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Asteroid Near-Earth Potentially hazardous

363505

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363505 (2003 UC20)

Where is it now

Distance from Sun
0.994 AU
True anomaly
205.79°
Distance from Earth
1.15 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 363505 — 0.994 AU from the Sun 363505
Seen from above the ecliptic, north up, to scale. Grid: Earth's orbit in blue. 363505 is 1.15 AU from Earth today (9.6 light-minutes).

In the sky

Right ascension
10h 00m 42s
Declination
+08° 41′ 45″
Constellation
Leo
Distance from Earth
1.15 AU
Elongation from the Sun
54.61° — 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
0.781 AU
Eccentricity
0.3369
Inclination
3.78°
Orbital period
252.2 days
Perihelion
0.518 AU
Aphelion
1.044 AU
Longitude of ascending node
187.92°
Argument of periapsis
60.17°
Epoch · J2000
2461200.5
Orbit class · ATE
Aten
Earth MOID · 13.7 LD
0.0353 AU
Tisserand (Jupiter)
7.388

Orbit quality

Orbit very well determined (uncertainty code 0).

Observations used
1,075
Data arc
71.82 years
First observed
5 December 1954
Last observed
2 October 2026
Residual RMS
0.49 ″
Solution · Otto Matic
3 October 2026

Physical properties

Mean radius
0.94 km
Rotation period
29.6 hours

Visual & observation

Geometric albedo
0.029
Absolute magnitude (H)
18.48

Discovery & classification

Discovered by
LINEAR
Discovery date
21 October 2003
Discovery site
Socorro

Also known as 2003 UC20 · 1954 XA

Aten Near-Earth Object Potentially Hazardous Asteroid

Close approaches 171 on record

Flyby geometry
Ecliptic flyby of 363505 at 2032-12-01 02:06 UTC Top-down view of the ecliptic, Earth at the centre, for the 2032-12-01 02:06 UTC close approach of 363505. Catalogue miss distance 32.2 LD · 1.24 × 10⁷ km. The curve is the geocentric path from 2032-11-28 to 2032-12-04, 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 32.2 LD · 1.24 × 10⁷ km 2032-12-01 02:06 UTC Earth Moon Heliocentric, approximate

Top-down view of the ecliptic, Earth at the centre, for the 2032-12-01 02:06 UTC close approach of 363505. Catalogue miss distance 32.2 LD · 1.24 × 10⁷ km. The curve is the geocentric path from 2032-11-28 to 2032-12-04, 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
2027-08-18 13:44:00 Venus 0.0939 AU 36.5 LD 15.3 km/s
2032-12-01 02:06:00 Earth 0.0827 AU 32.2 LD 6.5 km/s
2033-12-09 20:53:00 Merc 0.0875 AU 34.1 LD 15.1 km/s
2033-12-09 20:53:00 Mercury 0.0875 AU 34.1 LD 15.1 km/s
2034-10-01 07:55:00 Venus 0.1468 AU 57.1 LD 18.7 km/s
2040-04-11 05:32:00 Venus 0.0708 AU 27.6 LD 14.1 km/s
2041-12-30 18:51:00 Earth 0.0667 AU 25.9 LD 8.2 km/s
2043-10-31 13:13:00 Earth 0.1285 AU 50.0 LD 12 km/s
2044-04-18 15:39:00 Mercury 0.0862 AU 33.5 LD 14.9 km/s
2044-04-18 15:39:00 Merc 0.0862 AU 33.5 LD 14.9 km/s

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

Sources