About 17P/Holmes
17P/Holmes is a common comet. It swings within 2.066 AU of the Sun at perihelion.
A Jupiter-family comet, herded by Jupiter's gravity into a short orbit of under twenty years.
Common comet 19 EP
17P/Holmes
Position computed live · sbdb
Loading sky survey…
Live ephemeris
This object moves — fetching its current position…
Score breakdown
· 3 badgesCommon 22 pts → Uncommon
- Has a proper name +8
- Comet +6
- Jupiter-family comet +5
Total score 19
3 more points to reach Uncommon.
Badges
- Comet · +6
- Has a proper name · +8
- Jupiter-family comet · +5
Trivia
What it actually is
- Its orbit family. A Jupiter-family comet, herded by Jupiter's gravity into a short orbit of under twenty years.
- Closest approach. At its nearest it comes within 2.07 AU of the Sun — inside the orbit of Jupiter.
- One lap. A single orbit around the Sun takes it about 6.9 years.
- How far it roams. Its orbit swings between 2.07 and 5.19 AU from the Sun.
Sense of scale
- Sense of scale. In everyday terms it is roughly 0.4× the height of Mount Everest.
Standing on it
- Sunlight there. Even at its closest the sunlight is only about 23% 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
- Size. Roughly 3.4 km across.
Properties
- aphelion au
- 5.19
- designation
- 17P
- diameter km
- 3.42
- eccentricity
- 0.4302
- full name
- 17P/Holmes
- inclination
- 19.07
- mean motion deg day
- 0.1427
- moid au
- 1.07
- name
- 17P/Holmes
- named
- yes
- orbit class
- JFc
- perihelion au
- 2.066
- semi major au
- 3.626
How to see it
Like any astronomical target, 17P/Holmes 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 17P/Holmes is a common comet
17P/Holmes scores 19 points on Spacedle's rarity scale, which places it in the common tier. Another 3 points would lift it into a rarer tier.
That score comes from 3 science badges — Comet, Has a proper name and Jupiter-family 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.