Trans-Neptunian object

Mors-Somnus

341520 Mors-Somnus (2007 TY430)

Where is it now

Distance from Sun: 29.398 AU
True anomaly: 23.66°
Distance from Earth: 28.679 AU
As of: 16 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.

Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. Mors-Somnus is 28.679 AU from Earth today (4.0 light-hours).

In the sky

Right ascension: 04h 27m 34s
Declination: +12° 49′ 40″
Constellation: Taurus
Distance from Earth: 28.67 AU
Elongation from the Sun: 136.27° — 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.

Paste a location

How do I find my coordinates?

Google Maps on a computer

Right-click the spot where you'll be observing.
The first line of the menu is the coordinates, e.g. 51.50722, -0.12758 — click it and they're copied.
Paste them above.

Google Maps on a phone

Press and hold the spot to drop a pin.
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: 39.503 AU
Eccentricity: 0.2691
Inclination: 11.28°
Orbital period: 248.3 years
Perihelion: 28.874 AU
Aphelion: 50.133 AU
Longitude of ascending node: 196.7°
Argument of periapsis: 206.07°
Epoch · J2000: 2461200.5
Orbit class · TNO: Trans-Neptunian object
Earth MOID · 10,852.1 LD: 27.8851 AU
Tisserand (Jupiter): 5.337

Orbit quality

Orbit very well determined (uncertainty code 2).

Observations used: 365
Data arc: 18.31 years
First observed: 14 October 2007
Last observed: 4 February 2026
Residual RMS: 0.56 ″
Solution · Otto Matic: 7 June 2026

Physical properties

Rotation period: 9.28 hours

Visual & observation

Absolute magnitude (H): 6.79

Discovery & classification

Discovered by: Sheppard, S. S., Trujillo, C.
Discovery date: 14 October 2007
Discovery site: Mauna Kea

Mors and Somnus are twin gods of the underworld and offspring of Nox. Mors is the Roman personification of death and Somnus is the Roman personification of sleep. This object is an equal-sized binary in resonance with Neptune.

Also known as 341520 · 2007 TY430

Named TNO

Sources

visual properties: JPL SBDB (lookup)
physical properties: JPL SBDB (lookup)
orbital elements: JPL SBDB