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Comet

Li

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C/1999 E1 (Li)

Li is a comet in the Halley-type comet orbit class. Its orbit takes it from 3.92 AU to 28.76 AU from the Sun; one orbit takes 66.06 years. Orbit from the JPL solution of 15 April 2021.

Where is it now

Distance from Sun
28.249 AU
True anomaly
173.87°
Distance from Earth
28.574 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 Li — 28.249 AU from the Sun Li
Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. Li is 28.574 AU from Earth today (4.0 light-hours).

In the sky

Right ascension
18h 32m 44s
Declination
+02° 08′ 39″
Constellation
Serpens
Distance from Earth
28.58 AU
Elongation from the Sun
69.63° — well clear of the Sun

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
16.341 AU
Eccentricity
0.7601
Inclination
46.88°
Orbital period
66.06 years
Perihelion
3.92 AU
Aphelion
28.761 AU
Longitude of ascending node
127.83°
Argument of periapsis
329.77°
Epoch · J2000
2451434.5
Orbit class · HTC
Halley-type comet
Earth MOID · 1,168.6 LD
3.0027 AU
Tisserand (Jupiter)
1.893

Orbit quality

Orbit reasonably well determined (uncertainty code 3).

Observations used
299
Data arc
843 days
First observed
6 December 1998
Last observed
28 March 2001
Residual RMS
0.68 ″
Solution · Otto Matic
15 April 2021

Visual & observation

Absolute magnitude (H)
10.6
Total magnitude M₁ · K₁ 4.5
10.6

Discovery & classification

Also known as 1999 E1

Named

Sources