About 1I/'Oumuamua
1I/'Oumuamua is a mythic asteroid. It swings within 0.256 AU of the Sun at perihelion.
A visitor from another star system — it doesn't belong to our Sun at all. Only a couple have ever been caught passing through.
Mythic asteroid 209 EP
1I/'Oumuamua
Position computed live · sbdb
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Live ephemeris
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Score breakdown
· 9 badgesMythic Top tier reached ✦
- Interstellar visitor +80
- 1I/ʻOumuamua, the first interstellar visitor +60
- Hyperbolic comet (one pass, then gone) +18
- Unbound (hyperbolic) orbit +16
- Wildly elliptical orbit +10
- Retrograde orbit +8
- Crosses Earth's orbit +8
- Has a proper name +8
- Asteroid +1
Total score 209
Badges
- Asteroid · +1
- Interstellar visitor · +80
- Retrograde orbit · +8
- Wildly elliptical orbit · +10
- Unbound (hyperbolic) orbit · +16
- Crosses Earth's orbit · +8
- Has a proper name · +8
- Hyperbolic comet (one pass, then gone) · +18
- 1I/ʻOumuamua, the first interstellar visitor · +60
Trivia
What makes it special
- Interstellar. A visitor from another star system — it doesn't belong to our Sun at all. Only a couple have ever been caught passing through.
- It crosses our path. Its orbit genuinely intersects Earth's track around the Sun. The two paths cross; only the timing keeps them apart.
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
- Closest approach. At its nearest it comes within 0.26 AU of the Sun — inside the orbit of Mercury.
- One-way trip. On a hyperbolic path — it will leave the Solar System and never return.
- Ancient. A leftover from the Solar System's birth, older than every continent on Earth.
Sense of scale
- Sense of scale. In everyday terms it is about 1.3 football pitches across.
Standing on it
- Sunlight there. At closest approach the Sun beats down about 15.3 times harder than it ever does on Earth.
Properties
- designation
- 1I
- eccentricity
- 1.2011
- full name
- 'Oumuamua (A/2017 U1)
- h mag
- 22.08
- inclination
- 122.74
- interstellar
- yes
- mean motion deg day
- 0.6867
- moid au
- 0.0958
- name
- 1I/'Oumuamua
- named
- yes
- orbit class
- HYA
- perihelion au
- 0.256
- rotation period h
- 7.937
- semi major au
- -1.272
How to see it
Like any astronomical target, 1I/'Oumuamua 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 1I/'Oumuamua is a mythic asteroid
1I/'Oumuamua scores 209 points on Spacedle's rarity scale, which places it in the mythic tier.
That score comes from 9 science badges — Asteroid, Interstellar visitor, Retrograde orbit, Wildly elliptical orbit, Unbound (hyperbolic) orbit, Crosses Earth's orbit, Has a proper name and Hyperbolic comet (one pass, then gone) — 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.