Sun expansion/contraction?

Question

Hello,

I have noticed that at certain times of day and at certain points in the sky the sun will appear to be bigger or smaller. For the most part, in the morning at or near sunrise and in the evening near sunset, the sun will generally look bigger than it is when it is directly overhead or close to it. Why is this?

Thanks,
Ryan

Answer 1

I like all kinds of illusions. One that is good to explain the Moon/Sn size illusion is the distorted room illusion. The room is not square but all the lines make is seem so when viewed form a certain point of view. So, a person standing in the small end of the moom appears to be very large while a person standing in the large end of the room appears to be small.

It all has to do with what our brain expects to see when looking at a scene. When the Sun/Moon is at the horizon, it is next to tiny things that our brain knows are far away, so it sees the moon as large. In the sky there are no lines of perspective or little objects to compare it too and the Moon/Sun appears to be smaller.

Actually the Sun/Moon are the same size throughout their arcs, although if they are very near the horizon there is some atmospheric distortion caused by the air's ability to bend light slightly. But that effect is only at the horizon. It isnot what makes them appear large as they rise above the horizon.

;-D You can easily mesure the size of the moon with something held at arm's length or look through a tube which blocks out the other visual cues.

Answer 2

A way to understand what happens in the Sun in Space would be to compare an electron to the barry center of the Nucleous of a hydrogen atom.
The Nucleous would be analogous to the Our Galaxy and the electron would be anologous to the Sun.

When the electron loses mass ,its average radius vector decreases. If by external radiation we add mass to the electron the opposite occurs.When the Electron is closer to the nucleous it can almost reach the Speed of light . When it moves far away from the Nucleous its speed can reach only
10 % of light speed.

If the Sun is receiving more mass than it receives then the Relative velocity to the Galaxy would be reduced and the radius vector would increase.

If the Sun is losing more mass than it receives than its radius vector would decrease and it relative velocity of its orbit around the Galaxy would increase.

As far as your observation of the sun on the horizon appearing bigger at times and smaller at other times can be expained as follows;
The Earth folows an eliptical orbit relative to the Sun at one focus.
So the Earth in the winter time is closer to the sun;therefore its perspective size appear bigger than in the Summer time when the the radius vector is further away.

Its very vely simple.

Answer 3

There is a good explanation on the website http://www.straightdope.com/classics/a2_110.html

It goes into the history of the debate on why the Sun/Moon look bigger on the horizon.

TMD

Answer 4

The solar, the sand and the wind have had some, yet no longer a great deal of weathering result on the Egyptian Pyramids over the years. they don't seem to be as comfortable as they're believed to have been whilst they have been first equipped. The pyramids are the oldest man made structures in existence. They date returned 4,000 to 5,000 years.

Answer 5

Atmospheric conditions cause this illusion.