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Trans-Neptunian object

Deucalion

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53311 Deucalion (1999 HU11)

Where is it now

Distance from Sun
42.334 AU
True anomaly
305.49°
Distance from Earth
43.179 AU
As of
20 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 Deucalion — 42.334 AU from the Sun Deucalion
Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. Deucalion is 43.179 AU from Earth today (6.0 light-hours).

In the sky

Right ascension
15h 46m 40s
Declination
-19° 57′ 54″
Constellation
Libra
Distance from Earth
43.19 AU
Elongation from the Sun
30.77° — 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
43.941 AU
Eccentricity
0.0591
Inclination
0.37°
Orbital period
291.3 years
Perihelion
41.342 AU
Aphelion
46.54 AU
Longitude of ascending node
51.29°
Argument of periapsis
242.81°
Epoch · J2000
2461200.5
Orbit class · TNO
Trans-Neptunian object
Earth MOID · 15,693.5 LD
40.3254 AU
Tisserand (Jupiter)
5.92

Orbit quality

Orbit very well determined (uncertainty code 2).

Observations used
128
Data arc
21.2 years
First observed
12 April 1999
Last observed
24 June 2020
Residual RMS
0.78 ″
Solution · Otto Matic
13 April 2021

Visual & observation

Absolute magnitude (H)
6.71

Discovery & classification

Discovered by
Deep Ecliptic Survey
Discovery date
18 April 1999
Discovery site
Kitt Peak

After a flood in which all humans were drowned except for Deucalion and Pyrrha, an oracle tells them to “throw the bones of their mother” behind them. Puzzled, they decided that their mother is Earth and her bones are stones. The stones they then threw over their shoulders sprang up into people to repopulate the world.

Also known as 53311 · 1999 HU11

Named TNO

Sources