# How exoplanets were discovered

- Snapshot: 12 October 2026.
- exoplanets.csv: one row per confirmed planet; four original archive fields.
- chart-data.csv: the five groups plotted in the chart.
- render.py: offline Python/Pillow renderer. Run `python render.py` after installing requirements. Use DejaVu Sans fonts; set CHART_FONT_DIR if installed elsewhere.

## Fields
- pl_name: planet name.
- discoverymethod: discovery technique recorded by the archive.
- disc_year: recorded discovery year.
- disc_facility: discovery facility.
- discovery_group: displayed group; Radial Velocity becomes Stellar wobble, Imaging becomes Direct imaging, and seven smaller methods become Other methods.
- planet_count: count in the group.
- share_percent: group count divided by 6,445, times 100.

The chart describes discovery methods, not whether a planet was imaged subsequently. The snapshot contains 6,445 unique planets, including 97 discovered by imaging.

## Source and acknowledgement
Data: NASA Exoplanet Archive, operated by Caltech under contract with NASA through the Exoplanet Exploration Program.
https://exoplanetarchive.ipac.caltech.edu/
Archive acknowledgement and citation guidance: https://exoplanetarchive.ipac.caltech.edu/docs/acknowledge.html
Archive overview: https://exoplanetarchive.ipac.caltech.edu/docs/intro.html

This package uses the public downloadable catalog's factual fields. It does not include survey images, light curves, papers or third-party artwork, and does not assert a blanket CC0 licence for archive holdings. Retain the archive acknowledgement when reusing this extract and cite the archive's current overview paper, Christiansen et al. (2025), linked from its acknowledgement page.

TAP endpoint: https://exoplanetarchive.ipac.caltech.edu/TAP/sync
Query: select pl_name,discoverymethod,disc_year,disc_facility from ps where default_flag=1
Format: csv

## Preparation and checks
Selected the archive's default planet records (default_flag=1) and the four
original fields named above. The CSV has 6,445 records and 6,445 distinct planet
names. No duplicate records were removed and no source errors were corrected.
Discovery years in this snapshot run from 1992 to 2026.

For chart-data.csv, Transit and Microlensing keep their original names; Radial
Velocity is labelled Stellar wobble and Imaging is labelled Direct imaging.
Other methods combines Eclipse Timing Variations, Transit Timing Variations,
Orbital Brightness Modulation, Pulsar Timing, Astrometry, Disk Kinematics and
Pulsation Timing Variations. Counts reconcile to the planet CSV; share_percent
is count / 6,445 * 100, saved to ten decimal places. Display labels round to one.

Archive acknowledgement: This research has made use of the NASA Exoplanet
Archive, which is operated by the California Institute of Technology, under
contract with the National Aeronautics and Space Administration under the
Exoplanet Exploration Program.

Archive overview reference: Christiansen et al. (2025), The Planetary Science
Journal, https://doi.org/10.3847/PSJ/ade3c2 . Cite original literature separately
when using results from a specific paper. This extract does not include those
papers or their reference fields. Public catalog acknowledgement is retained;
no CC0 licence is assigned to NASA Exoplanet Archive data.