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Asteroid Near-Earth

2009 HG21

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(2009 HG21)

Where is it now

Distance from Sun
0.629 AU
True anomaly
312.16°
Distance from Earth
1.147 AU
As of
21 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 — 0.995 AU from the Sun Earth 2009 HG21 — 0.629 AU from the Sun 2009 HG21
Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. 2009 HG21 is 1.147 AU from Earth today (9.5 light-minutes).

In the sky

Right ascension
15h 54m 41s
Declination
-23° 21′ 53″
Constellation
Scorpius
Distance from Earth
1.15 AU
Elongation from the Sun
33.22° — 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
0.908 AU
Eccentricity
0.3679
Inclination
5.43°
Orbital period
315.9 days
Perihelion
0.574 AU
Aphelion
1.242 AU
Longitude of ascending node
32.33°
Argument of periapsis
317.13°
Epoch · J2000
2461200.5
Orbit class · ATE
Aten
Earth MOID · 6.4 LD
0.0165 AU
Tisserand (Jupiter)
6.505

Orbit quality

Orbit poorly determined (uncertainty code 6).

Observations used
27
Data arc
3 days
First observed
20 April 2009
Last observed
23 April 2009
Residual RMS
0.3 ″
Solution · Otto Matic
15 April 2021

Visual & observation

Absolute magnitude (H)
25

Discovery & classification

Aten Near-Earth Object

Close approaches 155 on record

Flyby geometry
Ecliptic flyby of 2009 HG21 at 2027-01-15 10:10 UTC Top-down view of the ecliptic, Earth at the centre, for the 2027-01-15 10:10 UTC close approach of 2009 HG21. Catalogue miss distance 58.1 LD · 2.23 × 10⁷ km. The curve is the geocentric path from 2027-01-12 to 2027-01-18, 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 north of the ecliptic. The path is a geocentric ecliptic ephemeris from JPL Horizons. The inset is a heliocentric view and is approximate. Sun 58.1 LD · 2.23 × 10⁷ km 2027-01-15 10:10 UTC Earth Moon Heliocentric, approximate

Top-down view of the ecliptic, Earth at the centre, for the 2027-01-15 10:10 UTC close approach of 2009 HG21. Catalogue miss distance 58.1 LD · 2.23 × 10⁷ km. The curve is the geocentric path from 2027-01-12 to 2027-01-18, 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 north 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
2027-01-15 10:10:00 Earth 0.1492 AU 58.1 LD 14.6 km/s
2027-09-28 15:41:00 Earth 0.424 AU 165.0 LD 16.1 km/s
2028-04-10 07:00:00 Earth 0.1981 AU 77.1 LD 8.2 km/s
2032-12-15 16:51:00 Venus 0.1259 AU 49.0 LD 9.9 km/s
2033-01-28 16:01:00 Earth 0.4642 AU 180.7 LD 25.3 km/s
2033-11-09 18:43:00 Earth 0.3389 AU 131.9 LD 11 km/s
2034-02-24 19:15:00 Earth 0.2531 AU 98.5 LD 8.8 km/s
2034-08-05 11:00:00 Earth 0.4131 AU 160.8 LD 14.2 km/s
2035-04-26 14:38:00 Earth 0.2322 AU 90.4 LD 18.1 km/s
2037-04-29 17:58:00 Venus 0.0462 AU 18.0 LD 11.9 km/s

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

Sources