SpaceAtlas Space Object Data
NASA JPL SBDB · 1998 EP4

1998 EP4

1998 EP4 belongs to the Apollo group of near-Earth asteroids, whose orbits cross the path of Earth; with a semi-major axis of 1.56 AU it takes 1.95 yr to circle the Sun.

Apollo Observations: 71
Orbital Period · P
1.95 yr
v(q)
38.3 km/s
v(Q)
14.8 km/s
Diameter · ≈
0.18 km
TJ
4.31
Eccentricity · e
0.4412

Orbit and dynamics

Between its closest point (0.872 AU) and its farthest (2.248 AU), the heliocentric distance changes by 1.376 AU over every revolution.

One full revolution takes 1.95 yr (712 days), computed from the semi-major axis of 1.56 AU.

The high eccentricity (0.441) produces a strongly elongated orbit, so the object spends most of its time far from the Sun.

The orbital plane is tilted 7.19° relative to the ecliptic.

By the vis-viva equation its orbital speed rises to 38.3 km/s at perihelion and falls to 14.8 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 = 21.5 and an assumed geometric albedo of 0.14, the diameter works out to roughly 0.18 km.

Observation record and orbit quality

Astrometry from 71 individual observations underpins this orbit; the fit leaves an RMS residual of 0.5946 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
1.56 AU
Eccentricity
0.4412
Perihelion
0.872 AU
Aphelion
2.248272 AU
Inclination
7.19°
Orbital Period
— yr
Epoch
2461200.5
Mean Anomaly
140.48°

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-Aug-27 11:34 0.228515 AU
34185352 km
17.65 km/s
2033-Mar-21 17:56 0.492005 AU
73602909 km
5.55 km/s
2033-Jul-31 09:18 0.117556 AU
17586085 km
8.85 km/s
2035-May-02 04:50 0.137671 AU
20595226 km
8.44 km/s
2037-Mar-29 19:42 0.192076 AU
28734150 km
16.70 km/s
2068-Sep-05 01:16 0.402329 AU
60187620 km
22.81 km/s
2070-Aug-19 12:55 0.106555 AU
15940339 km
13.69 km/s
2072-Jun-25 00:49 0.181721 AU
27185142 km
8.85 km/s
2074-Apr-12 21:12 0.066282 AU
9915610 km
10.96 km/s
2076-Mar-23 23:53 0.304973 AU
45623280 km
20.08 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
21.5

Orbit Quality

RMS
0.59463
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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