2022_UR4

<span class="nowrap">2022 UR<sub>4</sub></span>

2022 UR4

Small near-Earth asteroid

2022 UR4 is a small near-Earth asteroid that made an extremely close approach within 0.044 lunar distances (17,000 km; 11,000 mi) from Earth's center on 20 October 2022 at 22:45 UTC.[4] It was discovered about 14 hours before closest approach by the Asteroid Terrestrial-impact Last Alert System (ATLAS) survey telescope at Mauna Loa Observatory, Hawaii on 20 November 2022.[2] During the close approach, the asteroid passed above the northern hemisphere of Earth and reached a peak brightness of magnitude 10,[2] just 40 times fainter than the threshold of naked eye visibility.[lower-alpha 1]

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Notes

  1. The faintest magnitude that can be seen with the naked eye is about 6.[6] Using the formula Δm = −2.5 log10(F1/F2),[6] where Δm = m1 – m2 = 6 – 10 = –4 is the magnitude difference between the naked eye limit and 2022 UR4's peak brightness, the brightness ratio F1/F2 of the naked eye limit to the peak brightness of 2022 UR4 is approximately 39.81 ≈ F1/F2 = 10(Δm/–2.5).

References

  1. [1]
    "2022 UR4". Minor Planet Center. Retrieved 30 November 2022.
  2. [2]
    "MPEC 2022-U145 : 2022 UR4". Minor Planet Electronic Circular. Minor Planet Center. 21 October 2022. Retrieved 30 November 2022.
  3. [3]
    "2022 UR4". NEO Exchange. Las Cumbres Observatory. 20 October 2022. Retrieved 30 November 2022.
  4. [4]
    "JPL Small-Body Database Browser: (2022 UR4)" (2022-10-20 last obs.). Jet Propulsion Laboratory. Retrieved 30 November 2022.
  5. [5]
    "Asteroid Size Estimator". Center for Near Earth Object Studies. NASA. Retrieved 30 November 2022.
  6. [6]
    Mihos, Chris (2005). "The Magnitude Scale". Case Western Reserve University. Retrieved 30 November 2022.
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