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Asteroid Near-Earth Potentially hazardous

308242

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308242 (2005 GO21)

Where is it now

Distance from Sun
1.009 AU
True anomaly
181.73°
Distance from Earth
1.817 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 308242 — 1.009 AU from the Sun 308242
Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. 308242 is 1.817 AU from Earth today (15.1 light-minutes).

In the sky

Right ascension
14h 57m 25s
Declination
-21° 59′ 33″
Constellation
Libra
Distance from Earth
1.82 AU
Elongation from the Sun
25.2° — near the Sun — look low at dusk or dawn

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
0.753 AU
Eccentricity
0.3399
Inclination
24.93°
Orbital period
238.8 days
Perihelion
0.497 AU
Aphelion
1.009 AU
Longitude of ascending node
272.67°
Argument of periapsis
156.65°
Epoch · J2000
2461200.5
Orbit class · ATE
Aten
Earth MOID · 17.1 LD
0.044 AU
Tisserand (Jupiter)
7.557

Orbit quality

Orbit very well determined (uncertainty code 0).

Observations used
557
Data arc
20.42 years
First observed
1 April 2005
Last observed
31 August 2025
Residual RMS
0.3 ″
Solution · Otto Matic
16 June 2026

Physical properties

Rotation period
11 hours

Visual & observation

Absolute magnitude (H)
16.18

Discovery & classification

Discovered by
Siding Spring Survey
Discovery date
1 April 2005
Discovery site
Siding Spring

Also known as 2005 GO21

Aten Near-Earth Object Potentially Hazardous Asteroid

Close approaches 31 on record

Flyby geometry
Ecliptic flyby of 308242 at 2027-06-20 05:52 UTC Top-down view of the ecliptic, Earth at the centre, for the 2027-06-20 05:52 UTC close approach of 308242. Catalogue miss distance 76.4 LD · 2.94 × 10⁷ km. The curve is the geocentric path from 2027-06-17 to 2027-06-23, 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 76.4 LD · 2.94 × 10⁷ km 2027-06-20 05:52 UTC Earth Moon Heliocentric, approximate

Top-down view of the ecliptic, Earth at the centre, for the 2027-06-20 05:52 UTC close approach of 308242. Catalogue miss distance 76.4 LD · 2.94 × 10⁷ km. The curve is the geocentric path from 2027-06-17 to 2027-06-23, 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
2027-06-20 05:52:00 Earth 0.1962 AU 76.4 LD 12.8 km/s
2029-06-21 23:02:00 Earth 0.0465 AU 18.1 LD 13.5 km/s
2044-06-20 08:11:00 Earth 0.1685 AU 65.6 LD 12.6 km/s
2046-06-21 22:09:00 Earth 0.0636 AU 24.8 LD 13.9 km/s
2061-06-21 15:43:00 Earth 0.123 AU 47.9 LD 12.5 km/s
2063-06-21 10:05:00 Earth 0.1074 AU 41.8 LD 14.8 km/s
2078-06-22 12:12:00 Earth 0.0778 AU 30.3 LD 12.7 km/s
2080-06-19 14:37:00 Earth 0.1566 AU 60.9 LD 15.9 km/s
2095-06-22 21:20:00 Earth 0.051 AU 19.8 LD 13 km/s
2097-06-19 00:02:00 Earth 0.1916 AU 74.6 LD 16.7 km/s

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

Sources