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Comet

Helin-Roman-Crockett

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111P/Helin-Roman-Crockett

Where is it now

Distance from Sun
4.518 AU
True anomaly
214.54°
Distance from Earth
4.484 AU
As of
22 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.

Orbit of Mercury Orbit of Venus Orbit of Mars Sun Earth — 0.995 AU from the Sun Earth Helin-Roman-Crockett — 4.518 AU from the Sun Helin-Roman-Crockett
Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. Helin-Roman-Crockett is 4.484 AU from Earth today (37.3 light-minutes).

In the sky

Right ascension
19h 49m 50s
Declination
-23° 42′ 10″
Constellation
Sagittarius
Distance from Earth
4.49 AU
Elongation from the Sun
85.13° — well clear of the Sun

Favours the southern hemisphere; low or below the horizon from far north.

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
4.16 AU
Eccentricity
0.1096
Inclination
4.23°
Orbital period
8.49 years
Perihelion
3.704 AU
Aphelion
4.616 AU
Longitude of ascending node
89.79°
Argument of periapsis
3.38°
Epoch · J2000
2456320.5
Orbit class · ETc
Encke-type comet
Earth MOID · 1,058.9 LD
2.721 AU
Tisserand (Jupiter)
3.023

Orbit quality

Orbit very well determined (uncertainty code 1).

Observations used
137
Data arc
23.96 years
First observed
3 January 1989
Last observed
21 December 2012
Residual RMS
0.79 ″
Solution · Alan B. Chamberlin
28 January 2013

Physical properties

Mean radius
0.60 km

Visual & observation

Absolute magnitude (H)
8.4
Total magnitude M₁ · K₁ 17
8.4

Discovery & classification

Discovered by
Helin, Eleanor
Discovery date
2 January 1989
Discovery site
Palomar Mountain Observatory

Also known as 111P · 111P/1989 A2 · 1988 XIII · 1989b

Named

Close approaches 25 on record

When (UTC) Body Distance Lunar distances Relative speed
2040-01-26 12:19:00 Juptr 1.4093 AU 548.5 LD 2.4 km/s
2071-04-29 17:28:00 Juptr 0.0361 AU 14.1 LD 6.5 km/s
2071-04-29 17:28:00 Jupiter 0.0361 AU 14.1 LD 6.5 km/s
2073-03-10 15:59:00 Juptr 0.0388 AU 15.1 LD 6.2 km/s
2073-03-10 15:59:00 Jupiter 0.0388 AU 15.1 LD 6.2 km/s
2075-12-05 12:45:00 Juptr 0.0681 AU 26.5 LD 4.4 km/s
2075-12-05 12:45:00 Jupiter 0.0681 AU 26.5 LD 4.4 km/s
2078-04-04 06:13:00 Juptr 0.076 AU 29.6 LD 4.2 km/s
2078-04-04 06:13:00 Jupiter 0.076 AU 29.6 LD 4.2 km/s
2080-05-01 03:58:00 Juptr 0.0583 AU 22.7 LD 4.9 km/s

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

Sources