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

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5143 Heracles (1991 VL)

Designation: 5143 · NASA id: 2005143

Estimated diameter: 4,136 – 9,248 meters

≈ more than a kilometre across
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 = 14.04) · JPL Small-Body Database →

Earth impact concern
No identified impact threat
Why?
  • Its closest recorded pass was 18.8 lunar distances.
  • It is not on NASA/JPL’s Sentry list, which holds every object with a computed chance of impact above zero. Most objects are not on it.
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

3,687,820 megatonnes – 137,436,949 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 period907.7 days (2.49 years)
Eccentricity.7712670666718562 (0 = circular, closer to 1 = more elongated)
Semi-major axis1.834647992353865 AU
Inclination8.978847882791301° (tilt of its orbit vs. Earth's)
Perihelion distance.4196444169156895 AU (closest approach to the Sun)
Aphelion distance3.249651567792041 AU (farthest from the Sun)
Minimum Orbit Intersection Distance0.05750 AU = 8,601,937 km
(closest its orbit path ever comes to Earth's, regardless of timing)
Ascending node longitude309.0953620330217°
Argument of perihelion228.2124805913949°
Mean anomaly / motion283.437987573902° / .396620309341545°/day
Jupiter Tisserand invariant3.583 (helps distinguish asteroids from comets)
Reference epoch / equinoxJD 2461200.5 / J2000
Orbit determined2026-09-01 06:20:55
Observed1953-11-30 to 2026-08-31 (26572 day arc, 5291 observations used)
Orbit uncertainty0 (0 = best known, 9 = least certain)

Close Approach History

Every close approach NASA has on record for this object — 43 total.

Why does it pass Venus, Earth, Merc, Juptr and Mars? 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. 14 of them were approaches to Venus, 12 of them were approaches to Earth, 8 of them were approaches to Merc, 6 of them were approaches to Juptr and 3 of them were approaches to Mars.

This one’s path runs from 0.420 AU at its closest to the Sun out to 3.250 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 907.7 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 (0.0575 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: 2029-05-18

Date Passed near Velocity (km/h) Miss distance
2193-07-08 Earth 81517.71 16,426,331 km
42.7 LD
2188-07-16 Earth 99217.43 10,873,422 km
28.3 LD
2178-07-22 Venus 97181.95 7,904,365 km
20.6 LD
2170-11-30 Earth 100358.08 20,490,499 km
53.3 LD
2164-10-31 Juptr 21261.92 272,212,691 km
708 LD
2163-07-08 Venus 76807.94 21,658,674 km
56.3 LD
2161-01-11 Venus 99936.59 7,207,938 km
18.8 LD
2138-12-15 Mars 88292.01 8,314,671 km
21.6 LD
2136-04-17 Merc 70295.94 11,943,134 km
31.1 LD
2117-08-08 Juptr 22099.79 275,271,686 km
716 LD
2116-07-11 Earth 90236.16 7,647,526 km
19.9 LD
2111-07-06 Venus 110988.42 14,105,514 km
36.7 LD
2109-01-11 Venus 85550.83 14,530,414 km
37.8 LD
2103-12-28 Merc 59176.27 13,479,583 km
35.1 LD
2096-07-23 Merc 82699.34 12,957,339 km
33.7 LD
2093-12-21 Venus 99172.03 8,027,479 km
20.9 LD
2093-12-04 Earth 89503.02 19,135,616 km
49.8 LD
2058-01-12 Juptr 21403.19 272,945,793 km
710 LD
2056-10-21 Merc 63252.83 12,662,502 km
32.9 LD
2044-07-01 Earth 73329.20 28,534,066 km
74.2 LD
2044-06-10 Venus 100213.05 10,604,976 km
27.6 LD
2039-07-10 Earth 91068.80 8,639,064 km
22.5 LD
2034-07-18 Earth 109034.85 25,052,682 km
65.2 LD
2029-05-18 next Venus 96729.58 8,866,003 km
23.1 LD
2016-11-28 Earth 98579.84 21,993,467 km
57.2 LD
2010-10-14 Juptr 21959.61 271,920,095 km
707 LD
2009-08-07 Merc 63734.80 12,827,006 km
33.4 LD
2007-04-18 Mars 91105.25 11,463,380 km
29.8 LD
1979-11-08 Venus 108151.48 14,582,482 km
37.9 LD
1977-05-14 Venus 77598.68 20,766,722 km
54.0 LD
1969-11-10 Merc 64217.14 13,058,618 km
34.0 LD
1964-10-19 Venus 82055.81 17,714,552 km
46.1 LD
1962-07-07 Earth 84843.94 14,938,089 km
38.9 LD
1962-04-23 Venus 111931.66 15,588,104 km
40.6 LD
1957-07-17 Earth 107890.87 24,011,745 km
62.5 LD
1951-03-22 Juptr 21625.46 274,202,731 km
713 LD
1945-03-18 Mars 83055.23 8,133,151 km
21.2 LD
1939-12-01 Earth 92979.82 21,647,720 km
56.3 LD
1930-02-04 Merc 58521.51 13,711,524 km
35.7 LD
1922-08-31 Merc 78878.47 14,009,682 km
36.4 LD
1915-04-03 Venus 105649.61 13,991,413 km
36.4 LD
1912-10-09 Venus 79984.14 19,837,077 km
51.6 LD
1903-12-22 Juptr 21807.35 270,323,269 km
703 LD

Looked up from NASA's NeoWs API and cached — last refreshed 2026-09-02T14:14:51.820000+00:00.