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Comet

Lemmon

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C/2018 DO4 (Lemmon)

Lemmon is a comet in the Halley-type comet orbit class. Its orbit takes it from 2.41 AU to 49.31 AU from the Sun; one orbit takes 131.5 years. Orbit from the JPL solution of 28 June 2022.

Where is it now

Distance from Sun
16.984 AU
True anomaly
143.59°
Distance from Earth
17.204 AU
As of
24 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 — 0.994 AU from the Sun Earth Lemmon — 16.984 AU from the Sun Lemmon
Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. Lemmon is 17.204 AU from Earth today (2.4 light-hours).

In the sky

Right ascension
19h 19m 16s
Declination
-34° 39′ 26″
Constellation
Sagittarius
Distance from Earth
17.21 AU
Elongation from the Sun
75.16° — 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
25.858 AU
Eccentricity
0.907
Inclination
160.47°
Orbital period
131.5 years
Perihelion
2.406 AU
Aphelion
49.309 AU
Longitude of ascending node
251.13°
Argument of periapsis
175.97°
Epoch · J2000
2458673.5
Orbit class · HTC
Halley-type comet
Earth MOID · 553.0 LD
1.421 AU
Tisserand (Jupiter)
-1.569

Orbit quality

Orbit very well determined (uncertainty code 1).

Observations used
660
Data arc
6.21 years
First observed
5 April 2016
Last observed
22 June 2022
Residual RMS
0.42 ″
Solution · Otto Matic
28 June 2022

Visual & observation

Absolute magnitude (H)
13.2
Total magnitude M₁ · K₁ 6.5
13.2

Discovery & classification

Also known as 2018 DO4

Named

Close approaches 1 on record

When (UTC) Body Distance Lunar distances Relative speed
2146-08-01 08:11:00 Juptr 1.7482 AU 680.3 LD 29.1 km/s

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

Sources