Swift-Tuttle
109P/Swift-Tuttle
Where is it now
- Distance from Sun
- 42.95 AU
- True anomaly
- 173.05°
- 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
- 09h 42m 25s
- Declination
- -18° 25′ 21″
- Constellation
- Hydra
- Distance from Earth
- 43.76 AU
- Elongation from the Sun
- 36.02° — near the Sun — look low at dusk or dawn
Favours the southern hemisphere; low or below the horizon from far north.
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
- 26.092 AU
- Eccentricity
- 0.9632
- Inclination
- 113.45°
- Orbital period
- 133.3 years
- Perihelion
- 0.96 AU
- Aphelion
- 51.225 AU
- Longitude of ascending node
- 139.38°
- Argument of periapsis
- 152.98°
- Epoch · J2000
- 2450000.5
- Orbit class · HTC
- Halley-type comet
- Earth MOID · 0.3 LD
- 0.0009 AU
- Tisserand (Jupiter)
- -0.28
Orbit quality
Orbit very well determined (uncertainty code 0).
- Observations used
- 652
- Data arc
- 257.7 years
- First observed
- 8 July 1737
- Last observed
- 29 March 1995
- Residual RMS
- 1.2 ″
- Solution · M.S.W. Keesey
- 9 October 2001
Physical properties
- Mean radius
- 13 km
Visual & observation
- Absolute magnitude (H)
- 4.5
- Total magnitude M₁ · K₁ 15
- 4.5
Discovery & classification
Also known as 109P
Close approaches 1 on record
| When (UTC) | Body | Distance | Lunar distances | Relative speed |
|---|---|---|---|---|
| 2126-08-05 15:50:00 | Earth | 0.1534 AU | 59.7 LD | 58.3 km/s |
Next ten from today. 1 lunar distance = 384,400 km. Source: JPL close-approach data.
Sources
- orbital elements: JPL SBDB