About 389P/Siding Spring
389P/Siding Spring is an uncommon comet. It swings within 1.66 AU of the Sun at perihelion.
A Jupiter-family comet, herded by Jupiter's gravity into a short orbit of under twenty years.
Uncommon comet 27 EP
389P/Siding Spring
Position computed live · sbdb
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Live ephemeris
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Score breakdown
· 4 badgesUncommon 34 pts → Rare
- Retrograde orbit +8
- Has a proper name +8
- Comet +6
- Jupiter-family comet +5
Total score 27
7 more points to reach Rare.
Badges
- Comet · +6
- Retrograde orbit · +8
- Has a proper name · +8
- Jupiter-family comet · +5
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 Jupiter-family comet, herded by Jupiter's gravity into a short orbit of under twenty years.
- Closest approach. At its nearest it comes within 1.66 AU of the Sun — inside the orbit of Jupiter.
- One lap. A single orbit around the Sun takes it about 13.3 years.
- How far it roams. Its orbit swings between 1.66 and 9.58 AU from the Sun.
Standing on it
- 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.
What's in a name
- Named. Notable enough to have earned a proper name, not just a catalogue number.
Properties
- aphelion au
- 9.58
- designation
- 389P
- eccentricity
- 0.7047
- full name
- 389P/Siding Spring
- inclination
- 160.07
- mean motion deg day
- 0.074
- moid au
- 0.765
- name
- 389P/Siding Spring
- named
- yes
- orbit class
- JFC
- perihelion au
- 1.66
- semi major au
- 5.62
How to see it
Like any astronomical target, 389P/Siding Spring 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 389P/Siding Spring is an uncommon comet
389P/Siding Spring scores 27 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 7 points would lift it into a rarer tier.
That score comes from 4 science badges — Comet, Retrograde orbit, Has a proper name and Jupiter-family 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.