Halley
1P/Halley
Where is it now
- Distance from Sun
- 35.175 AU
- True anomaly
- 180.82°
- As of
- 17 September 2026
Two-body Kepler propagation — accurate to ~0.1% for major planets over decades, less so for highly-perturbed bodies. Use JPL Horizons for high precision.
In the sky
- Right ascension
- 08h 18m 57s
- Declination
- +03° 06′ 56″
- Constellation
- Hydra
- Distance from Earth
- 35.8 AU
- Elongation from the Sun
- 51.17° — near the Sun — look low at dusk or dawn
Visible from both hemispheres.
From your location
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Two-body approximation, good to about a degree for the planets — enough to find the constellation and know whether it is up.
Orbital elements
- Semi-major axis
- 17.929 AU
- Eccentricity
- 0.9679
- Inclination
- 162.19°
- Orbital period
- 75.92 years
- Perihelion
- 0.575 AU
- Aphelion
- 35.282 AU
- Longitude of ascending node
- 59.1°
- Argument of periapsis
- 112.24°
- Epoch · J2000
- 2439875.5
- Orbit class · HTC
- Halley-type comet
- Earth MOID · 29.0 LD
- 0.0745 AU
- Tisserand (Jupiter)
- -0.598
Orbit quality
Orbit very well determined (uncertainty code 0).
- Observations used
- 8,518
- Data arc
- 158.4 years
- First observed
- 21 August 1835
- Last observed
- 11 January 1994
- Residual RMS
- 0.61 ″
- Solution · Davide Farnocchia
- 21 November 2025
Physical properties
- Mean radius
- 5.50 km
- Shape · km
- 14.9x8.2
Visual & observation
- Geometric albedo
- 0.04
- Absolute magnitude (H)
- 5.5
- Total magnitude M₁ · K₁ 8
- 5.5
Discovery & classification
Also known as 1P
Close approaches 5 on record
| When (UTC) | Body | Distance | Lunar distances | Relative speed |
|---|---|---|---|---|
| 2061-08-20 04:39:00 | Venus | 0.0544 AU | 21.2 LD | 78.9 km/s |
| 2134-04-09 13:28:00 | Venus | 0.1436 AU | 55.9 LD | 84.7 km/s |
| 2134-05-07 12:15:00 | Earth | 0.0916 AU | 35.6 LD | 65.3 km/s |
Next ten from today. 1 lunar distance = 384,400 km. Source: JPL close-approach data.
Sources
- orbital elements: JPL SBDB