Thoughtful question about the sun

[YoungGun21]

So light travels at about 299,000,000m/s, obviously we know that light doesn't instantly reach us from the sun. If the sun were to just suddenly turn off (like a lightswitch) would we just not know it for a few minutes? Would our satellites pick it up before we could see it on Earth? Likewise, what would happen if the sun suddenly exploded? Would we still not know it for a few minutes?

 

[FoBoT]

yes
8 minutes

 

[ChAoTiCpInOy]

Wasn't this a Jeopardy question a couple years ago?

 

[BlackTigers]

Originally posted by: ChAoTiCpInOy
Wasn't this a Jeopardy question a couple years ago?

You mean answer?



edit....wtf happened to my smiley?

 

[Jeff7]

Originally posted by: FoBoT
yes
8 minutes

</thread>


8 minutes later

</Earth>

 

[FoBoT]

;

 

[YoungGun21]

Thats crazy. The only way to save billions of people that fast is to post it as a bulletin on myspace.

 

[theprodigalrebel]

We're supposed to evacuate Earth in under 8 minutes?

 

[frostedflakes]

Would we feel the gravity effects instantaneously or do they propagate at the speed of light as well?

 

[BlackTigers]

Originally posted by: theprodigalrebel
We're supposed to evacuate Earth in under 8 minutes?

Don't worry, it can be done.

 

[YoungGun21]

Originally posted by: theprodigalrebel
We're supposed to evacuate Earth in under 8 minutes?

Hey thats enough time for a quickie

 

[hellokeith]

Originally posted by: frostedflakes
Would we feel the gravity effects instantaneously or do they propagate at the speed of light as well?

Anandtech Highly Technical forum discussion on the speed of gravity

 

[destrekor]

Originally posted by: YoungGun21
So light travels at about 299,000,000m/s, obviously we know that light doesn't instantly reach us from the sun. If the sun were to just suddenly turn off (like a lightswitch) would we just not know it for a few minutes? Would our satellites pick it up before we could see it on Earth? Likewise, what would happen if the sun suddenly exploded? Would we still not know it for a few minutes?

no equipment will know for a few minutes (6-8, I've seen both iirc) because all light, and not just visible light, will reach nearby equipment at the same time. Relatively speaking, all the Earth-orbiting satellites are very close in terms of light speed. Maybe a few second warning from the furthest satellites?

Just like there is a star (Betelgeuse) that, iirc,is less than 500ly away... it's a red giant now and due to it's size the next stage is likely supernova. It may have went supernova 300 years ago for all we know. All telescopes in that direction still have to wait for the light to hit them.. they only magnify, not reach out across the universe.. that would be called time travel if we could instantly see the present-moment image of a far-away object, and not it's 10 billion year old image that suggests it may have died long ago... We could all be doomed? OH NOES!!! Nah, it shouldn't have an impact on our lives, but that's just an estimate. It could cause some crazy electrical storms.

 

[theprodigalrebel]

I managed to fit in a quickie (thanks Facebook bug!) since my last post. Yes, you do have a point, YoungGun21.

 

[upsciLLion]

Originally posted by: BlackTigers91

Originally posted by: ChAoTiCpInOy
Wasn't this a Jeopardy question a couple years ago?

You mean answer?

Hahaha holy shit, owned!

 

[Epic Fail]

Didn't someone post it here before?

 

[everman]

The question about light is easy, but how long would it take to detect the lack of the sun's gravitational pull? Would it be less than 8min? I guess the real question is how fast does a gravitational field move?

 

[destrekor]

Originally posted by: everman
The question about light is easy, but how long would it take to detect the lack of the sun's gravitational pull? Would it be less than 8min? I guess the real question is how fast does a gravitational field move?

if I understand correctly, gravity would not be felt until it can be visually determined to have happened, and at that same time, if close enough, the shockwave would be felt at about the same time as it's witnessed (I don't think we'll get a shockwave from our lightweight sun.
However, we won't live long enough for it to die on us. It'll burn us all first when it swells and intensifies in heat due to the increased size and closed distance between surface of sun and our orbit.

 

[DrPizza]

Originally posted by: destrekor
no equipment will know for a few minutes (6-8, I've seen both iirc) because all light, and not just visible light, will reach nearby equipment at the same time. Relatively speaking, all the Earth-orbiting satellites are very close in terms of light speed. Maybe a few second warning from the furthest satellites?

Just out of curiousity, I was wondering how you think the satellites would give us a few seconds warning. (Signals from satellites travel at the speed of light as well.) Assuming some sort of computation had to be made, even if that computation took a billionth of a second, the signal from the satellite would arrive after we saw the sun turn off.

 

[BrokenVisage]

How thoughtful of you.

 

[TechBoyJK]

this exact question was dealt with on NOVA's "the elegant universe"

 

[Epic Fail]

Originally posted by: TechBoyJK
this exact question was dealt with on NOVA's "the elegant universe"

Thanks, I think that's where I heard this question before.

 

[BoomerD]

Originally posted by: DrPizza

Originally posted by: destrekor
no equipment will know for a few minutes (6-8, I've seen both iirc) because all light, and not just visible light, will reach nearby equipment at the same time. Relatively speaking, all the Earth-orbiting satellites are very close in terms of light speed. Maybe a few second warning from the furthest satellites?

Just out of curiousity, I was wondering how you think the satellites would give us a few seconds warning. (Signals from satellites travel at the speed of light as well.) Assuming some sort of computation had to be made, even if that computation took a billionth of a second, the signal from the satellite would arrive after we saw the sun turn off.

But before someone could read the message, the lights would turn out...permanently.

 

[destrekor]

Originally posted by: DrPizza

Originally posted by: destrekor
no equipment will know for a few minutes (6-8, I've seen both iirc) because all light, and not just visible light, will reach nearby equipment at the same time. Relatively speaking, all the Earth-orbiting satellites are very close in terms of light speed. Maybe a few second warning from the furthest satellites?

Just out of curiousity, I was wondering how you think the satellites would give us a few seconds warning. (Signals from satellites travel at the speed of light as well.) Assuming some sort of computation had to be made, even if that computation took a billionth of a second, the signal from the satellite would arrive after we saw the sun turn off.

edit:
I see what you were referencing. The delay, even if near instantaneous, and no matter where the satellite was... would prevent that signal from reaching us before we witnessed the actual event. Idiot... I'm actually about go to to bed now, I blame this on lack of sleep. But yea... satellites could potentially witness the event before us, but could not report it to us any faster than the light from the actual event.

 

[zinfamous]

Originally posted by: FoBoT
;

yeah, that pissed me off too, today

who approved of this update?! :|