Having a celebrity drop in to help commemorate an event isn’t unusual.
But what if that event was the Tunguska explosion that flattened 849 square miles of Siberia in 1908? And the “celebrity” is a 1.4-mile Planet Killer asteroid?
The United Nations has designated June 30 as International Asteroid Day.
That’s the date of the Tunguska Event – the largest observed strike in recorded history. The idea is to raise public awareness of the asteroid impact hazard.
But two uninvited guests are determined to help celebrate its 8th incarnation this year.
One is designated 415029 (2011 UL21). It’s the size of Mount Everest.
And this official public health hazard will be one of the closest asteroids to plunge past planet Earth this year.
The other is an unexpected arrival.
It was only discovered only a week ago.
It’s called 2024 MK. It’s 492 feet across. And it will come closer to Earth than the Moon on June 29.
Planet Killer 2011 UL21 is moving at 16.1 miles a second (75.5 times the speed of sound).
Studies of the amount of light it reflects as it spins every 2.7 hours indicate it is somewhere between .93 and 2.36 miles in diameter.
The European Space Agency (ESA) pins it down further, saying it’s about 1.4 miles across.
Asteroid 2024 MK is moving at 5.82 miles/s (27 times the speed of sound). Initial estimates judge it to be about 492 feet across.
The ESA warns the discovery of 2024 MK just days out from Earth “highlights the ongoing need to improve our ability to detect and monitor potentially hazardous near-Earth objects (NEOs)”.
The monster believed to have exterminated the dinosaurs 66 million years ago is estimated to have been some 6.2 miles wide.
In comparison, the space rock that devastated 80 million trees at Tunguska is believed to have been just 49.2 feet in diameter.
Cosmic pinball
A review was recently conducted into the orbits of all known asteroids to reassess the potential risk they posed to Earth.
“It’s good news,” University of Colorado Boulder researcher Oscar Fuentes-Muñoz told the Massachusetts Institute of Technology (MIT) Review.
“As far as we know, there’s no impact in the next 1000 years.”
Even a close encounter with asteroids the size of 2011 UL21 is considered a rare event.
One passes near enough to observe about once in a decade.
While officially classified as “mid-sized”, it’s still larger than 99 percent of all known asteroids.
And it is one of the 10 biggest asteroids observed passing within 4,350,000 miles of the Earth over the past century.
As a result, the Bellatrix Astronomical Observatory in Ceccano, Italy, will be watching closely as 2011 UL21 passes its closest point shortly before dawn Friday Australian time.
It will livestream the visual feed via The Virtual Telescope Project.