Asteroid 2018 UA flew past Earth at 0.04 LD, 4th closest on record

Asteroid 2018 UA flew past Earth at 0.04 LD, 4th closest on record

A newly discovered asteroid designated 2018 UA flew past Earth at a very close distance of about 0.04 LD / 9.14e-5 AU (15 360 km / 9 544 miles) above Earth's surface. This is the closest known asteroid to flyby Earth since the start of the year and 4th closest on record. Interestingly, this object was discovered about 90 minutes before its close approach. At best, it would produce a nice fireball and small meteoroids.

This object belongs to the Apollo group of asteroids. Its estimated diameter is between 2.5 and 5.5 m (8 and 18 feet).

2018 UA, previously known as ZU1CE58, was first observed at Catalina Sky Survey on October 19, about 90 minutes before its closest approach at 14:46 UTC today.

The object flew past us at a speed (relative to the Earth) of 14.14 km/s.

This is the 3rd known asteroid to flyby Earth within 1 lunar distance since October 7 and 56th this year.

2018 AU made history with 4th closest flyby of any known asteroid on record.

The closest known asteroid flyby took place at 19:39 UTC on February 4, 2011 (2011 CQ1) at 0.03 LD / 7.92e-5 AU, followed by 2008 TS26 at 03:30 UTC on October 9, 2008 (2008 TS26) at 0.03 LD / 8.44e-5 AU, and 2004 FU162 at 15:35 UTC on March 31, 2004 at 0.03 LD / 8.63e-5 AU.

It is also the second largest known asteroid to fly by within 0.04 LD on record.

Note: 2018 data valid 16:30 UTC, October 19. Another close flyby was reported at 17:00 UTC: 2018 UL (0.57 LD / 0.00148; size 4.1 - 9.1 m / 13.4 - 30 feet).


Asteroid 2018 UA at Minor Planet Center; at CNEOS

Featured image: ZU1CE50 flyby simulation - October 19, 2018. Credit: Tony Dunn /


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