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Fireball Spotted over Northeastern USA

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Re: Fireball Spotted over Northeastern USA

#141

Post by VLM »

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?

Have to hold multiple concepts in head at the same time.

If you're "far away" with gravitational potential energy and get "close" to the atmosphere that potential will have to go somewhere and it'll go into speed. Its like how, without a parachute on earth, falling 40 M means about 100 KM/h impact speed. And parachutes don't work outside the atmosphere so its retrorockets or hit pretty fast. Going from up there to down here means a certain velocity on the fall in.

Conceptually there is a calculatable difference between the speed "from infinity if the earth were not orbiting the sun" vs "from entering the earth's sphere of influence where the earth gravity matters more than the sun's gravity" but it turns out not to matter much. You're probably going to be coming in very fast from falling into the sun's gravity well. But even if the stars align and you hit the earth's influence at zero m/s (LOL good luck) you'll still hit the atmosphere "around escape velocity" after some rounding.

Re: Fireball Spotted over Northeastern USA

#142

Post by nonethewiser »

andrepd wrote: post #133
mh- wrote: post #3

In case the link won't load for anyone else, there's a YouTube video on the page: https://www.youtube.com/watch?v=RfNdaYqVxR0

Why is the top suggestion on a science video like that an anti-vax rant?

I don’t think a video of a meteor is a science video. It’s simply a phenomenon.

The scientific method or institutions are helpful for understanding it but it’s not inherently scientific.

Re: Fireball Spotted over Northeastern USA

#143

Post by kerpotgh »

andrewinardeer wrote: post #101
mh- wrote: post #3

In case the link won't load for anyone else, there's a YouTube video on the page: https://www.youtube.com/watch?v=RfNdaYqVxR0

I wish I had the resources to have a HD camera pointed at the sky 24/7 and recording capacity for moments like these.

[dead]

Re: Fireball Spotted over Northeastern USA

#144

Post by pjsg »

andrewinardeer wrote: post #101
mh- wrote: post #3

In case the link won't load for anyone else, there's a YouTube video on the page: https://www.youtube.com/watch?v=RfNdaYqVxR0

I wish I had the resources to have a HD camera pointed at the sky 24/7 and recording capacity for moments like these.

Doing this is not actually that complicated -- check out https://globalmeteornetwork.org/ for more information.

I have a camera pointing due south in Massachusetts and I didn't record it -- I think it was too far west from my position.

This was my meteor stack for that night: http://server.istrastream.com/rms/US001N/stack/1678618383.jp... Yes, some of these tracks are planes, and there are a bunch of planes (see http://server.istrastream.com/rms/US001N/captured_stack/1678... for the unfiltered set!)

Total cost is certainly under $150 for the camera, housing etc. The bigger challenge is finding a good place to install the camera that has a good view of the sky.

Re: Fireball Spotted over Northeastern USA

#145

Post by jaywalk »

School-Cotton wrote: post #131
askonomm wrote: post #120

Earlier quoted context omitted.

For a moment I thought you are an Estonian, because we, too, call it a falling star. But our military service is still mandatory :(

We call it a falling star in English too (though “shooting star” is more common, at least in my experience).

I have never heard the term "falling star" before this thread.

Re: Fireball Spotted over Northeastern USA

#146

Post by rout39574 »

nerpderp82 wrote: post #76
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.

Not a hallucination.

Black body radiation coming off that thing that's nearly sun-hot pumps a lot of energy out into the world. Everything that can absorb some of it does so, and twitches.

We tend to think of radio receivers as something special, but they're highly optimized versions of processes going on all the time all around us.

The clearest example I've personally experienced of this was out in the boonies watching a meteor shower with an astronomy club. After a few times hearing my glasses "hiss" just as I was seeing a meteor I asked about it and the fellow in charge (chair of the college astro department) filled us in. It was freakin' awesome.

Re: Fireball Spotted over Northeastern USA

#147

Post by ornornor »

rob74 wrote: post #129
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…

The "relatively slow" 11 km/sec is still 39.600 km/h, or around Mach 30 (although that depends on air density and temperature), so still pretty fast I would say...

The scale of things in astronomy is humbling to say the least. "Close" can be 1 light-year away... That's 9.4607e+12 km. "Slow" is Mach 30. We're nothing at that scale.

Re: Fireball Spotted over Northeastern USA

#148

Post by Shared404 »

jaywalk wrote: post #145
School-Cotton wrote: post #131

Earlier quoted context omitted.

We call it a falling star in English too (though “shooting star” is more common, at least in my experience).

I have never heard the term "falling star" before this thread.

Can second having heard "falling star" in English as well, though "shooting star" is more common.

Maybe a result of regional dialect/language exchange in high immigration areas?

Re: Fireball Spotted over Northeastern USA

#150

Post by eternalban »

VLM wrote: post #138
eternalban wrote: post #80

Earlier quoted context omitted.

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?

You all in the comments are rediscovering Lagrange points the hard way. L4 and L5 are stable, BTW, and we have a relatively famous space telescope at L2 which requires active stability control to stay there. https://en.wikipedia.org/wiki/Lagrange_point

Thanks. I wonder if something similar is responsible for the gaps in atomic orbitals.

https://upload.wikimedia.org/wikipedia/commons/d/d0/Lagrangi...

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