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Astronomers spot closest Earth-buzzing asteroid ever recorded :
Astronomers have identified an asteroid that's just made the closest pass to Earth ever recorded – and it was only spotted after it had passed. The object skimmed Earth's atmosphere over the weekend, close enough to have its orbit changed by the planet's gravity.
On August 16, an asteroid designated 2020 QG whizzed past our planet at a distance of only 2,950 km (1,830 mi) above the surface. That's well within the altitude of many satellites, and almost twice as close as the previous record-holder, an asteroid called 2011 CQ1. Of course, this record is about the closest pass to Earth, and doesn't include objects that have impacted the planet.
That said, even if it had hit, asteroid 2020 QG wouldn't have caused any damage. It measures about 3 to 6 m (10 to 20 ft) wide, meaning it would have just burned up in the atmosphere.
Perhaps the Monolith was doing a fly-by.
(Score: 3, Interesting) by Immerman on Friday August 21 2020, @02:32PM (2 children)
Lighting is typically measured relative to the observer. Without an atmosphere to scatter light, something that is backlit is functionally unlit, and invisible against the black background of space.
But yeah, off-world observation posts are definitely a necessity to detect such things. I believe I've heard some proposals for observatories at the L4 and L5 points for exactly that reason - they'd be far enough away to be able to see things that are backlit from Earth's perspective.
Another option that can be closer to home is thermal infrared observatories - those still have to be in orbit since the atmosphere scatters infrared, but they can remain close to Earth since they're looking for an object's thermal glow and thus don't depend on the direction of lighting from the sun.
(Score: 1) by khallow on Saturday August 22 2020, @12:33AM (1 child)
And as I noted the observer can be in different places, so that the vagaries of trajectory can be accounted for.
Several of the Sun-Earth Lagrange points would be useful - L1, L4, and L5. L1 in particular is about 1.5 million km out directly towards the Sun. Anything approaching Earth from the Sun-ward side has to pass it. Even fast objects that are barely in solar orbit would take the better part of a day to reach Earth, if they were spotted 1.5 million km out.
(Score: 2) by Immerman on Saturday August 22 2020, @02:24AM
> observer can be in different places, so that the vagaries of trajectory can be accounted for.
They can in theory - but not today.
L1's not so hot as a spotting point, primarily because 14 hours isn't really enough warning to *do* anything. Get the word out to militaries so there's no nuclear "counter"-strikes, but you can't evacuate a city in that kind of time, it'll just be gridlock and rioting. Even a few days would be really pushing it. Ideally you want weeks, months if you're planning to destroy or deflect it. L4 and L5 give you that - you don't need full front-lighting to spot the things, a well-lit crescent as seen from the side will do the job just fine. And from the side you can see it coming almost as soon as it clears the sun - 100x further away than L1.