Airplane-sized asteroid found 2 days after brush by Earth

Asteroid hidden by sun’s glare

On July 15, 2023, the ATLAS observatory in South Africa discovered an asteroid up to 200 feet (60 m) in size two days after it passed closest to Earth. Astronomers designated the asteroid 2023 NT1. And NASA called it airplane-sized. Compare 2023 NT1 to the asteroid that hit Arizona some 50,000 years ago, leaving the large, famous Barringer Crater, aka Meteor Crater. The asteroid that made Meteor Crater might have been only slightly smaller (about 160 feet or 50 m in size). The newly discovered asteroid passed within only one-quarter the moon’s distance. It came closest to Earth at 10:12 UTC on July 13, 2023.

It missed us. It wasn’t a threat to Earth. But why didn’t one of our observatories pick it up sooner? The reason is the asteroid came at us from the direction of the sun, a known weak spot in our defense against space rocks.

But the European Space Agency (ESA) has a plan to shore up that weak spot.

A plan to detect asteroids by the sun

ESA has a planned mission called NEOMIR that will detect asteroids coming from the sun’s direction. The NEOMIR mission will orbit between Earth and the sun at the first Lagrange point (L1). It’ll act as an early warning system for asteroids – 65 feet (20 m) and larger – that instruments on Earth’s surface cannot see. The downside is that the launch of NEOMIR is not until 2030.

Another notable asteroid that headed toward Earth from the sun’s direction was the Chelyabinsk meteor. This asteroid broke up in the atmosphere on February 15, 2013, over Russia. Scientists estimate it was 65 feet (20 m) in size. It exploded in the atmosphere and created a shockwave that damaged thousands of buildings, breaking windows and injuring roughly 1,500 people from flying shards of glass. Moreover, it was the largest asteroid to strike Earth in over a century.

Earth in the cosmic shooting gallery

Asteroids passing close to Earth are nothing new. Fortunately, most of those asteroids are quite small or pass many times the moon’s distance from Earth, or both.

Just last month, house-sized and bus-sized asteroids passed inside the moon’s orbit just one day apart. Within the past year, some small asteroids have dropped bits of meteorites onto Earth. One little (3 m) space rock sprayed meteorites over France in February. Another dropped meteorites in Canada in November 2022.

Diagram with Earth in the middle and oblique oval for moon's orbit plus straight green arrow for path of asteroid.
View larger. | Asteroid 2023 NT1 flew 1/4 the moon’s distance past Earth on July 13, 2023. Earth is at the center of this diagram, with the oval representing the moon’s orbit and the green arrow the path of 2023 NT1. Scientists didn’t discover the asteroid until July 15, 2023, because it approached Earth from the direction of the sun. Image via IAU.

Bottom line: An airplane-sized asteroid came within 1/4 the moon’s distance to Earth on July 13, 2023. However, scientists didn’t detect the asteroid until two days after its closest approach.

Via IAU Minor Planet Center

July 16, 2023

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Kelly Kizer Whitt

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