SpaceAtlas Space Object Data
NASA JPL SBDB · 2011 EW4

2011 EW4

2011 EW4 belongs to the Apollo group of near-Earth asteroids, whose orbits cross the path of Earth; with a semi-major axis of 1.329 AU it takes 1.53 yr to circle the Sun.

Apollo Observations: 50
Orbital Period · P
1.53 yr
v(q)
38.1 km/s
v(Q)
17.5 km/s
Diameter · ≈
0.09 km
TJ
4.84
Eccentricity · e
0.37

Orbit and dynamics

The path is an ellipse reaching 0.837 AU from the Sun at perihelion and 1.821 AU at aphelion, a radial span of 0.984 AU.

Applying Kepler's third law to a = 1.329 AU gives an orbital period of 1.53 yr, or about 560 days.

An eccentricity of 0.37 makes the orbit moderately elongated.

The orbital plane is tilted 9.75° relative to the ecliptic.

By the vis-viva equation its orbital speed rises to 38.1 km/s at perihelion and falls to 17.5 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 = 23.1 and an assumed geometric albedo of 0.14, the diameter works out to roughly 0.09 km.

Observation record and orbit quality

The current orbit solution is based on 50 observations and has a weighted RMS residual of 0.8619 arcseconds.

Condition code U = 2 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
1.329 AU
Eccentricity
0.37
Perihelion
0.837 AU
Aphelion
1.82073 AU
Inclination
9.75°
Orbital Period
— yr
Epoch
2461200.5
Mean Anomaly
289.4°

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
2031-Mar-11 17:10 0.339097 AU
50728142 km
20.36 km/s
2034-Mar-31 11:42 0.139901 AU
20928937 km
8.72 km/s
2037-Feb-21 15:47 0.467344 AU
69913597 km
8.51 km/s
2037-Jul-26 00:48 0.159848 AU
23912944 km
8.33 km/s
2040-Sep-02 23:41 0.227444 AU
34025095 km
17.62 km/s
2054-Mar-08 11:58 0.407889 AU
61019397 km
22.46 km/s
2057-Mar-27 05:39 0.111379 AU
16662042 km
10.57 km/s
2060-Feb-28 02:00 0.428201 AU
64058026 km
7.94 km/s
2060-Jul-09 05:05 0.197781 AU
29587596 km
8.67 km/s
2063-Sep-01 06:28 0.177058 AU
26487465 km
16.23 km/s
2077-Mar-09 12:29 0.385089 AU
57608518 km
21.75 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
23.1

Orbit Quality

RMS
0.86186
Condition
2
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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