This week, two asteroids – one big enough to destroy a city and another so big it could end civilization – are expected to fly near our planet.
Don’t panic.
Both have a zero percent chance to impact the Earth. And depending on where you are in the world, you might even be able to see one.
The larger of the pair, (415029) 2011 UL21, will travel to a distance more than 17 times farther than the Moon on Thursday at 4:14 p.m. Eastern Time. It is 7,600 feet long, but it will be too far away to easily spot without a powerful telescope.
However, two days later, the smallest space rock, named 2024 MK, will come significantly closer to humanity. On Saturday, at 9:46 a.m. Eastern Time, it will pass close to Earth at 75% of the Moon’s distance. If you have a decent backyard telescope or maybe even with some good binocularsand your sky is cloudless, you might see the 400- to 850-foot rock as a point of light crossing the starry sky before sunrise.
“The object will be moving quickly, so you need to have some skills to spot it,” said Juan Luis Canomember of the Planetary Defense Office of the European Space Agency.
Stargazers in the United States, particularly those further southwest, might spot the asteroid flying overhead. Those at the top of Hawaii’s Mauna Kea volcano will be in a good position to see it when the asteroid passes before sunrise. However, it may be people in South America who have the easiest viewing experience, said Andrew Rivkinplanetary astronomer at the Johns Hopkins University Applied Physics Laboratory.
Small asteroids And cometary fragments Sometimes pierce the Earth’s atmosphere, creating a harmless light show. Many other rocky and icy shards narrowly miss the planet and often slip between Earth and the Moon.
An asteroid the size of 2024 MK threading this celestial needle is less common. “Events this close are rare but occur on decadal timescales – this will be the third (to our knowledge) this century,” Dr. Rivkin said in an email.
Anyone who fails to spot 2024 MK shouldn’t feel left out for too long. On April 13, 2029, Apophisan asteroid, 1,100 feet long, will fly less than 20,000 miles above Earth’s surface, closer than the orbits of geosynchronous satellites, meaning it will be visible to the naked eye.
Such close-up approaches are useful to planetary defense researchers. This week’s asteroids will be pinged by radar networks on Earth, allowing their dimensions and progress to be accurately determined.
“These measurements will significantly reduce the uncertainties in their movement and allow us to calculate their longer-term trajectories,” said Lance Bennerprincipal investigator of the Asteroid Radar Research Program at NASA’s Jet Propulsion Laboratory.
The double hover also serves as a chance glimpse of Asteroid Day on June 30 – a United Nations-sanctioned event designed to raise awareness of asteroid impacts.
On that day in 1908, A space rock about 160 feet in diameter exploded over a remote part of Siberia, instantly leveling 800 square miles of forest, or about the size of the Washington DC metropolitan area. It is known as the Tunguska Event, named after a river flowing through the region that it destroyed.
Although more are discovered every year, most near-Earth asteroids capable of destroying a city are yet to be found. Fortunately, many more could be spotted thanks to a pair of telescopes under construction – the Multipurpose Telescope Vera C. Rubin Observatory in Chile and at NASA Near-Earth Object Surveyor Spacecraft.
Asteroid 2024 MK is at least twice as long as the Tunguska impactor. It is certainly encouraging that the asteroid was discovered before its encounter with Earth and that we miss it. But astronomers just discovered the space rock on June 16.
“The 2024 MK case is another reminder that there are still many large objects to be found,” Dr. Cano said. Space agencies have the plans and technology to defend the planet killer asteroids – but only if they find them before the asteroids find us.
