About 2I/Borisov
2I/Borisov is a mythic comet. It swings within 2.007 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 comet 176 EP
2I/Borisov
Position computed live · sbdb
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Live ephemeris
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Score breakdown
· 6 badgesMythic Top tier reached ✦
- Interstellar visitor +80
- 2I/Borisov, the first interstellar comet +60
- Hyperbolic comet (one pass, then gone) +18
- Has a proper name +8
- Comet +6
- Steeply tilted orbit (i > 40°) +4
Total score 176
Badges
- Comet · +6
- Interstellar visitor · +80
- Has a proper name · +8
- Hyperbolic comet (one pass, then gone) · +18
- Steeply tilted orbit (i > 40°) · +4
- 2I/Borisov, the first interstellar comet · +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.
What it actually is
- Its orbit family. On a hyperbolic orbit: it is moving too fast for the Sun's gravity to hold on to it.
- Closest approach. At its nearest it comes within 2.01 AU of the Sun — inside the orbit of Jupiter.
- One-way trip. On a hyperbolic path — it will leave the Solar System and never return.
- Steeply tilted. Its orbit is tipped 44° out of the flat plane the planets share — it spends most of its time well above or below them.
Standing on it
- Sunlight there. Even at its closest the sunlight is only about 25% as strong as Earth's.
- 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
- designation
- 2I
- eccentricity
- 3.3565
- full name
- C/2019 Q4 (Borisov)
- inclination
- 44.05
- interstellar
- yes
- mean motion deg day
- 1.254
- moid au
- 1.09
- name
- 2I/Borisov
- named
- yes
- orbit class
- HYP
- perihelion au
- 2.007
- semi major au
- -0.8515
How to see it
Like any astronomical target, 2I/Borisov 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 2I/Borisov is a mythic comet
2I/Borisov scores 176 points on Spacedle's rarity scale, which places it in the mythic tier.
That score comes from 6 science badges — Comet, Interstellar visitor, Has a proper name, Hyperbolic comet (one pass, then gone), Steeply tilted orbit (i > 40°) and 2I/Borisov, the first interstellar 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.