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Comet Near-Earth

Lemmon

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405P/Lemmon

Where is it now

Distance from Sun
3.751 AU
True anomaly
224.07°
Distance from Earth
3.196 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 — 3.751 AU from the Sun Lemmon
Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. Lemmon is 3.196 AU from Earth today (26.6 light-minutes).

In the sky

Right ascension
22h 00m 04s
Declination
-16° 53′ 21″
Constellation
Aquarius
Distance from Earth
3.2 AU
Elongation from the Sun
116.43° — 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
3.607 AU
Eccentricity
0.6891
Inclination
9.37°
Orbital period
6.85 years
Perihelion
1.121 AU
Aphelion
6.093 AU
Longitude of ascending node
3.31°
Argument of periapsis
112.29°
Epoch · J2000
2458091.5
Orbit class · JFc
Jupiter-family comet (P < 20 y)
Earth MOID · 79.6 LD
0.2044 AU
Tisserand (Jupiter)
2.633

Orbit quality

Orbit very well determined (uncertainty code 0).

Observations used
1,017
Data arc
7.6 years
First observed
4 October 2013
Last observed
10 May 2021
Residual RMS
0.69 ″
Solution · Otto Matic
31 May 2021

Visual & observation

Absolute magnitude (H)
18.8
Total magnitude M₁ · K₁ 4.5
18.8

Discovery & classification

Also known as 405P · 405P/2013 TL117 · 405P/2020 U1

Near-Earth Object Named

Close approaches 21 on record

Flyby geometry
Ecliptic flyby of Lemmon at 2068-02-21 10:20 UTC Top-down view of the ecliptic, Earth at the centre, for the 2068-02-21 10:20 UTC close approach of Lemmon. Catalogue miss distance 125.7 LD · 4.83 × 10⁷ km. The curve is the geocentric path from 2068-02-18 to 2068-02-24, with a mark at UTC midnights and an arrow for the direction of motion. The circle is the Moon’s mean orbit; the Moon is plotted at closest approach. A ray shows the Sun’s direction. The labelled distance is the full separation. The drawn radius is the part that lies in the ecliptic plane. At closest approach the object is north of the ecliptic. The path is a geocentric ecliptic ephemeris from JPL Horizons. The inset is a heliocentric view and is approximate. Sun 125.7 LD · 4.83 × 10⁷ km 2068-02-21 10:20 UTC Earth Moon Heliocentric, approximate

Top-down view of the ecliptic, Earth at the centre, for the 2068-02-21 10:20 UTC close approach of Lemmon. Catalogue miss distance 125.7 LD · 4.83 × 10⁷ km. The curve is the geocentric path from 2068-02-18 to 2068-02-24, with a mark at UTC midnights and an arrow for the direction of motion. The circle is the Moon’s mean orbit; the Moon is plotted at closest approach. A ray shows the Sun’s direction. The labelled distance is the full separation. The drawn radius is the part that lies in the ecliptic plane. At closest approach the object is north of the ecliptic. The path is a geocentric ecliptic ephemeris from JPL Horizons. The inset is a heliocentric view and is approximate.

JPL Horizons

When (UTC) Body Distance Lunar distances Relative speed
2033-03-21 00:25:00 Juptr 1.0632 AU 413.8 LD 10.9 km/s
2044-01-26 16:28:00 Juptr 1.1329 AU 440.9 LD 6.8 km/s
2068-02-21 10:20:00 Earth 0.3229 AU 125.7 LD 15.4 km/s
2092-03-25 06:42:00 Juptr 1.0219 AU 397.7 LD 6.8 km/s
2103-02-04 14:25:00 Juptr 1.5315 AU 596.0 LD 11.6 km/s
2122-01-06 10:37:00 Earth 0.3064 AU 119.3 LD 9.7 km/s
2139-08-21 22:04:00 Juptr 1.06 AU 412.5 LD 6.7 km/s
2150-08-10 09:55:00 Juptr 1.957 AU 761.6 LD 13 km/s
2156-02-01 16:41:00 Earth 0.2136 AU 83.1 LD 8.9 km/s
2175-05-18 05:34:00 Juptr 1.5289 AU 595.0 LD 12.4 km/s

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

Sources