Illustration of Earth with several asteroids passing at different distances, one flagged as potentially hazardous

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(2018 EL4)

Designation: 2018 EL4 · NASA id: 3801935 · Sentry Object

Estimated diameter: 23 – 51 meters

≈ an airliner's wingspan
That comparison is of size only — what an impact would do depends on speed, angle, composition and where it arrives, none of which follows from width.
(absolute magnitude H = 25.35) · JPL Small-Body Database →

Earth impact concern
On a monitored risk list
Why?
  • Its closest recorded pass was 5.9 lunar distances.
  • It is on the Sentry list, which holds every object with a computed chance above zero — 2,207 of them. Being listed is not by itself a warning.
  • The computed chance is about 1 in 25,006,252, over the window 2120.
  • Palermo -7.98 — below zero, meaning less than the background risk from everything not yet found.
  • Torino 0.
What the four levels mean
  • No identified impact threat — not on any risk list. 98.8% of the objects here.
  • On a monitored risk list — a computed chance above zero, however small. 1.2% of the objects here.
  • Among the highest-ranked — Palermo at or above −2. Two objects worldwide qualify, both studied for decades and both centuries away.
  • Exceptional — Torino 1 or more, or Palermo at or above zero. No object anywhere currently qualifies.

These describe where an object sits in a catalogue, not how dangerous it is. The full ranked list is on the impact risk page.

Energy of motion, if it ever entered the atmosphere

46 kilotonnes – 1.7 megatonnes of TNT

This is not a forecast. Nothing here says this object will arrive, and almost nothing ever does — what is actually assessed, by people with far better data than this page has, is on the impact risk page. This is simply the kinetic energy such a body would carry, worked out from its size and its usual encounter speed.

The range spans a factor of 37, and it cannot be narrowed. Nobody has weighed this object. Its diameter is inferred from how bright it is under an assumed reflectivity, which carries a fixed factor of 2.24 — and because mass goes as the cube of diameter, that alone becomes a factor of 11. Density is then assumed somewhere between 1,500 and 5,000 kg/m³, from a loose rubble pile to dense rock. Quoting a tighter figure would be invented precision.

Megatonnes do not mean what the word suggests here. Most of this energy is spent high in the atmosphere, not on the ground, and the comparison with weapons misleads badly. The Chelyabinsk body released around 440 kilotonnes in 2013 — this same calculation gives it 166 to 904 — and the damage was broken windows across a city, from the shock wave of an airburst some thirty kilometres up. No crater, and nothing that reached the ground intact.

Why is one asteroid “hazardous” when closer ones are not?

Because the flag has nothing to do with how close it came on the day. NASA marks an object a Potentially Hazardous Asteroid only if both of these are true of its orbit and its size:

  • Its orbit can bring it within 0.05 AU of Earth’s — about 7.5 million km. This is the Minimum Orbit Intersection Distance, the closest the two paths ever come, not the distance on any given pass.
  • It is big enough to matter — absolute magnitude 22.0 or brighter, which is roughly 140 metres across and up. That threshold is a planning convention, not a physical boundary: it is about the size at which an impact could do regional damage. Smaller objects are not harmless, they are simply outside this definition — the Chelyabinsk object of 2013 was around 20 metres and injured about 1,500 people with the shock wave from its airburst, without ever reaching the ground intact.

The two terms: AU — astronomical unit, the average Earth–Sun distance, 149,597,871 km. 0.05 AU is about 7.5 million km.
MOID — minimum orbit intersection distance, the closest the two orbits ever come, whatever the timing. See the glossary for NEO, PHA and H.

So a large rock passing at 39 million km today can be flagged, because on some future orbit it could come far nearer — while a pebble skimming past at 4 million km is not, because it would never reach the ground.

Three objects that all passed Earth on 30 August 2026 make the point better than any definition:

Object Size Orbit’s closest to Earth’s Missed by, that day Flagged
2013 JR28 122–272 m 5.3 M km (0.035 AU) 39.2 M km Yes — both tests pass
2012 LE11 629–1,406 m 23.3 M km (0.156 AU) 26.1 M km No — orbit never gets near enough
2007 EK 3.7–8.2 m 198,000 km (0.0013 AU) 4.2 M km No — far too small

The middle one is five times larger than the flagged one and passed closer on the day, but its path can never come within 23 million km of ours. The last one’s orbit crosses inside the Moon’s distance — nearer than any other object here — and it is still not hazardous, because at a few metres across it would burn up long before it landed.

“Potentially hazardous” is a watchlist criterion, not a prediction. None of these is on a collision course; the label means an object is worth keeping precise track of over the coming centuries.

