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Discovered June 16th, large asteroid to pass between Earth and moon on Saturday

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Re: Discovered June 16th, large asteroid to pass between Earth and moon on Saturday

#11

Post by johnnyanmac »

jfengel wrote: post #5

How large? "anywhere from 120 metres to 260 metres in diameter". Is that bad? According to NASA, "If a rocky meteoroid larger than 25 meters but smaller than one kilometer ( a little more than 1/2 mile) were to hit Earth, it would likely cause local damage to the impact area. We believe anything larger than one to two kilometers (one kilometer is a little more than one-half mile) could have worldwide effects." So...…

well the Chicxulub impactor (The one that ended the Cretaceous Period) was estimated to be 10-15km. on the other end, the largest recorded asteroid in Siberia was 50-60m in size and did local but very noticeable damage[1], apparently 4x as powerful as the nuclear bomb that hit Hiroshima.

So 260m would be absolutely devastating, but wouldn't end civilization as we know it. it would absolutely destroy any state or smaller country it hit. if it hit/exploded above an ocean, we'd have record breaking tsunamis completely flood whatever coastal areas it hit.

1: https://www.euronews.com/culture/2023/06/30/culture-re-view-...

Re: Discovered June 16th, large asteroid to pass between Earth and moon on Saturday

#12

Post by dylan604 »

burnte wrote: post #3
metadat wrote: post #2

Was funding for the Asteroid Watch program drastically reduced, or why did the detection come in so late? https://www.jpl.nasa.gov/asteroid-watch

The sky is really big. No detection will ever be 100%.

Your application for a tourist visa to the Earth Planetary Visitor's Bureau has been denied due to a clerical error. Please alter your course to enter a holding orbit until your application has been resubmitted. We thank you in your interest in visiting Earth.

Re: Discovered June 16th, large asteroid to pass between Earth and moon on Saturday

#13

Post by biot »

dylan604 wrote: post #9
jfengel wrote: post #5

How large? "anywhere from 120 metres to 260 metres in diameter". Is that bad? According to NASA, "If a rocky meteoroid larger than 25 meters but smaller than one kilometer ( a little more than 1/2 mile) were to hit Earth, it would likely cause local damage to the impact area. We believe anything larger than one to two kilometers (one kilometer is a little more than one-half mile) could have worldwide effects." So...…

I'm surprised there's no TNT equivalent comparing it to the biggest weapons humans have created. That always seems like a data point used when showing destructive forces.

From the article:

> "This is a big object. An object of this size is going to have the equivalent impact energy in the hundreds of megaton approaching a gigaton," Brown said. "That'd be a regional impact. It's the sort of thing that if it hit the east coast of the U.S., you would have catastrophic effects over most of the eastern seaboard. But it's not big enough to affect the whole world."

Re: Discovered June 16th, large asteroid to pass between Earth and moon on Saturday

#14

Post by rich_sasha »

My physics might be wrong, but with Earth's radius at 6500km and Lunar orbit radius around 350,000km, probability of a collision course given asteroid being within a lunar orbit distance is only (6.5/350)^2 or 0.03%, or maybe even cleaner, 1 in 3000. So it's not that close a miss.

Re: Discovered June 16th, large asteroid to pass between Earth and moon on Saturday

#15

Post by s1artibartfast »

phkahler wrote: post #4

"Maybe the big take-home point on this one is it's a pretty big object and it was only found 10 or 12 days before closest approach," I've said this before. The way they find these things is looking for movement against the distant background / starfield. That works pretty well for finding things, but there is one problem. Any object on a collision course with earth will NOT be moving across the background in the days…

>It will appear stationary against the stars, so will not be detected by these systems. To some extent it also doesn't matter that we are orbiting the sun because while near, earth and asteroid will be in the same accelerating reference frame.

I dont think that is true aside from the case where the asteroid vector is the exact opposite of the earth.

Even if the earth and the asteroid are in the same accelerating reference plane, the background is not.

If you have two race cars going in around a track and at one from the other, it still appears to be moving relative to the stands.

Re: Discovered June 16th, large asteroid to pass between Earth and moon on Saturday

#16

Post by EA-3167 »

phkahler wrote: post #4

"Maybe the big take-home point on this one is it's a pretty big object and it was only found 10 or 12 days before closest approach," I've said this before. The way they find these things is looking for movement against the distant background / starfield. That works pretty well for finding things, but there is one problem. Any object on a collision course with earth will NOT be moving across the background in the days…

What you're describing is known as Constant Bearing, Decreasing Range (CBDR), https://en.wikipedia.org/wiki/Constant_bearing,_decreasing_r... and generally doesn't apply to to the case of a nearby asteroid on a collision course with Earth. For the parallax created by our orbit to be negligible, the object would have to be very distant.

Re: Discovered June 16th, large asteroid to pass between Earth and moon on Saturday

#17

Post by EA-3167 »

rich_sasha wrote: post #14

My physics might be wrong, but with Earth's radius at 6500km and Lunar orbit radius around 350,000km, probability of a collision course given asteroid being within a lunar orbit distance is only (6.5/350)^2 or 0.03%, or maybe even cleaner, 1 in 3000. So it's not that close a miss.

In terms of these things, its a hair's breadth, but in human terms it's incredibly distant. We don't have a great intuition about just how enormous and empty space is, how much of the universe (including our little patch) is just a seething void.

Re: Discovered June 16th, large asteroid to pass between Earth and moon on Saturday

#18

Post by jfoutz »

burnte wrote: post #3
metadat wrote: post #2

Was funding for the Asteroid Watch program drastically reduced, or why did the detection come in so late? https://www.jpl.nasa.gov/asteroid-watch

The sky is really big. No detection will ever be 100%.

For various reasons Armageddon is one of my favorite movies. Action/comedy, not exactly _good_ but I find it enjoyable.

I bring it up because of the Fictional mission commander talking to the president,

> Begging your pardon sir, but its a big ass sky.

Re: Discovered June 16th, large asteroid to pass between Earth and moon on Saturday

#19

Post by foobarian »

jfoutz wrote: post #18
burnte wrote: post #3

Earlier quoted context omitted.

The sky is really big. No detection will ever be 100%.

For various reasons Armageddon is one of my favorite movies. Action/comedy, not exactly _good_ but I find it enjoyable. I bring it up because of the Fictional mission commander talking to the president, > Begging your pardon sir, but its a big ass sky.

The best thing about Armageddon for me are open flames in vacuum.

Re: Discovered June 16th, large asteroid to pass between Earth and moon on Saturday

#20

Post by rich_sasha »

EA-3167 wrote: post #17
rich_sasha wrote: post #14

My physics might be wrong, but with Earth's radius at 6500km and Lunar orbit radius around 350,000km, probability of a collision course given asteroid being within a lunar orbit distance is only (6.5/350)^2 or 0.03%, or maybe even cleaner, 1 in 3000. So it's not that close a miss.

In terms of these things, its a hair's breadth, but in human terms it's incredibly distant. We don't have a great intuition about just how enormous and empty space is, how much of the universe (including our little patch) is just a seething void.

It's not about intuition, it's about probability of impact. All these articles talking about asteroids flying within a lunar orbit distance make it sound like we got away lucky. But that's still far, far away, and the chances of impact are quite remote, in absolute terms.
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