Record-holder
PSR B1257+12
First exoplanets ever confirmed (1992) — orbiting a pulsar, not a normal star.
- Planets
- 3
- Distance
- 1956.9 ly
- Host
- G-type
About PSR B1257+12
Discovery
In 1992 Aleksander Wolszczan and Dale Frail used the Arecibo radio telescope to detect tiny variations in the pulses of millisecond pulsar PSR B1257+12 — the first exoplanets ever confirmed, three years before 51 Pegasi b.
Why it matters
PSR B1257+12's planets are the strangest known: they orbit a neutron star formed in a supernova, meaning they either survived the explosion or — more likely — re-formed from fallback or companion-star debris.
Current research
Pulsar-timing remains the primary tool; long-baseline timing continues to refine masses and search for additional bodies, with no further confirmations to date.
Comparable to
Three rocky planets orbiting the ultra-dense corpse of a dead star — bathed in radiation instead of starlight.
System geometry
At a glance
- Hostname
- PSR B1257+12
- Spectral type
- G2V
- Distance
- 1956.9 ly · 600.00 pc
- Stellar mass
- 1.40 M☉
- Stellar radius
- —
- Luminosity
- —
- Effective temp
- —
- Confirmed planets
- 3
- Habitable zone
- Unknown
Top-down orbital diagram
Orbits to scale within this system. Dashed green = habitable-zone edges.
Planet positions are illustrative (evenly spaced in phase). For live motion see the 3D scene.
The planets
3 confirmed.
Rocky world
PSR B1257+12 b
- Orbit
- 0.190 AU
- Period
- 25.26 days
- Radius
- 0.34 R⊕
- Mass
- 0.02 M⊕
- Eq. temperature
- —
- Eccentricity
- 0.000
- Discovered
- 1994 · Pulsar Timing
Sub-Neptune
PSR B1257+12 c
- Orbit
- 0.360 AU
- Period
- 66.54 days
- Radius
- 1.91 R⊕
- Mass
- 4.30 M⊕
- Eq. temperature
- —
- Eccentricity
- 0.019
- Discovered
- 1992 · Pulsar Timing
Sub-Neptune
PSR B1257+12 d
- Orbit
- 0.460 AU
- Period
- 98.21 days
- Radius
- 1.80 R⊕
- Mass
- 3.90 M⊕
- Eq. temperature
- —
- Eccentricity
- 0.026
- Discovered
- 1992 · Pulsar Timing
Compared to our Solar System
Each row shows the closest Solar-System analog by radius (log-space). Earth is pinned at the bottom as the constant frame of reference.
| Planet | Radius (R⊕) | Mass (M⊕) | Orbit (AU) | Period (days) | Eq temp (K) | Solar analog |
|---|---|---|---|---|---|---|
| PSR B1257+12 b | 0.34 | 0.02 | 0.190 | 25.26 | — | Mercury |
| PSR B1257+12 c | 1.91 | 4.30 | 0.360 | 66.54 | — | Earth |
| PSR B1257+12 d | 1.80 | 3.90 | 0.460 | 98.21 | — | Earth |
| Earth (reference) | 1.00 | 1.00 | 1.000 | 365.25 | 255 | — |
Research status
◇ JWST observation status
No JWST programs are currently targeting planets in this system. The system may be observed in future cycles or by upcoming missions (Ariel, HWO, Roman).
Discovery timeline
- 1992
2 planets: c, d
via Pulsar Timing
- 1994
PSR B1257+12 b
via Pulsar Timing
If you liked this
Other systems in the same theme:
Kepler-16
1 planets · 244.9 ly · G2V
A real-world Tatooine — a planet orbiting two stars at once.
GJ 1132
2 planets · 41.1 ly · M4.5 V
A Venus analog 41 ly away — terrestrial world losing its atmosphere.
HD 189733
1 planets · 64.5 ly · K2 V
A blue planet — but the colour comes from glass rain in the upper atmosphere.
Experience it
See PSR B1257+12 in interactive 3D
Fly through the system, click any planet, watch orbits play out at 100× speed.
▶ Launch 3D scene