Astronomy / Physics Question

[demien2k5]

It does if a blind person is nearby.

If a blind person is killed by a falling tree in the woods because he didn't see it coming, and there is no else there to see it happen, will life insurance still pay?

 

[demien2k5]

anyone have any ideas on what might happen if an object gets too close to uranus?

ymmv

 

[T.O.tourist]

If a blind person is killed by a falling tree in the woods because he didn't see it coming, and there is no else there to see it happen, will life insurance still pay?

If the adjusters determine that the tree was not tampered with. Yes

 

[Spacealien2]

Okay, thanks for all that.
I was also speculating if maybe the fabric of spacetime itself is orbiting around the sun in a counter clockwise motion and, if this is so, maybe the earth would become like a ball tossed onto a spinning roulette wheel and therefore generate new counter clockwise rotational speed around the sun and fall into a new orbital position somehow that keeps it from falling all the way into the sun.

It would happen. But it wont prevent the earth from hitting the sun. http://en.wikipedia.org/wiki/Frame-dragging

 

[oil&gas]

Anyone have any ideas on what might happen if an object gets too close to Uranus?

The closest approach when Voyager 2 (launched in 1977 by NASA)
passed by Uranus in 1986 was 81,500 km. Apparently the space probe
came out unscathed and is still in operation.

Voyager 2 is exiting the solar system at a velocity way below
the escape velocity of Uranus. If it moved too close it could be
sucked onto the surface of the planet.

 

[FAST]

No laughing please

OK,...another question,...could some one explain to me why is it that when you look up at the night sky on 3 different planets, earth, our moon, and mars, the stars appear to be fixed and not just streaks in the sky.

I can see this being the norm for 1 planet, but all 3,... that I know of anyway.

FAST

 

[blackrock13]

OK,...another question,...could some one explain to me why is it that when you look up at the night sky on 3 different planets, earth, our moon, and mars, the stars appear to be fixed and not just streaks in the sky.

I can see this being the norm for 1 planet, but all 3,... that I know of anyway.

FAST

I suspect they will look much the same except in a little different point in the sky. Considering the closest star is ~4 light years, ~40 trillion kms away, the relative change from one moment to the next is very very very small. Try sometime lapse photography at night and see what you get with 1, 2, and four minute exposure and you aren't staring at the star(s) for that long a time frame. Your third choice, Mars is only ~50 million km away, a fraction of the distance to the nearest star.

 

[blackrock13]

It has nothing to do with how far away they are. It's all about the rotational periods of those bodies.

The distance would affect the measurable change they have. Much like shooting stars, yes I know they are not stars. They appear to streak because they are very very close and going through the earths atmosphere.

Rotational period?

 

[FAST]

Dizzy

Why would they appear as streaks? None of those bodies rotates that fast, if that's what you're talking about.

I should have clarified,...the earth moves through space at a little over 1000 MPH, and I realize about it's axis also,...which I thought is why the stars appear to be stationary,...but I am surprised that ALL 3 planets have this same synchronization !

Or am I missing something here.

FAST

 

[blackrock13]

I should have clarified,...the earth moves through space at a little over 1000 MPH, and I realize about it's axis also,...which I thought is why the stars appear to be stationary,...but I am surprised that ALL 3 planets have this same synchronization !

Or am I missing something here.

FAST

All three of those bodies are very close to each other compared to how close they are to just the closest star, simple trigonometry. The vantage point would be nearly the same relative to that star.

 

[blackrock13]

No, you're confusing the movement of the stars relative to each other and our sun with the rotation of the earth. And what do "shooting stars" have to do with anything?
Sorry, but if you don't know what "rotational period" is, and use phrases like "shooting stars", you shouldn't be attempting to contribute.

I didn't say I didn't know what it was, just questioned how it answered FAST's question more completely.

So enlighten us.

 

[FAST]

Dizzy and confused

Ah. Well, the movement of the earth through space is meaningless - everything is relative. The stars appear to move in the sky because the earth rotates, but it only rotates with a period of a day - pretty slowly. Why doesn't one of those three bodies rotate much faster? Just 'cause.

OK,...so if the earth did NOT rotate about its axis,...the stars would still appear to be stationary ???

FAST

 

[blackrock13]

No, I'd rather just ignore your ramblings, which is what I advise others on this thread to do.

Sure, well done.

 

[blackrock13]

Imagine the solar system being inside a huge globe, right at the center. Paint the stars, excluding the sun, on the interior surface of that globe. Now spin the earth on its axis. This is what causes the stars to appear to move in the sky.
Relative to our position at the center of that globe, the stars barely move at all "on their own" relative to us. At least over the course of our lifetimes.

That is basically what i said. Glad to see you agree.

 

[blackrock13]

You figured out what a rotational period is yet?
Thanks, but let the adults talk now.

I knew what it was before, but just wanted to see you explain how it mattered. Not a hard thing to understand. I'll remember to dummy down my question for you next time.

 

[blackrock13]

Yeeeeah. Sure. So, you're either mentally challenged or just a kid. Either way, I'm just gonna assume you have no idea what you're talking about, and refrain from further insult.

If anyone else has any physics or astronomy questions, please don't hesitate. Rest assured, there's someone in here who is actually educated in these fields and who can answer your questions.

Yet you couldn't comprehend a simple comment. I have little doubt you know more than most in those areas, but you also perform nose in the air shovel hits face really well.

I hear that this was you at the planetarium on a school trip back in the day.

[video=youtube;42USBCK8gm8]http://www.youtube.com/watch?feature=player_embedded&v=42USBCK8gm8[/video]

 

[blackrock13]

You know, it's okay to just admit you don't know as much as someone else every so often? Give it a try sometime.

I have often said so and certainly didn't say I knew as much as you. Again another example with understanding simple english.

 

[blackrock13]

(Still waiting for you to admit you don't know as much as me - understanding simple english, eh? )
Okay, Shooting Star. Whatever you say. Last word to you. Aaaaaaaand GO:

Okay you know more than I, feel better now? Not that it was ever the question. Now put the shovel away, recess is over.

 

[red]

Assuming the earth just stopped and then started falling in towards the sun, if you zero centripetal acceleration, it would take about three months for the earth to travel the 1 AU required.

And you're not taking about rotation, you're talking about revolution. The earth doesn't ROTATE around the sun, it REVOLVES around it. It ROTATES on its own axis.

(a) At any one point in time, it's VELOCITY is tangential to its path, as with all circular motion. In reality, THERE IS NO FORCE opposing the force of gravity. Because the earth is moving in a roughly stable circle, it's centripetal acceleration is equal to the force of gravity exerted on it by the sun. There is no countervailing force - the earth is, classically, accelerating towards the sun as it revolves around it. Its velocity is what it needs to be to keep it in orbit.

It's actually much simpler than that. You know exactly how fast the earth revolves around the sun - it makes a circuit of two times pi AU (astronomical unit - the distance from the earth to the sun) per year. The formula for centripetal acceleration is acceleration equals velocity squared divided by the radius of the orbit (again, 1 AU). So, if you just stopped the earth in its tracks, it would accelerate towards the sun at this rate. Distance traveled equals one half of acceleration times time squared - d=at^2/2. Just do the math from that point, and you get t=(1/2*pi^2)^0.5 in years. That's about .22 years. Don't need to know anything about the relative masses, since you can use the orbit of the earth to calculate its centripetal acceleration.

great answer. thanks- it was an interesting question

Extremely improbable. But, hey, you've just stopped the Earth in its tracks - feel free to throw it at whatever celestial body you like!

LMAO.

 

[red]

I'm just an amateur with curiosity.

.

that's how most of the porn on the internet gets made