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Centaur

2018 RG39

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(2018 RG39)

Where is it now

Distance from Sun
8.92 AU
True anomaly
182.88°
Distance from Earth
9.033 AU
As of
11 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.

Orbit of Mercury Orbit of Venus Orbit of Mars Sun Earth — 0.998 AU from the Sun Earth 2018 RG39 — 8.92 AU from the Sun 2018 RG39
Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. 2018 RG39 is 9.033 AU from Earth today (1.3 light-hours).

In the sky

Right ascension
18h 41m 37s
Declination
-37° 57′ 44″
Constellation
Corona Australis
Distance from Earth
9.04 AU
Elongation from the Sun
79.7° — well clear of the Sun

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
5.838 AU
Eccentricity
0.5303
Inclination
15.85°
Orbital period
14.1 years
Perihelion
2.742 AU
Aphelion
8.933 AU
Longitude of ascending node
33.83°
Argument of periapsis
68.94°
Epoch · J2000
2461200.5
Orbit class · CEN
Centaur
Earth MOID · 703.4 LD
1.8075 AU
Tisserand (Jupiter)
2.619

Orbit quality

Orbit very well determined (uncertainty code 1).

Observations used
96
Data arc
3.67 years
First observed
17 September 2017
Last observed
19 May 2021
Residual RMS
0.58 ″
Solution · Otto Matic
17 August 2026

Visual & observation

Absolute magnitude (H)
15.1

Discovery & classification

Centaur

Close approaches 7 on record

When (UTC) Body Distance Lunar distances Relative speed
2046-04-03 17:59:00 Juptr 0.9138 AU 355.6 LD 9.8 km/s
2077-04-27 14:57:00 Jupiter 0.3127 AU 121.7 LD 8.6 km/s
2077-04-27 14:57:00 Juptr 0.3127 AU 121.7 LD 8.6 km/s
2164-10-07 17:19:00 Juptr 1.4336 AU 557.9 LD 11.6 km/s

Next ten from today. 1 lunar distance = 384,400 km. Source: JPL close-approach data.

Sources