face},
url = {https://huggingface.co/datasets/juliensimon/nesvorny-asteroid-families},
note = {Based on Nesvorny (2024) via NASA PDS Small Bodies Node}
}
```

## License

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