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Comet

Lemmon

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C/2018 R5 (Lemmon)

Lemmon is a comet in the Halley-type comet orbit class. Its orbit takes it from 3.62 AU to 42.09 AU from the Sun; one orbit takes 109.3 years. Orbit from the JPL solution of 15 April 2021.

Where is it now

Distance from Sun
16.7 AU
True anomaly
135.54°
Distance from Earth
17.351 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 — 16.7 AU from the Sun Lemmon
Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. Lemmon is 17.351 AU from Earth today (2.4 light-hours).

In the sky

Right ascension
11h 03m 03s
Declination
-41° 09′ 59″
Constellation
Vela
Distance from Earth
17.35 AU
Elongation from the Sun
48.04° — near the Sun — look low at dusk or dawn

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
22.857 AU
Eccentricity
0.8416
Inclination
103.76°
Orbital period
109.3 years
Perihelion
3.621 AU
Aphelion
42.092 AU
Longitude of ascending node
171.14°
Argument of periapsis
178.01°
Epoch · J2000
2458380.5
Orbit class · HTC
Halley-type comet
Earth MOID · 1,017.9 LD
2.6157 AU
Tisserand (Jupiter)
-0.311

Orbit quality

Orbit reasonably well determined (uncertainty code 5).

Observations used
187
Data arc
131 days
First observed
5 July 2018
Last observed
13 November 2018
Residual RMS
0.48 ″
Solution · Otto Matic
15 April 2021

Visual & observation

Absolute magnitude (H)
14.4
Total magnitude M₁ · K₁ 4.5
14.4

Discovery & classification

Also known as 2018 R5

Named

Sources