About 109P/Swift-Tuttle
109P/Swift-Tuttle is an epic comet. It swings within 0.96 AU of the Sun at perihelion.
A Halley-type comet: 20 to 200 years per lap, on a steeply tilted orbit that reaches far beyond the planets.
Epic comet 56 EP
109P/Swift-Tuttle
Position computed live · sbdb
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Live ephemeris
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Score breakdown
· 5 badgesEpic 78 pts → Anomaly
- Passes within two lunar distances of Earth's orbit +18
- Halley-type comet +16
- Retrograde orbit +8
- Has a proper name +8
- Comet +6
Total score 56
22 more points to reach Anomaly.
Badges
- Comet · +6
- Retrograde orbit · +8
- Has a proper name · +8
- Halley-type comet · +16
- Passes within two lunar distances of Earth's orbit · +18
Trivia
Hard to believe
- Against the traffic. It goes round the Sun backwards, against the direction every planet and almost everything else travels.
What it actually is
- Its orbit family. A Halley-type comet: 20 to 200 years per lap, on a steeply tilted orbit that reaches far beyond the planets.
- Closest approach. At its nearest it comes within 0.96 AU of the Sun — inside the orbit of Earth.
- One lap. A single orbit around the Sun takes it about 133 years.
- How far it roams. Its orbit swings between 0.96 and 51.22 AU from the Sun.
Sense of scale
- Sense of scale. In everyday terms it is roughly 2.9× the height of Mount Everest.
- Walk around it. Walking its equator at a steady pace, eight hours a day, would take about 2 days.
Standing on it
- Growing a tail. Once inside roughly the orbit of Mars the ice starts turning straight to gas, blowing out the coma and tail that make a comet a comet.
Properties
- aphelion au
- 51.22
- designation
- 109P
- diameter km
- 26
- eccentricity
- 0.9632
- full name
- 109P/Swift-Tuttle
- inclination
- 113.45
- mean motion deg day
- 0.0074
- moid au
- 0.0009
- name
- 109P/Swift-Tuttle
- named
- yes
- orbit class
- HTC
- perihelion au
- 0.96
- semi major au
- 26.09
How to see it
Like any astronomical target, 109P/Swift-Tuttle is best seen from a dark site away from city lights, and when it is above the horizon depends on your latitude and the time of year. Because it moves against the background stars, the live position panel on this page tracks where it is right now. The visibility panel above works out tonight's viewing window for your saved location.
Why 109P/Swift-Tuttle is an epic comet
109P/Swift-Tuttle scores 56 points on Spacedle's rarity scale, which places it in the epic tier. Another 22 points would lift it into a rarer tier.
That score comes from 5 science badges — Comet, Retrograde orbit, Has a proper name, Halley-type comet and Passes within two lunar distances of Earth's orbit — each earned for a real, measurable property of the object. Rarity on Spacedle is never random: the more remarkable an object's astrophysics, the more badges it collects, the higher it scores, and the rarer it ranks.