[Guest]

Ok I've always wondered this and since I became acquainted with this site I'm sure at least some of you smart fellows might be able to help me out.

Say you're riding in a car and you look up at the sun, not driving cause you will see spots when you look back at the road and it will screw with your vision so don't do it while driving =P

Why does the sun seem to follow you?

And if you can answer that question maybe you can answer this:

Why does an aircraft seem to move faster if you run the same way it's moving and slower if you run the opposite way?

[Guest]

First cos it is so far away that a cahnge in angle is not gonna effect the perspective like converging lines over a mile varied by 1 inch

second coz you have a comparrison - I drove into London from Heathrow airport and it looked like the planes hovered as they came towads the airport

[akaslickster]

Ok I've always wondered this and since I became acquainted with this site I'm sure at least some of you smart fellows might be able to help me out.

Say you're riding in a car and you look up at the sun, not driving cause you will see spots when you look back at the road and it will screw with your vision so don't do it while driving =P

Why does the sun seem to follow you?

And if you can answer that question maybe you can answer this:

Why does an aircraft seem to move faster if you run the same way it's moving and slower if you run the opposite way?

The sun is so large that it always seems to stay near you but the many miles of difference that you are away, do not matter because of its enormous size. As it sets it will appear larger usually, and gives you the mental notion that it is getting closer to you. That's just my opinion. There is a physics type of explanation for the scientific reason. Aircraft is also dealing with momentum, I guess.

[Guest]

I think the Aircraft thing is because you can see the distance away the aircraft is, and so you mind trys to make sense of it.

[Guest]

The sun seems to follow you because it is so vast and there are millions of miles of distance between you and it, so unless you drive very fast and far, it will seem to always be in the same place.

[Brandonb]

Ok I've always wondered this and since I became acquainted with this site I'm sure at least some of you smart fellows might be able to help me out.

Say you're riding in a car and you look up at the sun, not driving cause you will see spots when you look back at the road and it will screw with your vision so don't do it while driving =P

Why does the sun seem to follow you?

And if you can answer that question maybe you can answer this:

Why does an aircraft seem to move faster if you run the same way it's moving and slower if you run the opposite way?

Question 1 seems to have been answered pretty well, but I have a different answer for #2.

It's all about the background.

If you are going the same way (along the side) as the aircraft, or any other moving vehicle, you are seeing the vehicle at nearly a static placement in your line of sight. While you are looking at the vehicle, the background becomes a blur whizzing by, which gives a very vivid perspective of motion.

If you are looking at the same vehicle from head-on, or from behind (I assume this is what is meant by "opposite way"), then the vehicle will appear nearly as static in your line of sight as the background. The only way to observe speed from that perspective is to judge how quickly the vehicle seems to grow or shrink when you view it moving towards or away from you. Either way, as I said before, the variance between the vehicle and the background is minimal, which is what makes it not appear as fast as a side view does.

Edited August 23, 2008 by Brandonb

[unreality]

Like when you look out of the side of a car, and see stuff whizzing past, but look straight forward and everything is more static

[Brandonb]

Like when you look out of the side of a car, and see stuff whizzing past, but look straight forward and everything is more static

Right! Now, in your head, set both of those perspectives that you mentioned as backgrounds for another fast moving vehicle (like an aircraft). Notice the difference in how well you are able to observe the speed of the vehicle. The speed is much more apparent when you can contrast it against a background that whizzes past.

[Guest]

Like when you look out of the side of a car, and see stuff whizzing past, but look straight forward and everything is more static

Lol so you're saying that if someone was as high as an airplane, lets just say you're in a hot air balloon (you might need an oxygen mask I'm not sure how high you can go without needing an oxygen mask), and you aren't really moving. But you see an airplane go by, or something that moves about as fast but won't kill you if you get too close to it, you're gonna see it move a lot faster than you would have if you were on the ground and saw it move?

[Brandonb]

Lol so you're saying that if someone was as high as an airplane, lets just say you're in a hot air balloon (you might need an oxygen mask I'm not sure how high you can go without needing an oxygen mask), and you aren't really moving. But you see an airplane go by, or something that moves about as fast but won't kill you if you get too close to it, you're gonna see it move a lot faster than you would have if you were on the ground and saw it move?

Oh, I thought you were asking about a front/back view vs a side view. In the example that you suggested, it would depend on how close you were to the plane from each angle, and how much stuff was on the other side to suggest motion and speed. A plane passing in front of clouds will seem to be moving faster than a plane flying through clear skies at the same distance and speed.

Assuming that the vehicle's speed and background remain constant, another thing that will effect your perception of speed is the distance that the vehicle is from you, and the vehicle's distance from the background. In the situation you suggested, contrasting an 'up-close overhead view' against a 'distant ground view', the significantly closer view will make the vehicle appear to be moving faster, no matter what the background is. This is because of the time it takes for the vehicle to change its angle relative to your view point. (similar to your 'Sun' question) If you are on the ground looking up at a high-altitude plane, it will take much longer for the angle to change relative to your position, than it would if you were merely a few yards away in a hot air balloon.

Again, it depends on whether you are asking about the variance pertaining to a change in viewing distance, or a change in viewing angle.

Has this answered your question?

[Guest]

Yeah pretty much...