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Trans-Neptunian object

Lempo

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47171 Lempo (1999 TC36)

Where is it now

Distance from Sun
31.171 AU
True anomaly
25.77°
Distance from Earth
30.36 AU
As of
17 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 — 0.996 AU from the Sun Earth Lempo — 31.171 AU from the Sun Lempo
Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. Lempo is 30.36 AU from Earth today (4.2 light-hours).

In the sky

Right ascension
03h 56m 32s
Declination
+14° 57′ 00″
Constellation
Taurus
Distance from Earth
30.36 AU
Elongation from the Sun
143.96° — 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
39.656 AU
Eccentricity
0.2285
Inclination
8.4°
Orbital period
249.7 years
Perihelion
30.594 AU
Aphelion
48.719 AU
Longitude of ascending node
97.16°
Argument of periapsis
295.83°
Epoch · J2000
2461200.5
Orbit class · TNO
Trans-Neptunian object
Earth MOID · 11,522.6 LD
29.608 AU
Tisserand (Jupiter)
5.449

Orbit quality

Orbit very well determined (uncertainty code 1).

Observations used
1,143
Data arc
51.66 years
First observed
18 June 1974
Last observed
13 February 2026
Residual RMS
0.4 ″
Solution · Otto Matic
6 June 2026

Physical properties

Rotation period
6.21 hours

Visual & observation

Absolute magnitude (H)
4.94

Discovery & classification

Discovered by
Rubenstein, E. P., Strolger, L.-G.
Discovery date
1 October 1999
Discovery site
Kitt Peak

Lempo is the ancient Finnish devil who, with the help of his two demon cohorts, Hiisi and Paha, brought down the hero Väinämöinen. Within the trans-Neptunian triple system, the satellite (47171) Lempo I was discovered on 2001 Dec. 8 by C. A. Trujillo and M. E. Brown using the Hubble Space Telescope (HST), and is named Paha. The primary was identified as a binary by S. D. Benecchi et al. through re-analysis of the HST data originally obtained by Trujillo and Brown. Lempo refers to the larger component of the central binary and Hiisi to the smaller component.

Also known as 47171 · 1999 TC36

Named TNO

Sources