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Fireball Spotted over Northeastern USA

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Re: Fireball Spotted over Northeastern USA

#71

Post by cik2e »

vba616 wrote: post #57
FPGAhacker wrote: post #31

Earlier quoted context omitted.

Do meteors ever hit the atmosphere at low speed?

Yes, relatively speaking. First likely hit I found: "Meteors enter the atmosphere at speeds ranging from 11 km/sec...to 72 km/sec ... The wide range in meteoroid speeds is caused partly by the fact that the Earth itself is traveling at about 30 km/sec (67,000 mph) as it revolves around the sun. On the evening side, or trailing edge of the Earth, meteoroids must catch up to the earth’s atmosphere to cause a meteor, an…

So this can't be a meteor then. That's not 11 km/s unless the video has been drastically slowed down.

Re: Fireball Spotted over Northeastern USA

#72

Post by vikingerik »

anamexis wrote: post #55
jacquesm wrote: post #38

Earlier quoted context omitted.

11.2 km/sec at a minimum. (Earth's escape velocity!)

It's not immediately obvious to me – why would escape velocity also be the minimum speed at which an object could enter the atmosphere?

It's not the minimum possible, but it is the minimum typical case.

Escape velocity is the upwards velocity needed at the surface to reach an unbounded height with velocity zero. Run that in the other direction and you see an object that starts from infinity will reach Earth at escape velocity.

For that not to happen, you'd need something to perturb the object, slowing its fall or deflecting its velocity in some direction other than down. This can happen from the Moon, but it's not common given its small mass and gravitational field relative to Earth.

Re: Fireball Spotted over Northeastern USA

#73

Post by 13of40 »

cik2e wrote: post #71
vba616 wrote: post #57

Earlier quoted context omitted.

Yes, relatively speaking. First likely hit I found: "Meteors enter the atmosphere at speeds ranging from 11 km/sec...to 72 km/sec ... The wide range in meteoroid speeds is caused partly by the fact that the Earth itself is traveling at about 30 km/sec (67,000 mph) as it revolves around the sun. On the evening side, or trailing edge of the Earth, meteoroids must catch up to the earth’s atmosphere to cause a meteor, an…

So this can't be a meteor then. That's not 11 km/s unless the video has been drastically slowed down.

I'm sure you've seen a plane traveling 400 mph but seemingly hovering in one spot in the sky. It's just not moving perpendicular to your vision.

Re: Fireball Spotted over Northeastern USA

#74

Post by buck4roo »

AYBABTME wrote: post #69
vba616 wrote: post #57

Earlier quoted context omitted.

Yes, relatively speaking. First likely hit I found: "Meteors enter the atmosphere at speeds ranging from 11 km/sec...to 72 km/sec ... The wide range in meteoroid speeds is caused partly by the fact that the Earth itself is traveling at about 30 km/sec (67,000 mph) as it revolves around the sun. On the evening side, or trailing edge of the Earth, meteoroids must catch up to the earth’s atmosphere to cause a meteor, an…

I wonder, if a meteor was moving very slowly (relatively) and basically just gently falling to earth, if we'd notice.

Yes. They are the largest source of extraterrestrial mass. https://www.sciencealert.com/5-200-tons-of-micrometeorites-a...

Re: Fireball Spotted over Northeastern USA

#76

Post by nerpderp82 »

andrewstuart wrote: post #68

I saw a meteor once when I was a kid. I was on the beach and it streaked across the sky and exploded into a bunch of other things that streaked a little further and faded out. I never really told anyone because it seem so preposterous that I wasn't really sure I had seen it at all. It was well out over the over the ocean a number of kilometeres and up very high - zero chance it was fireworks and there weren't ny on t…

I saw something similar, the weird thing is my brain hallucinated sound that couldn't have possibly been there. It was on dark winter night during a ferry crossing and the chunks intersected the horizon.

Re: Fireball Spotted over Northeastern USA

#78

Post by vba616 »

cik2e wrote: post #71
vba616 wrote: post #57

Earlier quoted context omitted.

Yes, relatively speaking. First likely hit I found: "Meteors enter the atmosphere at speeds ranging from 11 km/sec...to 72 km/sec ... The wide range in meteoroid speeds is caused partly by the fact that the Earth itself is traveling at about 30 km/sec (67,000 mph) as it revolves around the sun. On the evening side, or trailing edge of the Earth, meteoroids must catch up to the earth’s atmosphere to cause a meteor, an…

So this can't be a meteor then. That's not 11 km/s unless the video has been drastically slowed down.

I just read a page on meteors that said they tend to blow up starting around 300,000 to 200,000 feet or so.

If I make a wild-ass guess that the fireball was visible over a trajectory of about 100,000 feet, that's about 30 km.

At 11 km/s, then, it should appear for around 3 seconds.

I rewatched the video, which is 5 seconds in all, and it looks to me like the light is pretty close to three seconds long.

Aside from that, sure, it could've been slowed down, and could be at an angle, so it may all be a coincidence.

Re: Fireball Spotted over Northeastern USA

#80

Post by eternalban »

roywiggins wrote: post #66
IIAOPSW wrote: post #60

Earlier quoted context omitted.

You haven't accounted for the massive gravity well that is the sun. The difference in potential energy from infinity to the radius of Earths orbit is GMm/r. Set that equal to momentum (.5mv^2) and you get sqrt(2GM/r). Plug in the numbers and you'll see you can't really have a meteor that stumbled in from outside the solar system with a similar velocity to Earths orbit by the time it came down to Earths orbit. Put ano…

Near-earth asteroids periodically wander into temporary orbits around the Earth and then wander off. https://earthsky.org/space/2020-so-mini-moon-asteroid-or-spa...

Thanks for the link.

"Strange space object 2020 SO was discovered on September 17, 2020, on approach to Earth. On November 8, it slowly drifted into Earth’s sphere of gravitational dominance, to become a new mini-moon. It’ll escape back into a new orbit around the sun in March 2021. During that time, it’ll make 2 large loops around our planet."

Why would it leave orbit if it already does 2 circles?

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