About C/2021 S4 (Tsuchinshan)
C/2021 S4 (Tsuchinshan) is an epic comet. It swings within 6.689 AU of the Sun at perihelion.
A Chiron-type comet, orbiting out among the giant planets rather than diving into the inner Solar System.
Epic comet 60 EP
C/2021 S4 (Tsuchinshan)
Position computed live · sbdb
Loading sky survey…
Live ephemeris
This object moves — fetching its current position…
Score breakdown
· 5 badgesEpic 78 pts → Anomaly
- Chiron-type comet +22
- Far-flung orbit (a > 50 AU) +14
- Never comes near the Sun +10
- Has a proper name +8
- Comet +6
Total score 60
18 more points to reach Anomaly.
Badges
- Comet · +6
- Has a proper name · +8
- Chiron-type comet · +22
- Far-flung orbit (a > 50 AU) · +14
- Never comes near the Sun · +10
Trivia
What it actually is
- Its orbit family. A Chiron-type comet, orbiting out among the giant planets rather than diving into the inner Solar System.
- Closest approach. At its nearest it comes within 6.69 AU of the Sun — inside the orbit of Saturn.
- One lap. A single orbit around the Sun takes it about 2110 years.
- How far it roams. Its orbit swings between 6.7 and 322.3 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
- 322.3
- designation
- 2021 S4
- eccentricity
- 0.9593
- full name
- C/2021 S4 (Tsuchinshan)
- inclination
- 17.48
- mean motion deg day
- 0.0005
- moid au
- 5.75
- name
- C/2021 S4 (Tsuchinshan)
- named
- yes
- orbit class
- CTc
- perihelion au
- 6.689
- semi major au
- 164.5
How to see it
Like any astronomical target, C/2021 S4 (Tsuchinshan) 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 C/2021 S4 (Tsuchinshan) is an epic comet
C/2021 S4 (Tsuchinshan) scores 60 points on Spacedle's rarity scale, which places it in the epic tier. Another 18 points would lift it into a rarer tier.
That score comes from 5 science badges — Comet, Has a proper name, Chiron-type comet, Far-flung orbit (a > 50 AU) and Never comes near the Sun — 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.