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Asteroid Near-Earth

Orthos

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2329 Orthos (1976 WA)

Where is it now

Distance from Sun
3.939 AU
True anomaly
173.42°
Distance from Earth
4.413 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 Orthos — 3.939 AU from the Sun Orthos
Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. Orthos is 4.413 AU from Earth today (36.7 light-minutes).

In the sky

Right ascension
09h 26m 53s
Declination
+00° 25′ 16″
Constellation
Hydra
Distance from Earth
4.41 AU
Elongation from the Sun
56.29° — near the Sun — look low at dusk or dawn

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
2.412 AU
Eccentricity
0.6532
Inclination
24.5°
Orbital period
3.75 years
Perihelion
0.837 AU
Aphelion
3.988 AU
Longitude of ascending node
169.12°
Argument of periapsis
146.26°
Epoch · J2000
2461200.5
Orbit class · APO
Apollo
Earth MOID · 36.5 LD
0.0937 AU
Tisserand (Jupiter)
3.095

Orbit quality

Orbit very well determined (uncertainty code 0).

Observations used
1,999
Data arc
49.76 years
First observed
31 May 1976
Last observed
4 March 2026
Residual RMS
0.46 ″
Solution · Otto Matic
5 March 2026

Physical properties

Rotation period
4.65 hours

Visual & observation

Absolute magnitude (H)
14.57

Discovery & classification

Discovered by
Schuster, H.-E.
Discovery date
19 November 1976
Discovery site
La Silla

Named for Orthos, the two-headed dog from Greek mythology. Together with his master Eurytion, this dog looked after the cattle of Geryones. One of the twelve labors of Heracles was to steal these cattle.

Also known as 2329 · 1976 WA

Apollo Near-Earth Object Named

Close approaches 14 on record

Flyby geometry
Ecliptic flyby of Orthos at 2032-09-20 09:23 UTC Top-down view of the ecliptic, Earth at the centre, for the 2032-09-20 09:23 UTC close approach of Orthos. Catalogue miss distance 37.0 LD · 1.42 × 10⁷ km. The curve is the geocentric path from 2032-09-17 to 2032-09-23, with a mark at UTC midnights and an arrow for the direction of motion. The circle is the Moon’s mean orbit; the Moon is plotted at closest approach. A ray shows the Sun’s direction. The labelled distance is the full separation. The drawn radius is the part that lies in the ecliptic plane. At closest approach the object is south of the ecliptic. The path is a geocentric ecliptic ephemeris from JPL Horizons. The inset is a heliocentric view and is approximate. Sun 37.0 LD · 1.42 × 10⁷ km 2032-09-20 09:23 UTC Earth Moon Heliocentric, approximate

Top-down view of the ecliptic, Earth at the centre, for the 2032-09-20 09:23 UTC close approach of Orthos. Catalogue miss distance 37.0 LD · 1.42 × 10⁷ km. The curve is the geocentric path from 2032-09-17 to 2032-09-23, with a mark at UTC midnights and an arrow for the direction of motion. The circle is the Moon’s mean orbit; the Moon is plotted at closest approach. A ray shows the Sun’s direction. The labelled distance is the full separation. The drawn radius is the part that lies in the ecliptic plane. At closest approach the object is south of the ecliptic. The path is a geocentric ecliptic ephemeris from JPL Horizons. The inset is a heliocentric view and is approximate.

JPL Horizons

When (UTC) Body Distance Lunar distances Relative speed
2027-04-14 09:23:00 Juptr 1.7147 AU 667.3 LD 5.8 km/s
2032-09-20 09:23:00 Earth 0.095 AU 37.0 LD 20.2 km/s
2088-09-11 03:23:00 Earth 0.1062 AU 41.3 LD 19.1 km/s
2098-04-16 10:46:00 Juptr 1.7022 AU 662.5 LD 6.5 km/s
2103-09-01 16:12:00 Earth 0.1728 AU 67.3 LD 18.6 km/s
2144-09-02 17:16:00 Earth 0.1653 AU 64.3 LD 18.9 km/s
2157-12-10 00:19:00 Juptr 1.7867 AU 695.3 LD 5.7 km/s
2169-04-08 18:01:00 Juptr 1.8567 AU 722.6 LD 7.5 km/s
2200-09-04 16:26:00 Earth 0.152 AU 59.1 LD 19.2 km/s

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

Sources