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Three biggest ‘potentially hazardous’ planet-killer asteroids revealed by Nasa – and one is four miles wide

NASA is spotting dangerous asteroids all the time which are classed as “potentially hazardous”.

Thankfully, they don’t pose any actual threat to us on Earth.


53319 (1999 JM8) is the biggest potentially hazardous asteroid known to exist

The term is used as a warning for large rocks which could cause devastation if they did crash into us.

For now, experts don’t expect any to come remotely near for hundreds of years, so no need to panic.

But we should be prepared for the future, something Nasa has been working on with its recent DART mission which deflected an asteroid by smashing a spacecraft at it.

There are actually more than 30,000 near-Earth asteroids in the solar system.

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Some are even hiding in the glare of the Sun.

Here are some of the biggest we know to exist.

Though the measurements are always approximate of course.

It’s quite hard to tell the real size of an asteroid as the measurements are based on things like brightness and reflections.

3122 Florence (1981 ET3)

3122 Florence (1981 ET3) was discovered way back in Marsh 1981.

It’s estimated to have a diameter of about three miles.

In 2017, the rock made a close approach to Earth, getting about eighteen times the average distance of the Moon.

3200 Phaethon (1983 TB)

3200 Phaethon (1983 TB) was first seen in October 1983.

The asteroid’s diameter is approximately 3.8miles long.

It made a close encounter in 2017 but won’t make another like it again until 2093.

53319 (1999 JM8)

53319 (1999 JM8) is the biggest potentially hazardous asteroid known to exist at 4.3miles.

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It was found much later than other big rocks, in 1999.

Fortunately, its next close approach isn’t expected to happen until 2075.

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