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

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(2002 TH68)

Designation: 2002 TH68 · NASA id: 3137848

Estimated diameter: 120 – 269 meters

≈ the Great Pyramid
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 = 21.72) · JPL Small-Body Database →

Earth impact concern
No identified impact threat
Why?
  • Its closest recorded pass was 34.5 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

21.8 megatonnes – 811.2 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: AMO — Near-Earth asteroid orbits similar to that of 1221 Amor
1.017 AU < q (perihelion) < 1.3 AU

Orbital period628.1 days (1.72 years)
Eccentricity.2542562363769903 (0 = circular, closer to 1 = more elongated)
Semi-major axis1.43540982918248 AU
Inclination19.93757105236689° (tilt of its orbit vs. Earth's)
Perihelion distance1.070447928356004 AU (closest approach to the Sun)
Aphelion distance1.800371730008955 AU (farthest from the Sun)
Minimum Orbit Intersection Distance0.08781 AU = 13,136,398 km
(closest its orbit path ever comes to Earth's, regardless of timing)
Ascending node longitude12.50496371137005°
Argument of perihelion334.6180562368446°
Mean anomaly / motion175.8011907105248° / .5731129214315006°/day
Jupiter Tisserand invariant4.580 (helps distinguish asteroids from comets)
Reference epoch / equinoxJD 2461000.5 / J2000
Orbit determined2021-04-14 21:33:58
Observed2002-10-04 to 2002-11-07 (34 day arc, 79 observations used)
Orbit uncertainty6 (0 = best known, 9 = least certain)

Close Approach History

Every close approach NASA has on record for this object — 7 total.

an approach today (2026-10-17) — next after that: 2033-09-26

Date Passed near Velocity (km/h) Miss distance
2033-09-26 next Earth 41508.68 43,618,179 km
113 LD
2026-10-17 today Earth 69791.01 73,549,238 km
191 LD
2014-10-09 Earth 51200.74 37,307,244 km
97.1 LD
2002-10-02 Earth 40145.38 13,274,663 km
34.5 LD
1990-09-26 Earth 40579.29 39,570,547 km
103 LD
1971-10-10 Earth 52933.69 41,061,755 km
107 LD
1959-10-02 Earth 40724.83 13,463,016 km
35.0 LD

Looked up from NASA's NeoWs API and cached — last refreshed 2026-10-12T23:31:57.551781+00:00.