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Comet

Helin

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151P/Helin

Where is it now

Distance from Sun
6.787 AU
True anomaly
222.16°
Distance from Earth
7.76 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 — 6.787 AU from the Sun Helin
Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. Helin is 7.76 AU from Earth today (1.1 light-hours).

In the sky

Right ascension
14h 34m 54s
Declination
-10° 55′ 14″
Constellation
Libra
Distance from Earth
7.76 AU
Elongation from the Sun
10.43° — too close to the Sun to observe

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
5.807 AU
Eccentricity
0.5709
Inclination
4.73°
Orbital period
13.99 years
Perihelion
2.492 AU
Aphelion
9.123 AU
Longitude of ascending node
143.55°
Argument of periapsis
215.53°
Epoch · J2000
2455249.5
Orbit class · JFc
Jupiter-family comet (P < 20 y)
Earth MOID · 579.7 LD
1.4897 AU
Tisserand (Jupiter)
2.625

Orbit quality

Orbit very well determined (uncertainty code 1).

Observations used
420
Data arc
28.42 years
First observed
24 August 1987
Last observed
26 January 2016
Residual RMS
0.55 ″
Solution · Otto Matic
19 May 2022

Physical properties

Mean radius
4.20 km

Visual & observation

Absolute magnitude (H)
8.5
Total magnitude M₁ · K₁ 21.8
8.5

Discovery & classification

Also known as 151P · 151P/1987 Q3 · 151P/2001 M1 · 1987 XVII · 1987w

Named

Close approaches 11 on record

When (UTC) Body Distance Lunar distances Relative speed
2073-06-29 06:40:00 Juptr 0.8003 AU 311.5 LD 5.6 km/s
2148-10-06 05:27:00 Juptr 1.0055 AU 391.3 LD 9.7 km/s
2156-12-03 02:36:00 Satrn 0.7933 AU 308.7 LD 3.2 km/s
2160-08-21 21:34:00 Juptr 1.8223 AU 709.2 LD 4.7 km/s
2162-06-04 15:06:00 Juptr 1.9469 AU 757.7 LD 4.8 km/s
2192-05-23 07:39:00 Juptr 1.5015 AU 584.3 LD 4.8 km/s

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

Sources