About 161P/Hartley-IRAS
161P/Hartley-IRAS is a rare comet. It swings within 1.276 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.
Rare comet 38 EP
161P/Hartley-IRAS
Position computed live · sbdb
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Live ephemeris
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Score breakdown
· 4 badgesRare 50 pts → Epic
- Halley-type comet +16
- Retrograde orbit +8
- Has a proper name +8
- Comet +6
Total score 38
12 more points to reach Epic.
Badges
- Comet · +6
- Retrograde orbit · +8
- Has a proper name · +8
- Halley-type comet · +16
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 1.28 AU of the Sun — inside the orbit of Mars.
- One lap. A single orbit around the Sun takes it about 21.5 years.
- How far it roams. Its orbit swings between 1.28 and 14.17 AU from the Sun.
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.
- Tail. Its tail always points away from the Sun, never trailing behind its motion — it is blown, not dragged.
By the numbers
- Made of. A comet is a dirty snowball: water ice, frozen carbon dioxide and dust, held together loosely enough that some simply crumble when the Sun warms them.
Properties
- aphelion au
- 14.17
- designation
- 161P
- eccentricity
- 0.8348
- full name
- 161P/Hartley-IRAS
- inclination
- 95.69
- mean motion deg day
- 0.0459
- moid au
- 0.449
- name
- 161P/Hartley-IRAS
- named
- yes
- orbit class
- HTC
- perihelion au
- 1.276
- semi major au
- 7.723
How to see it
Like any astronomical target, 161P/Hartley-IRAS 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 161P/Hartley-IRAS is a rare comet
161P/Hartley-IRAS scores 38 points on Spacedle's rarity scale, which places it in the rare tier. Another 12 points would lift it into a rarer tier.
That score comes from 4 science badges — Comet, Retrograde orbit, Has a proper name and Halley-type comet — 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.