SpaceAtlas Space Object Data
NASA JPL SBDB · 2011 UR91

2011 UR91

2011 UR91 belongs to the Apollo group of near-Earth asteroids, whose orbits cross the path of Earth; with a semi-major axis of 1.716 AU it takes 2.25 yr to circle the Sun.

Apollo Observations: 45
Orbital Period · P
2.25 yr
v(q)
39.8 km/s
v(Q)
13 km/s
Diameter · ≈
0.05 km
TJ
3.91
Eccentricity · e
0.5072

Orbit and dynamics

Between its closest point (0.846 AU) and its farthest (2.586 AU), the heliocentric distance changes by 1.74 AU over every revolution.

One full revolution takes 2.25 yr (821 days), computed from the semi-major axis of 1.716 AU.

The high eccentricity (0.507) produces a strongly elongated orbit, so the object spends most of its time far from the Sun.

A steep inclination of 27.76° carries it well above and below the ecliptic plane.

By the vis-viva equation its orbital speed rises to 39.8 km/s at perihelion and falls to 13 km/s at aphelion.

Because q < 1 AU and Q > 1 AU, this orbit geometrically intersects the region of Earth's orbit.

Size and surface

No direct size measurement is available; from an absolute magnitude of H = 24.3 and an assumed geometric albedo of 0.14, the diameter works out to roughly 0.05 km.

Observation record and orbit quality

Astrometry from 45 individual observations underpins this orbit; the fit leaves an RMS residual of 0.46 arcseconds.

Condition code U = 0 means the orbit is very well determined, leaving only a small uncertainty in the future ephemeris.

About these computed values

Orbital periods, perihelion and aphelion speeds, and diameter estimates on this page are computed by SpaceAtlas from the JPL SBDB orbital elements. They are derived quantities, not values copied from the source catalogue.

Orbital Parameters

Semi-Major Axis
1.716 AU
Eccentricity
0.5072
Perihelion
0.846 AU
Aphelion
2.586355 AU
Inclination
27.76°
Orbital Period
— yr
Epoch
2461200.5
Mean Anomaly
209.15°

Orbit diagram

The Sun sits at the focus (orange). Earth's orbit is the grey circle at 1 AU. The red dot marks the object's position at the catalog epoch.

3D orbit (interactive)

Drag to rotate; scroll or pinch to zoom. The Sun is at the focus (orange), Earth's orbit is the grey ring at 1 AU, and the red dot marks the object's current position.

Close approaches

Predicted close approaches to Earth, from NASA's Center for Near-Earth Object Studies (CNEOS).

Date (UTC)Miss distanceVelocity
2029-Oct-11 04:17 0.185378 AU
27732084 km
16.84 km/s
2038-Oct-08 22:33 0.251091 AU
37562712 km
15.77 km/s
2047-May-13 08:32 0.450977 AU
67465216 km
14.31 km/s
2047-Oct-07 03:16 0.318593 AU
47660847 km
14.94 km/s
2056-May-13 23:05 0.396790 AU
59359007 km
14.69 km/s
2056-Oct-04 18:56 0.392085 AU
58655090 km
14.34 km/s
2065-May-14 23:58 0.342570 AU
51247668 km
15.33 km/s
2065-Oct-04 15:53 0.470043 AU
70317489 km
13.98 km/s
2074-May-15 03:29 0.296056 AU
44289363 km
16.34 km/s

Distances in astronomical units (AU) and kilometres. Source: NASA/JPL CNEOS Close Approach Data API.

Physical Parameters

Diameter
— km
Albedo
—
Density
— g/cm³
Rotation Period
— h
Absolute Magnitude
24.3

Orbit Quality

RMS
0.45995
Condition
0
Orbit ID
—
Data source: NASA JPL Small-Body Database · NASA CNEOS. Orbital periods, perihelion and aphelion speeds, and diameter estimates on this page are computed by SpaceAtlas from the JPL SBDB orbital elements. They are derived quantities, not values copied from the source catalogue.

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