Orbital Data

Orbit class: APO — Near-Earth asteroid orbits which cross the Earth’s orbit similar to that of 1862 Apollo
a (semi-major axis) > 1.0 AU; q (perihelion) < 1.017 AU

Orbital period400.8 days (1.10 years)
Eccentricity.197301217227059 (0 = circular, closer to 1 = more elongated)
Semi-major axis1.063949606674582 AU
Inclination3.182154369163331° (tilt of its orbit vs. Earth's)
Perihelion distance.8540310542094365 AU (closest approach to the Sun)
Aphelion distance1.273868159139728 AU (farthest from the Sun)
Minimum Orbit Intersection Distance0.00550 AU = 822,953 km
(closest its orbit path ever comes to Earth's, regardless of timing)
Ascending node longitude168.4901723235011°
Argument of perihelion271.030352445043°
Mean anomaly / motion72.13913803051891° / .8980954297939847°/day
Jupiter Tisserand invariant5.776 (helps distinguish asteroids from comets)
Reference epoch / equinoxJD 2461000.5 / J2000
Orbit determined2021-04-15 20:24:14
Observed2018-03-14 to 2018-04-13 (30 day arc, 85 observations used)
Orbit uncertainty5 (0 = best known, 9 = least certain)

Close Approach History

Every close approach NASA has on record for this object — 40 total.

Why does it pass Earth and Venus? Doesn’t it orbit just one?

It orbits the Sun. Not Earth, and not Venus. The column above does not say what the asteroid goes around — it says which planet a given close approach was to. 38 of them were approaches to Earth and 2 of them were approaches to Venus.

This one’s path runs from 0.854 AU at its closest to the Sun out to 1.274 AU at its farthest. For scale, Venus orbits at about 0.72 AU and Earth at 1.00 AU — so an orbit spanning that range crosses the path of every planet in between, once on the way out and once on the way back.

Crossing a planet’s path is not the same as meeting the planet. Almost every time the asteroid crosses, that planet is somewhere else along its own orbit. A close approach is logged only on the rare occasions when both happen to arrive at the crossing point at roughly the same time — which is why the dates below are scattered rather than regular. This object takes 400.8 days to go round, against Earth’s 365.25, so the two drift in and out of step over years rather than repeating on a neat cycle.

The Minimum Orbit Intersection Distance in the table above (0.0055 AU) is the closest the two paths ever come. The miss distances below are how far apart the two bodies actually were on the day, which is almost always very much larger.

next approach: 2027-09-04

Date Passed near Velocity (km/h) Miss distance
2087-03-02 Earth 17918.72 3,334,966 km
8.68 LD
2085-09-12 Earth 30318.87 14,739,314 km
38.3 LD
2076-03-22 Earth 60285.71 56,570,040 km
147 LD
2073-09-02 Earth 50701.88 43,762,977 km
114 LD
2064-03-12 Earth 38341.17 25,915,572 km
67.4 LD
2061-08-24 Earth 70965.32 72,385,877 km
188 LD
2052-03-06 Earth 24324.33 6,003,044 km
15.6 LD
2051-06-08 Earth 20284.73 38,832,928 km
101 LD
2050-09-16 Earth 21627.27 2,267,459 km
5.90 LD
2041-03-15 Earth 49311.26 41,233,171 km
107 LD
2040-05-06 Earth 18688.09 35,460,979 km
92.3 LD
2039-11-09 Earth 16325.76 18,941,446 km
49.3 LD
2039-08-21 Earth 12367.57 23,579,452 km
61.3 LD
2038-08-25 Earth 66296.29 65,759,543 km
171 LD
2030-03-25 Earth 69847.80 69,875,912 km
182 LD
2029-03-20 Earth 11159.52 21,123,679 km
55.0 LD
2029-01-14 Earth 15452.68 17,786,640 km
46.3 LD
2028-07-08 Earth 18793.11 36,359,392 km
94.6 LD
2027-09-04 next Earth 46195.00 37,456,844 km
97.4 LD
2025-08-25 Venus 8769.18 20,998,279 km
54.6 LD
2018-03-03 Earth 22878.46 4,086,550 km
10.6 LD
2017-06-10 Earth 20288.63 39,251,504 km
102 LD
2016-09-11 Earth 25610.81 8,077,365 km
21.0 LD
2007-03-19 Earth 56776.81 51,604,653 km
134 LD
2006-04-21 Earth 16698.09 31,028,633 km
80.7 LD
2005-12-07 Earth 18140.72 21,111,747 km
54.9 LD
2005-07-27 Earth 16185.71 30,822,636 km
80.2 LD
2004-08-28 Earth 56165.77 51,571,198 km
134 LD
1995-03-04 Earth 25611.66 7,910,603 km
20.6 LD
1994-06-06 Earth 20388.54 39,242,102 km
102 LD
1993-09-13 Earth 22989.65 4,148,749 km
10.8 LD
1990-07-28 Venus 9242.29 21,180,248 km
55.1 LD
1984-03-13 Earth 47856.73 39,149,371 km
102 LD
1983-05-07 Earth 18952.60 35,937,941 km
93.5 LD
1981-08-22 Earth 67410.11 67,353,352 km
175 LD
1973-03-23 Earth 69318.06 69,121,030 km
180 LD
1970-09-01 Earth 46457.34 37,788,109 km
98.3 LD
1961-03-01 Earth 23428.67 4,921,798 km
12.8 LD
1960-06-07 Earth 20326.66 39,357,009 km
102 LD
1959-09-11 Earth 25627.01 8,081,570 km
21.0 LD

Looked up from NASA's NeoWs API and cached — last refreshed 2026-09-05T23:04:57.569450+00:00.