Nasa on alert as asteroid hurtles towards Earth at 11 miles a second

‘There are millions of asteroids in our solar system, of which 2,350 are classified as potential hazards’

‘It is in the category of a small to moderately sized asteroid, the size of a football field’

AN ASTEROID the size of a football pitch will zoom past the Earth tomorrow, skirting the planet close enough for Nasa to issue a warning.

Asteroid 2008 OS7 is classified as “potentially hazardous” and is expected to come within 1.7 million miles of Earth – about seven times further out than the Moon – at a speed of around 11 miles per second.

Although that seems far off, it is close enough in space terms for Nasa to add it to its “asteroid watch” and experts will be keeping a close eye on its approach.

The asteroid, which passes Earth every 962 days, is expected to make its closest approach at 2.41pm GMT tomorrow.

It is estimated that a strike by an asteroid of 1,500ft diameter on a built-up area would cause a crater 11 miles wide and instantly vaporise more than two million people. The impact would be the equivalent of 141 gigatons of TNT and the fireball released would kill a further 11 million.

Dr Minjae Kim, a research fellow at the University of Warwick’s physics department, said: “We don’t need to worry about it too much as this asteroid will not enter Earth’s atmosphere ... there are millions of asteroids in our solar system, of which around 2,350 are classified as potentially hazardous. One of the most intriguing aspects of the 2008 OS7 is its estimated diameter based on its luminosity and reflective properties, ranging from 725 to 1,622ft.

“This places it in the category of a small to moderately sized asteroid, roughly equivalent to the size of a football field.”

Asteroid risk and monitoring is carried out by the Center for Near Earth Object Studies at Nasa’s jet propulsion laboratory. Most asteroids and comets have orbits that do not bring them very close to Earth, and are only classed as dangerous if they come within 4.6 million miles and are larger than 460ft. The next significant approach to Earth by a potentially hazardous asteroid will be 99942 Apophis on April 14 2029.

Nasa’s Osiris-apex is currently on route to the asteroid to study the physical changes that result from its close encounter with Earth five years from now. Apophis was also predicted to get dangerously close to Earth in 2068 but experts have since revised that risk.

Five objects would have passed close to Earth between yesterday and tomorrow. Apart from 2008 OS7, the other four vary in size from 63 to 120ft diameter. The one coming closest is 2024BJ3 which is approximately the size of an airliner and will come within 533,000 miles of us tomorrow. All are too faint to be seen with the naked eye.

Nasa takes the threat of space rocks seriously and in 2022 it carried out the first asteroid deflection test, to successfully alter the orbit of the small moonlet Dimorphos. It also sent a mission to the asteroid Bennu which could hit Earth in 2182 with the force of 22 atom bombs.

Although the odds of a catastrophic strike are 1 in 2,700, Nasa was concerned enough to launch a craft to Bennu seven years ago to collect samples, in case a deflection mission is required. The samples are now being studied by global experts including the Natural History Museum in London.