SkyTracko
Safe flyby

(2018 PZ21)

No riskNASA SPK-ID 3826795
Miss distance
128.9 LD

Far beyond Earth–Moon orbit

≈ 49.6 million km · 129× the Moon's distance

No impact trajectory detected.

Closest approach
Sat, Apr 18 · 00:00 UTC

11 days ago

Key metrics

Distance
128.9 LD
≈ 49.6 million km
Velocity
9.8 km/s
35314 km/h
Estimated size
12 – 27 m
🏢 ≈ a 10-story building
Approach time
Sat, Apr 18 · 00:00 UTC
11 days ago
Absolute magnitude (H)
26.7
Lower = brighter
Status
Passed
Tracked by NASA NeoWs

3D Orbital path

Size comparison

(2018 PZ21) is about 60% of 10-story building.

20 m
(2018 PZ21)
20 m
10-story building
33 m
Compare against

Hypothetical impact energy

0.1 MtTNT equivalent

Would cause significant local destruction. Comparable to a large nuclear weapon.

Hiroshima equivalents
8
Estimated mass
10.3M kg
Diameter used
20 m
Impact velocity
9.8 km/s
Assumes stony composition (2,600 kg/m³). Actual energy depends on composition, angle, and atmospheric interaction. This is NOT a prediction — this asteroid is not on a collision course.

What this means

This object passed at 129 LD — safely distant and of interest mainly to orbital surveys. No impact trajectory has been detected.

Approach timeline

18 events

Upcoming

  • Sat, Oct 17 · 10:35 UTC
    76.18 LD
    29.3 million km
    11.8 km/s
  • Thu, Jul 30 · 09:47 UTC
    54.59 LD
    21 million km
    10.4 km/s
  • Fri, Aug 9 · 04:45 UTC
    15.9 LD
    6.1 million km
    5.2 km/s
  • Sat, Oct 14 · 10:22 UTC
    20.78 LD
    8 million km
    5.6 km/s
  • Thu, Jul 29 · 08:06 UTC
    30.47 LD
    11.7 million km
    8.5 km/s
  • Fri, Aug 1 · 02:48 UTC
    9.39 LD
    3.6 million km
    5.7 km/s
  • Mon, Aug 13 · 19:57 UTC
    24.24 LD
    9.3 million km
    5.1 km/s
  • Sat, Sep 3 · 00:49 UTC
    32.1 LD
    12.3 million km
    5.1 km/s
  • Sat, Sep 26 · 07:47 UTC
    29.73 LD
    11.4 million km
    5 km/s
  • Mon, Oct 14 · 13:47 UTC
    20.67 LD
    7.9 million km
    5.9 km/s
  • Wed, Oct 18 · 07:44 UTC
    32.87 LD
    12.6 million km
    8.2 km/s
  • Sat, Oct 16 · 21:19 UTC
    64 LD
    24.6 million km
    11 km/s

Past

  • Sat, Apr 18 · 00:00 UTC
    128.93 LD
    49.6 million km
    9.8 km/s
  • Thu, Oct 6 · 06:07 UTC
    24.76 LD
    9.5 million km
    5 km/s
  • Fri, Aug 3 · 20:51 UTC
    6.83 LD
    2.6 million km
    5.7 km/s
  • Wed, Jul 30 · 02:44 UTC
    37.25 LD
    14.3 million km
    9.1 km/s
  • Fri, Oct 20 · 15:53 UTC
    43 LD
    16.5 million km
    9 km/s
  • Sun, Oct 13 · 11:43 UTC
    22.23 LD
    8.5 million km
    5.3 km/s

How we classify risk

Each object's risk class is computed locally from two NASA NeoWs signals: miss distance (in lunar distances) and estimated diameter. "Potentially hazardous" is NASA's own flag — applied when an object's orbit brings it within 0.05 AU of Earth and it's at least ~140 m across. That flag indicates monitoring interest, not an impact prediction.

No risk

Passes at a comfortable distance — routine flyby.

Watch

Close-but-comfortable. Interesting enough to highlight.

Notable

Inside 10 lunar distances — actively tracked.

Significant

Large object passing unusually close — refined each observation.

Other tracked objects

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