When does 2004 OB pass Earth?
2004 OB: closest approach September 2028
2004 OB passes Earth on September 30, 2028 at 14:22 UTC, 2,242,644 km from Earth's centre (5.8 lunar distances).
Distance through the flyby
lunar distances, ±12 h (JPL Horizons)Can you see it?
JPL Horizons gives a brightest apparent magnitude of 13.1 as seen from Earth's centre, at 02:23 UTC on Sep 30, 2028: faint: only for large telescopes. At closest approach it is overhead at about 83°S, 4°E, where the Sun is up or in twilight. Seen from the ground, its position and brightness differ from the geocentric values, the more so the closer it comes.
Impact risk
2004 OB is not on JPL's Sentry impact-monitoring list: no possible impact has been found for it.
Physical data
| Absolute magnitude H | 18.97 |
| Orbit class | Apollo |
| Potentially hazardous asteroid (PHA) | yes |
JPL Small-Body Database: 440212 (2004 OB).
Every close approach, 1900–2200
All passes within 0.2 au (78 lunar distances) computed by JPL. Only 1 of them comes closer than the 2028 pass. The uncertainty column is JPL's 3-sigma timing uncertainty; it grows for dates far from today.
| Date | Lunar dist. | Distance | km/s | Time ± |
|---|---|---|---|---|
| Sep 4, 1917 | 70.4 | 27.07 million km | 13.1 | 00:02 |
| Oct 21, 1930 | 18.8 | 7.24 million km | 6.6 | 01:05 |
| Sep 29, 1967 | 4.4 | 1.67 million km | 7.5 | < 00:01 |
| Nov 22, 2004 | 21.1 | 8.12 million km | 7.2 | < 00:01 |
| Sep 30, 2028 | 5.8 | 2.24 million km | 7.4 | < 00:01 |
| Dec 6, 2052 | 31.2 | 12.01 million km | 9.0 | 00:03 |
| Sep 12, 2063 | 43.4 | 16.67 million km | 11.0 | 00:02 |
| Nov 19, 2087 | 20.8 | 8.01 million km | 6.9 | 00:03 |
| Oct 22, 2122 | 18.3 | 7.04 million km | 6.6 | 00:25 |
| Nov 3, 2157 | 20.9 | 8.03 million km | 6.6 | 00:43 |
| Nov 28, 2192 | 21.3 | 8.18 million km | 7.4 | 00:21 |
Questions
Will 2004 OB hit Earth?
2004 OB is not on JPL's Sentry impact-monitoring list: no possible impact has been found for it.
How close will 2004 OB come?
2,242,644 km from Earth's centre, 2,236,273 km above the surface, on Sep 30, 2028 at 14:22 UTC (NASA JPL).
How big is 2004 OB?
430–960 m (estimated from H = 18.97).
Can I see 2004 OB?
At its brightest about magnitude 13.1 (JPL Horizons, geocentric): faint: only for large telescopes.
Sources: NASA/JPL CNEOS close-approach data, Sentry, Small-Body Database and Horizons (geocentric ephemeris). Data fetched 30 Oct 2026, 00:24 UTC; refreshed weekly. Times converted from TDB to UTC.