About (528381) 2008 ST291
(528381) 2008 ST291 is a rare kbo. It swings within 42.602 AU of the Sun at perihelion.
A trans-Neptunian object from the Kuiper Belt, out where the Sun is little more than the brightest star in a very dark sky.
Rare kbo 39 EP
(528381) 2008 ST291
Position computed live · sbdb
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Live ephemeris
This object moves — fetching its current position…
Score breakdown
· 5 badgesRare 50 pts → Epic
- Far-flung orbit (a > 50 AU) +14
- Trans-Neptunian object +12
- Notably bright (low H) +8
- Kuiper-belt object +5
- Catalogue designation only +0
Total score 39
11 more points to reach Epic.
Badges
- Kuiper-belt object · +5
- Notably bright (low H) · +8
- Catalogue designation only
- Trans-Neptunian object · +12
- Far-flung orbit (a > 50 AU) · +14
Trivia
What it actually is
- Its orbit family. A trans-Neptunian object from the Kuiper Belt, out where the Sun is little more than the brightest star in a very dark sky.
- One lap. A single orbit around the Sun takes it about 991 years.
- How far it roams. Its orbit swings between 42.6 and 156.22 AU from the Sun.
Sense of scale
- Sense of scale. In everyday terms it is about 23.6× the length of Manhattan island.
- Walk around it. Walking its equator at a steady pace, eight hours a day, would take about 40 days.
By the numbers
- Estimated size. Nobody has measured its size directly. Assuming it reflects light like a typical asteroid, its brightness implies something roughly 509 km across.
What's in a name
- Designation. Known only by its catalogue designation — no name yet.
Properties
- aphelion au
- 156.22
- designation
- 528381
- eccentricity
- 0.5715
- full name
- 528381 (2008 ST291)
- h mag
- 4.22
- inclination
- 20.81
- mean motion deg day
- 0.001
- moid au
- 41.6
- name
- (528381) 2008 ST291
- number only
- yes
- orbit class
- TNO
- perihelion au
- 42.602
- semi major au
- 99.41
How to see it
Like any astronomical target, (528381) 2008 ST291 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 (528381) 2008 ST291 is a rare kbo
(528381) 2008 ST291 scores 39 points on Spacedle's rarity scale, which places it in the rare tier. Another 11 points would lift it into a rarer tier.
That score comes from 5 science badges — Kuiper-belt object, Notably bright (low H), Catalogue designation only, Trans-Neptunian object and Far-flung orbit (a > 50 AU) — 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.