Some asteroids can “sneak” at us thanks to the skew of Earth’s rotation that makes it look like they’re barely moving – making them hard to detect.
That’s the warning of NASA-funded experts who investigated how telescopes roughly reported a 328-foot-wide asteroid that came 43,500 miles from Earth in 2019.
The space rock, dubbed ‘2019 OK’, was the first object of this size to come close to our planet since 1908 – but was spotted just 24 hours before its closest approach.
The team decided it was because it was moving toward us in such a way that its motion across the night sky would interfere with the Earth’s rotation.
And so — for early warning systems like Pan-STARRS1 at the Haleakala Observatory in Hawaii — 2019 looked a solid well, so the automated detection software wasn’t triggered.
In fact, experts said, as many as half of the asteroids that approach Earth from the eastern “opposition” danger zone are likely to experience periods of apparent slow motion.
An asteroid is said to be in opposition when placed in the night sky placing it along a line that intersects both the Earth and the Sun.
This means that half of these asteroids may be difficult to detect at the moment – and computerized telescopes will need to be updated to account for the effect.
Some asteroids can sneak up on us thanks to the skew of Earth’s rotation that makes it look like they’re barely moving – making them hard to spot (stored image)
Pictured: Some asteroids approaching Earth from east of the encounter (yellow line) appear at the exact same point in the sky as you approach. This is because when the asteroid appears to be moving east across the night sky, that motion is negated by the Earth’s rotation – meaning it’s seen from the exact same angle from Earth even as it approaches (represented by a series of parallel, dashed orange lines)
What if… 2019 OK Does it hit the ground?
Although not large enough to cause a global catastrophe, 2019 would have been quite devastating had it impacted the Earth – especially in a densely populated environment.
“It’s a killer asteroid for the city,” Swinburne University astronomer Alan Duffy told the Guardian. Sydney Morning Herald.
“It would have hit with more than 30 times the energy of the atomic explosion in Hiroshima.”
The study was conducted by astronomer Richard Winscott of the University of Hawaii at Manoa and colleagues.
“NEOs approaching from the direction east of the opposition – most notably from 0 to 2 hours [0–30°] Eastern Opposition – Prone to periods of slow motion during their approach, the researchers explain in their paper.
The induced surface-centric motion caused by the Earth’s rotation cancels out the normal eastward motion in the sky, causing the object to appear nearly stationary, making detection difficult.
“Reconnaissance should take extra care when scanning the sky in this direction, and vigorously pursue new, slow-moving objects.”
Had the apparent slow-motion phenomenon not been at play with asteroid 2019 well, the researchers said, the NEO would likely have been detected up to four weeks before it made its closest approach to our planet.
As NASA defines it, a near-Earth object – or “NEO” – is any object that lies within 28 million miles (45 million kilometers) of the Earth’s orbital path around the sun.
Any near-Earth object whose orbit exceeds that of our planet and is more than 460 feet (140 meters) in diameter is classified as a “Potentially Hazardous Object” (PHO).
In 1994, the US Congress mandated that NASA should classify at least 90 percent of near-Earth objects more than 0.6 miles (1 kilometer) across—that is, large enough to cause a global catastrophe if they hit Earth.
This target was achieved in 2011. However, the guidance was updated in 2005 to include indexing 90 percent of all PHOs by 2020 – a target that, so far, has not been met, the current figure being around 40 percent.
“We have a way to go,” Professor Winscott said. telegraph.
However, he added, “Once we rank above 90 percent, the number that can sneak up on us from [the danger zone] will be small.
For early warning systems like the Pan-STARRS1 at the Haleakala Observatory in Hawaii, 2019 OK — seen here at four different times on July 7, 2019, before being flagged — looked static, so the automated detection software wasn’t triggered
The dangers of devastating collisions were recently highlighted in the Netflix movie ‘Don’t Look Up’, in which Leonardo DiCaprio and Jennifer Lawrence star as two scientists trying to warn an unconcerned audience of a culprit on their way to eradicating humanity.
In case you’re worried about Armageddon’s demise, Professor Winscott said people “shouldn’t lose sleep” because of the possibility.
But he added: ‘In case we find something that’s going to hit the ground, we’d like to do something about it!
“It’s not about finding them and sitting there and letting them beat up.”
In fact, NASA is currently on a mission to explore the feasibility of diverting an asteroid by colliding with a space probe.
The DART ‘Double Asteroid Redirection Test’ mission launched from Vandenberg Space Force Base in California last November, and is expected to reach its target – the small moon Demorphos – in late September this year.
The full results of the study were published in the journal Icarus.
Explanation: The difference between an asteroid, a meteorite, and other space rocks
that asteroid A large piece of rock left over from collisions or the early solar system. Most of them are located between Mars and Jupiter in the main belt.
a comet It is a rock covered with ice, methane, and other compounds. Their orbits take them far from the solar system.
a meteor It is what astronomers call the flash of light in the atmosphere when debris burns.
This same wreck is known as a meteor. Most of them are so small that they flow into the atmosphere.
If any of this meteorite reaches Earth, it is called a meteor.
Meteorites, meteorites, and meteorites usually originate from asteroids and comets.
For example, if the Earth passes through the tail of a comet, a lot of debris burns up in the atmosphere, forming a meteor shower.
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