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Comet Near-Earth

Crommelin

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27P/Crommelin

Where is it now

Distance from Sun
17.322 AU
True anomaly
182.09°
Distance from Earth
17.71 AU
As of
11 October 2026

Two-body Kepler propagation — accurate to ~0.1% for major planets over decades, less so for highly-perturbed bodies. Use JPL Horizons for high precision.

Sun Earth — 0.998 AU from the Sun Earth Crommelin — 17.322 AU from the Sun Crommelin
Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. Crommelin is 17.71 AU from Earth today (2.5 light-hours).

In the sky

Right ascension
17h 34m 40s
Declination
-14° 48′ 10″
Constellation
Serpens
Distance from Earth
17.72 AU
Elongation from the Sun
65.02° — well clear of the Sun

Visible from both hemispheres.

From your location

See how high it is right now, whether it is up after civil twilight, and when it rises and sets where you are.

How do I find my coordinates?

Google Maps on a computer

  1. Right-click the spot where you'll be observing.
  2. The first line of the menu is the coordinates, e.g. 51.50722, -0.12758 — click it and they're copied.
  3. Paste them above.

Google Maps on a phone

  1. Press and hold the spot to drop a pin.
  2. The coordinates appear in the search bar (or on the pin's card) — tap to copy, then paste above.

A full Google Maps link works too, but the short maps.app.goo.gl share links don't carry coordinates — copy the numbers instead. We round to about a kilometre; that's all the sky calculation needs.

Know your what3words address? Paste it, e.g. ///filled.count.soap. This is optional — the three words are sent to what3words to convert them, and we don't store the address or the result.

Your location stays in your browser and is sent only for this calculation. Using a what3words address is optional; if you do, the three words go to what3words to be converted and we don't record them. Set a location first, then you can save an email alert for this object. See our privacy policy.

Two-body approximation, good to about a degree for the planets — enough to find the constellation and know whether it is up.

Orbital elements

Semi-major axis
9.093 AU
Eccentricity
0.9193
Inclination
29.22°
Orbital period
27.42 years
Perihelion
0.734 AU
Aphelion
17.453 AU
Longitude of ascending node
250.96°
Argument of periapsis
195.96°
Epoch · J2000
2452489.5
Orbit class · HTC
Halley-type comet
Earth MOID · 89.0 LD
0.2287 AU
Tisserand (Jupiter)
1.481

Orbit quality

Orbit very well determined (uncertainty code 0).

Observations used
455
Data arc
55.31 years
First observed
3 October 1956
Last observed
26 January 2012
Residual RMS
0.83 ″
Solution · Davide Farnocchia
12 May 2023

Visual & observation

Absolute magnitude (H)
12.7
Total magnitude M₁ · K₁ 27.8
12.7

Discovery & classification

Discovered by
Pons, Jean Louis
Discovery date
23 February 1818
Discovery site
Marseilles Observatory, France

Also known as 27P · 1818 I · 1873 VII · 1873g · 1928 III · 1928b · 1956 VI · 1956g

Near-Earth Object Named

Close approaches 5 on record

Flyby geometry
Ecliptic flyby of Crommelin at 2120-12-22 22:15 UTC Top-down view of the ecliptic, Earth at the centre, for the 2120-12-22 22:15 UTC close approach of Crommelin. Catalogue miss distance 115.7 LD · 4.45 × 10⁷ km. The curve is the geocentric path from 2120-12-19 to 2120-12-25, with a mark at UTC midnights and an arrow for the direction of motion. The circle is the Moon’s mean orbit; the Moon is plotted at closest approach. A ray shows the Sun’s direction. The labelled distance is the full separation. The drawn radius is the part that lies in the ecliptic plane. At closest approach the object is north of the ecliptic. The path is approximate: a two-body Kepler propagation of the catalogue orbital elements, not a numerical integration. The Moon’s position is approximate. The inset is a heliocentric view and is approximate. approximate Sun 115.7 LD · 4.45 × 10⁷ km 2120-12-22 22:15 UTC Earth Moon Heliocentric, approximate

Top-down view of the ecliptic, Earth at the centre, for the 2120-12-22 22:15 UTC close approach of Crommelin. Catalogue miss distance 115.7 LD · 4.45 × 10⁷ km. The curve is the geocentric path from 2120-12-19 to 2120-12-25, with a mark at UTC midnights and an arrow for the direction of motion. The circle is the Moon’s mean orbit; the Moon is plotted at closest approach. A ray shows the Sun’s direction. The labelled distance is the full separation. The drawn radius is the part that lies in the ecliptic plane. At closest approach the object is north of the ecliptic. The path is approximate: a two-body Kepler propagation of the catalogue orbital elements, not a numerical integration. The Moon’s position is approximate. The inset is a heliocentric view and is approximate.

When (UTC) Body Distance Lunar distances Relative speed
2120-12-22 22:15:00 Earth 0.2972 AU 115.7 LD 26.1 km/s
2149-05-02 21:50:00 Juptr 1.4956 AU 582.0 LD 18.7 km/s

Next ten from today. 1 lunar distance = 384,400 km. Source: JPL close-approach data.

Sources