It seems humanity can breathe a slight sigh of relief for now, as NASA has reduced the chance of a ‘city-killer’ asteroid colliding with Earth.
Asteroid 2024 YR4 – which was only discovered back in December – now has a 1-in-67 (1.5 per cent) likelihood of hitting our planet on December 22, 2032.
This is significantly down from the space agency’s earlier prediction of one-in-32 (3.1 per cent) made earlier this week.
In a post on X (Twitter), NASA shared new ground-based telescope observations of the rock, which is estimated be about 130 to 300 feet (40 to 90 metres) across.
NASA said in the tweet: ‘New observations of asteroid 2024 YR4 helped us update its chance of impact in 2032.
‘The current probability is 1.5%. Our understanding of the asteroid’s path improves with every observation.’
However, by April 2025, the object will be so far away that it will become too faint to be detected by Earth-based telescopes.
Further updates will not be possible until 2028 when 2024 YR4 approaches Earth and becomes bright enough to be detected again.
In a post on X (Twitter), NASA posted new observations of the space rock, which is estimated be about 130 to 300 feet (40 to 90 metres) across
A scary simulation video was created to show what would happen if the asteroid hit New York City, revealing the impact would level buildings
NASA’s planetary defence department is constantly tracking the object’s trajectory, and provided the update in a blog post.
On Tuesday, it updated the impact probability of asteroid 2024 YR4 in 2032 to 3.1 per cent – the highest impact probability NASA has ever recorded for an object of this size or larger.
However, on Wednesday, new data collected overnight has reduced the impact probability to a 1-in-67 (1.5 per cent) chance.
Asteroid 2024 YR4 orbits the sun on an elliptical orbit – meaning one that its elongated and not perfectly circular.
Right now, it is actually relatively close to Earth – around 30 million miles away – which is why NASA telescopes can detect it in the night sky.
It is moving further away because it’s set to begin an orbit around the sun – but by December 2032 it’s due to come concerningly close to, or even hit, our planet.
If and when it impacts Earth, the asteroid will be travelling an astonishing 85 million miles per hour (38,000 km per second) approximately.
Asteroids speed up as they approach the sun because of the increased gravitational pull from the sun as they get closer.
This image shows the orbit of asteroid 2024 YR4 in purple with the sun in the centre and orbits of planets (Mercury = cyan; Venus = yellow; Earth = dark blue; Mars = red). Note the asteroid’s position (purple dot) in relation to Earth (dark blue dot) about a month before an impact might happen
NASA says: ‘For 2024 YR4, we are still in the information gathering stage. The likelihood of an Earth impact is still very low and will likely decrease as we gain more observations’. Pictured, artist’s impression of an Earth-bound asteroid
If this space rock were to hit Earth, it would create a blast equivalent to detonating 7.7 megatons of TNT and leave a 3,000-foot-wide crater in the ground.
The shockwave radiating out from the impact would wipe out an area the size of a major city – which is why it has been designated a ‘city-killer’.
Retired Canadian astronaut Chris Hadfield has compared asteroid 2024 YR4 to ‘a bullet zeroing in on Earth from deep space’.
‘It’s about 500 times more powerful than the biggest bomb we exploded during World War II,’ he told LBC News.
According to current calculations, the ‘risk corridor’ where it could potentially hit stretches from northern South America across the Pacific to sub-Saharan Africa and into Asia.
Worryingly, this path extends over several densely populated regions including Chennai, India and Hainan Island, China.
In May, the James Webb Space Telescope (JWST), the most powerful telescope ever built, is scheduled to observe this asteroid.
The data it gathers should help astronomers significantly narrow down where it might hit Earth in 2032.
The current ‘risk corridor,’ or the geographical area where the 2024 YR4 is most likely to hit, runs from South America across the Atlantic Ocean to sub-Saharan Africa
2024 YR4 (pictured) is already so far from Earth that most telescopes can’t see it and will disappear beyond sight in April. Astronomers must gather as much data about the asteroid as possible before then in order to plan for when it returns in 2028
Alternatively, instead of slamming into Earth’s surface, 2024 YR4 may enter Earth’s atmosphere but explode in mid air in what’s known as an ‘airburst,’ like Tunguska asteroid in 1908.
Asteroid 2024 YR4 is thought to be at least the same size as the Tunguska asteroid, which had an estimated diameter of 130 feet, according to NASA.
The agency says: ‘The exact size of 2024 YR4 is still uncertain, but an airburst is a likely scenario for its size range.’
If we imagine that the asteroid is definitely on course for Earth, humanity’s best chance may be deflecting it off course by intentionally hitting it with a spacecraft.
NASA demonstrated that this form of sophisticated planetary defence technique is indeed possible back in 2022, when its DART craft hit the asteroid Dimorphos.
Although DART ‘worked wonders’, Dr Robin George Andrews, a volcanologist and author in London, said we ‘might not be able to stop 2024 YR4’ in a similar way.
‘It doesn’t mean we can use kinetic impactors like it to deflect any asteroid whenever we want,’ Dr Andrews said.
Of course, it’s overwhelmingly likely that the asteroid will pass by Earth on December 22, 2032 – leaving our planet unscathed.
Asteroid 2024 YR4 is about the same size as the Tunguska asteroid, which caused the largest impact event in recorded history when it shot through Earth’s atmosphere in 1908, flattening 830 square miles (2,150 square km) of forest (pictured)
The Dimorphos space rock is pictured here as seen by the DART spacecraft 11 seconds before impact. Dimorphos did not pose any danger to Earth; instead, DART was rehearsal of what may be required if a space rock does one day threaten our planet
Dr Andrews thinks the odds will plummet to zero ‘as the orbit of the asteroid is more precisely defined’.
Going forward, the odds of the asteroid hitting Earth will keep changing repeatedly as the rock hurtles along its looped trajectory.
The constantly-shifting odds are due to the rock’s multi-million mph movement through space, which is made more difficult to discern when the full moon is out and there’s more moonlight.
‘We can expect the probability numbers to wobble around a bit,’ said Professor Richard Binzel, astronomer at Massachusetts Institute of Technology (MIT).
‘This is simply how scientific data measurements play out.’
