← Back to dex - Centaur: adrift between the giants +20
- Kuiper-belt object +5
- Catalogue designation only +0
Total score 25
9 more points to reach Rare.
Badges
- ❄️ Kuiper-belt object · +5
- 🔢 Catalogue designation only
- 🦌 Centaur: adrift between the giants · +20
✨ Trivia
What it actually is
- 🛸 Its orbit family. A centaur, wandering between the orbits of Jupiter and Neptune on a path nothing can stabilise. Half asteroid and half comet, and gone from this orbit within a few million years.
- 🌞 Closest approach. At its nearest it comes within 3.8 AU of the Sun — inside the orbit of Jupiter.
- 🔁 One lap. A single orbit around the Sun takes it about 24.8 years.
- 🥏 How far it roams. Its orbit swings between 3.8 and 13.2 AU from the Sun.
Sense of scale
- 🧱 Sense of scale. In everyday terms it is roughly 1.4× the height of Mount Everest.
- 🚶 Walk around it. Walking its equator at a steady pace, eight hours a day, would take about 23.3 hours.
By the numbers
- 📐 Estimated size. Nobody has measured its size directly. Assuming it reflects light like a typical asteroid, its brightness implies something roughly 12.4 km across.
What's in a name
- 🔢 Designation. Known only by its catalogue designation — no name yet.
Properties
- aphelion au
- 13.2
- designation
- 717021
- eccentricity
- 0.553
- full name
- 717021 (2016 ND21)
- h mag
- 12.29
- inclination
- 21.76
- mean motion deg day
- 0.0398
- moid au
- 2.86
- name
- (717021) 2016 ND21
- number only
- yes
- orbit class
- CEN
- perihelion au
- 3.799
- rotation period h
- 17.53
- semi major au
- 8.499
About (717021) 2016 ND21
(717021) 2016 ND21 is an uncommon kbo. It swings within 3.799 AU of the Sun at perihelion.
A centaur, wandering between the orbits of Jupiter and Neptune on a path nothing can stabilise. Half asteroid and half comet, and gone from this orbit within a few million years.
How to see it
Like any astronomical target, (717021) 2016 ND21 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 (717021) 2016 ND21 is an uncommon kbo
(717021) 2016 ND21 scores 25 points on Spacedle's rarity scale, which places it in the uncommon tier. Another 9 points would lift it into a rarer tier.
That score comes from 3 science badges — Kuiper-belt object, Catalogue designation only and Centaur: adrift between the giants — 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.