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Comet

Lemmon

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397P/Lemmon

Where is it now

Distance from Sun
3.639 AU
True anomaly
254.13°
Distance from Earth
4.136 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 Lemmon — 3.639 AU from the Sun Lemmon
Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. Lemmon is 4.136 AU from Earth today (34.4 light-minutes).

In the sky

Right ascension
17h 25m 52s
Declination
-32° 52′ 48″
Constellation
Scorpius
Distance from Earth
4.14 AU
Elongation from the Sun
53.55° — 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
3.86 AU
Eccentricity
0.4006
Inclination
11.02°
Orbital period
7.58 years
Perihelion
2.314 AU
Aphelion
5.406 AU
Longitude of ascending node
8.97°
Argument of periapsis
12.49°
Epoch · J2000
2458013.5
Orbit class · JFc
Jupiter-family comet (P < 20 y)
Earth MOID · 512.5 LD
1.3169 AU
Tisserand (Jupiter)
2.897

Orbit quality

Orbit very well determined (uncertainty code 1).

Observations used
484
Data arc
16.21 years
First observed
2 December 2004
Last observed
17 February 2021
Residual RMS
0.67 ″
Solution · Otto Matic
9 April 2025

Visual & observation

Absolute magnitude (H)
15.5
Total magnitude M₁ · K₁ 4.5
15.5

Discovery & classification

Also known as 397P · 397P/2012 SB6 · 397P/2020 M2

Named

Close approaches 19 on record

When (UTC) Body Distance Lunar distances Relative speed
2076-02-18 23:14:00 Juptr 0.1831 AU 71.3 LD 4.7 km/s
2076-02-18 23:14:00 Jupiter 0.1831 AU 71.3 LD 4.7 km/s
2082-11-12 19:57:00 Juptr 1.6286 AU 633.8 LD 4.9 km/s
2090-11-06 07:20:00 Juptr 1.7063 AU 664.0 LD 7.4 km/s
2135-09-19 16:20:00 Juptr 1.8007 AU 700.8 LD 7.7 km/s
2143-09-27 18:35:00 Juptr 1.6716 AU 650.6 LD 4.6 km/s
2150-06-14 16:07:00 Jupiter 0.3761 AU 146.4 LD 4 km/s
2150-06-14 16:07:00 Juptr 0.3761 AU 146.4 LD 4 km/s
2181-05-14 04:48:00 Juptr 1.5293 AU 595.2 LD 3.3 km/s
2185-10-28 10:03:00 Jupiter 0.3947 AU 153.6 LD 4 km/s

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

Sources