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Asteroid Near-Earth

2021 RA4

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(2021 RA4)

Where is it now

Distance from Sun
1.083 AU
True anomaly
150.85°
Distance from Earth
0.683 AU
As of
20 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 RA4 — 1.083 AU from the Sun 2021 RA4
Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. 2021 RA4 is 0.683 AU from Earth today (5.7 light-minutes).

In the sky

Right ascension
19h 10m 17s
Declination
-24° 52′ 38″
Constellation
Sagittarius
Distance from Earth
0.69 AU
Elongation from the Sun
77.91° — 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
0.897 AU
Eccentricity
0.2618
Inclination
17.66°
Orbital period
310.1 days
Perihelion
0.662 AU
Aphelion
1.131 AU
Longitude of ascending node
165.01°
Argument of periapsis
33.65°
Epoch · J2000
2461200.5
Orbit class · ATE
Aten
Earth MOID · 19.0 LD
0.0487 AU
Tisserand (Jupiter)
6.567

Orbit quality

Orbit reasonably well determined (uncertainty code 5).

Observations used
41
Data arc
16 days
First observed
8 September 2021
Last observed
24 September 2021
Residual RMS
0.36 ″
Solution · Otto Matic
24 September 2021

Visual & observation

Absolute magnitude (H)
24.32

Discovery & classification

Aten Near-Earth Object

Close approaches 128 on record

Flyby geometry
Ecliptic flyby of 2021 RA4 at 2027-06-03 13:57 UTC Top-down view of the ecliptic, Earth at the centre, for the 2027-06-03 13:57 UTC close approach of 2021 RA4. Catalogue miss distance 153.1 LD · 5.89 × 10⁷ km. The curve is the geocentric path from 2027-05-31 to 2027-06-06, 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. 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 153.1 LD · 5.89 × 10⁷ km 2027-06-03 13:57 UTC Earth Moon Heliocentric, approximate

Top-down view of the ecliptic, Earth at the centre, for the 2027-06-03 13:57 UTC close approach of 2021 RA4. Catalogue miss distance 153.1 LD · 5.89 × 10⁷ km. The curve is the geocentric path from 2027-05-31 to 2027-06-06, 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. 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
2027-06-03 13:57:00 Earth 0.3935 AU 153.1 LD 8.8 km/s
2027-10-04 00:59:00 Earth 0.2473 AU 96.2 LD 9.6 km/s
2028-01-29 16:29:00 Earth 0.269 AU 104.7 LD 12.5 km/s
2032-09-02 06:06:00 Earth 0.2207 AU 85.9 LD 15.7 km/s
2033-04-11 01:03:00 Earth 0.3725 AU 145.0 LD 14.6 km/s
2033-12-10 17:15:00 Earth 0.3533 AU 137.5 LD 14.2 km/s
2038-09-08 01:08:00 Earth 0.1036 AU 40.3 LD 9.8 km/s
2039-02-28 10:13:00 Earth 0.2979 AU 115.9 LD 14.2 km/s
2043-09-09 02:04:00 Earth 0.4272 AU 166.3 LD 21.6 km/s
2044-04-12 20:38:00 Venus 0.0473 AU 18.4 LD 13.2 km/s

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

Sources