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Asteroid Near-Earth Potentially hazardous

Tantalus

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2102 Tantalus (1975 YA)

Where is it now

Distance from Sun
1.654 AU
True anomaly
194.42°
Distance from Earth
1.602 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.

Sun Earth — 0.998 AU from the Sun Earth Tantalus — 1.654 AU from the Sun Tantalus
Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. Tantalus is 1.602 AU from Earth today (13.3 light-minutes).

In the sky

Right ascension
12h 40m 16s
Declination
-82° 18′ 02″
Constellation
Chamaeleon
Distance from Earth
1.6 AU
Elongation from the Sun
74.9° — 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
1.29 AU
Eccentricity
0.2994
Inclination
64°
Orbital period
535.2 days
Perihelion
0.904 AU
Aphelion
1.676 AU
Longitude of ascending node
94.35°
Argument of periapsis
61.51°
Epoch · J2000
2461200.5
Orbit class · APO
Apollo
Earth MOID · 16.6 LD
0.0426 AU
Tisserand (Jupiter)
4.45

Orbit quality

Orbit very well determined (uncertainty code 0).

Observations used
2,349
Data arc
50.6 years
First observed
2 January 1976
Last observed
8 August 2026
Residual RMS
0.4 ″
Solution · Otto Matic
8 August 2026

Physical properties

Mean radius
0.82 km
Rotation period
2.38 hours

Visual & observation

Geometric albedo
0.245
Absolute magnitude (H)
15.99
Spectral type (SMASS)
Q

Discovery & classification

Discovered by
Kowal, C. T.
Discovery date
27 December 1975
Discovery site
Palomar

Also known as 2102 · 1975 YA

Apollo Near-Earth Object Named Potentially Hazardous Asteroid

Close approaches 19 on record

Flyby geometry
Ecliptic flyby of Tantalus at 2038-12-27 07:34 UTC Top-down view of the ecliptic, Earth at the centre, for the 2038-12-27 07:34 UTC close approach of Tantalus. Catalogue miss distance 17.3 LD · 6.64 × 10⁶ km. The curve is the geocentric path from 2038-12-24 to 2038-12-30, 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. The path is a geocentric ecliptic ephemeris from JPL Horizons. The inset is a heliocentric view and is approximate. Sun 25 Dec 30 Dec 17.3 LD · 6.64 × 10⁶ km 2038-12-27 07:34 UTC Earth Moon Heliocentric, approximate

Top-down view of the ecliptic, Earth at the centre, for the 2038-12-27 07:34 UTC close approach of Tantalus. Catalogue miss distance 17.3 LD · 6.64 × 10⁶ km. The curve is the geocentric path from 2038-12-24 to 2038-12-30, 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. 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
2038-12-27 07:34:00 Earth 0.0444 AU 17.3 LD 33.4 km/s
2060-12-23 07:04:00 Earth 0.0991 AU 38.6 LD 34.3 km/s
2067-05-03 05:59:00 Mars 0.0825 AU 32.1 LD 26.5 km/s
2080-01-02 02:57:00 Earth 0.1799 AU 70.0 LD 32.6 km/s
2080-07-05 19:42:00 Mars 0.0691 AU 26.9 LD 27.2 km/s
2101-12-29 20:23:00 Earth 0.0704 AU 27.4 LD 33.2 km/s
2123-12-27 06:36:00 Earth 0.0521 AU 20.3 LD 33.8 km/s
2145-12-22 14:41:00 Earth 0.1579 AU 61.5 LD 34.9 km/s
2164-12-31 14:58:00 Earth 0.1154 AU 44.9 LD 32.9 km/s
2186-12-28 09:07:00 Earth 0.037 AU 14.4 LD 33.6 km/s

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

Sources