Large asteroid flies close to Earth - and is only spotted by astronomers a few days later

An asteroid the size of a skyscraper narrowly passed the Earth, and was not spotted by astronomers until two days later.

NASA said the object, named 2023NT1, was spotted by the Asteroid Terrestrial-impact Last Alert System (ATLAS), an array of telescopes designed to spot asteroids several days to weeks before any potential impact with Earth, in South Africa, and was up to 60 meters in size.

It was travelling at an estimated 86,000 km/h speed and entered a 60,000-mile radius of the planet – which is about 1/4 the moon's distance to Earth.

The asteroid was spotted on 15 July, two days after its close approach. Scientists say 2023NT1 was hard to see as it approached Earth in the direction of the sun, which blinded telescopes.

After calculating the asteroid's trajectory for the next decade astronomers say asteroid 2023 NT1 doesn't pose any danger to Earth.

However, an asteroid that big could have caused significant damage. The Chelyabinsk meteoroid from 2013 was only 20 metres wide and injured 1,500 people and damaged buildings when it burst through our atmosphere.

The European Space Agency estimates there could be a million asteroids in the same size range of 30 to 100 metres near Earth. And 98.9% of them are still undiscovered.

The space agency says there needs to be an improvement in the capabilities of humanity to detect such asteroids. Some are already being worked on, such as ESA’s NEOMIR, which will orbit between the Sun and the Earth and is designed to work as an early warning system for asteroids that may otherwise avoid detection, but that will not launch until 2030.