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Asteroid Near-Earth

2021 TR21

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(2021 TR21)

Where is it now

Distance from Sun
0.86 AU
True anomaly
256.16°
Distance from Earth
1.32 AU
As of
19 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 — 0.996 AU from the Sun Earth 2021 TR21 — 0.86 AU from the Sun 2021 TR21
Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. 2021 TR21 is 1.32 AU from Earth today (11.0 light-minutes).

In the sky

Right ascension
11h 08m 29s
Declination
+04° 10′ 32″
Constellation
Leo
Distance from Earth
1.32 AU
Elongation from the Sun
40.51° — 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
0.853 AU
Eccentricity
0.2038
Inclination
2.08°
Orbital period
287.8 days
Perihelion
0.679 AU
Aphelion
1.027 AU
Longitude of ascending node
230.95°
Argument of periapsis
349.62°
Epoch · J2000
2461200.5
Orbit class · ATE
Aten
Earth MOID · 5.2 LD
0.0133 AU
Tisserand (Jupiter)
6.892

Orbit quality

Orbit poorly determined (uncertainty code 7).

Observations used
29
Data arc
17 days
First observed
15 October 2021
Last observed
1 November 2021
Residual RMS
0.66 ″
Solution · Otto Matic
1 November 2021

Visual & observation

Absolute magnitude (H)
26.36

Discovery & classification

Aten Near-Earth Object

Close approaches 43 on record

Flyby geometry
Ecliptic flyby of 2021 TR21 at 2032-10-03 00:14 UTC Top-down view of the ecliptic, Earth at the centre, for the 2032-10-03 00:14 UTC close approach of 2021 TR21. Catalogue miss distance 87.7 LD · 3.37 × 10⁷ km. The curve is the geocentric path from 2032-09-30 to 2032-10-06, 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 87.7 LD · 3.37 × 10⁷ km 2032-10-03 00:14 UTC Earth Moon Heliocentric, approximate

Top-down view of the ecliptic, Earth at the centre, for the 2032-10-03 00:14 UTC close approach of 2021 TR21. Catalogue miss distance 87.7 LD · 3.37 × 10⁷ km. The curve is the geocentric path from 2032-09-30 to 2032-10-06, 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
2032-10-03 00:14:00 Earth 0.2252 AU 87.7 LD 11.8 km/s
2040-12-06 23:27:00 Earth 0.2667 AU 103.8 LD 13.2 km/s
2043-10-12 16:32:00 Earth 0.4869 AU 189.5 LD 20.2 km/s
2047-10-01 16:24:00 Earth 0.1447 AU 56.3 LD 9.2 km/s
2051-08-08 08:34:00 Earth 0.2108 AU 82.0 LD 3.3 km/s
2051-12-09 05:32:00 Earth 0.029 AU 11.3 LD 5.3 km/s
2053-01-30 22:53:00 Venus 0.117 AU 45.5 LD 11.4 km/s
2055-05-26 09:46:00 Earth 0.3254 AU 126.6 LD 9.8 km/s
2055-12-01 19:06:00 Earth 0.4257 AU 165.7 LD 18.3 km/s
2058-10-05 18:37:00 Earth 0.2888 AU 112.4 LD 13.8 km/s

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

Sources