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Trans-Neptunian object

1999 SA28

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(1999 SA28)

Where is it now

Distance from Sun
34.327 AU
True anomaly
55.86°
Distance from Earth
33.356 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.

Sun Earth — 0.997 AU from the Sun Earth 1999 SA28 — 34.327 AU from the Sun 1999 SA28
Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. 1999 SA28 is 33.356 AU from Earth today (4.6 light-hours).

In the sky

Right ascension
01h 51m 34s
Declination
+20° 50′ 07″
Constellation
Aries
Distance from Earth
33.36 AU
Elongation from the Sun
167° — near opposition — up most of the night

Favours the northern hemisphere; low or below the horizon from far south.

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
39.228 AU
Eccentricity
0.1848
Inclination
11.11°
Orbital period
245.7 years
Perihelion
31.977 AU
Aphelion
46.479 AU
Longitude of ascending node
262.7°
Argument of periapsis
73.92°
Epoch · J2000
2451438.5
Orbit class · TNO
Trans-Neptunian object
Earth MOID · 12,058.7 LD
30.9854 AU
Tisserand (Jupiter)
5.428

Orbit quality

Orbit very uncertain — the object may be effectively lost (uncertainty code 9).

Observations used
6
Data arc
24 hours
First observed
16 September 1999
Last observed
17 September 1999
Residual RMS
0.08 ″
Solution · Otto Matic
14 April 2021

Visual & observation

Absolute magnitude (H)
7.25

Discovery & classification

TNO

Sources