why does the Sun look big at Dawn and Dusk?
465481
It only looks big because you have other things to compare it against, like trees and houses and things.\nNext time there's a full moon, try it with that (it's easier to observe). When it is low in the sky and looking big, hold your arm out full-length, stick out your thumb and compare your thumb nail size against the moon. Six hours later, when it is up high in the sky, do the same trick and you'll see it is actually the same size.
661394
it occurs when solar radiation from the sun interacts with the magnetic field around the Earth (its strongest around the poles..so thats why theres a northern..AND southern lights...and no "Middle" lights lol)\n\ni can't wait to see it some day
530719
During daylight the sky has the appearance of an opaque blue surface, but this is the result of the air scattering sunlight. [1]There is no "blue object" above the earth in any normal sense, so it is hard to say what object the sky is. The sky is thus sometimes defined as the denser gaseous zone of a planet's atmosphere. At night the sky has the appearance of a black surface or region scattered with stars. But if we then say that the sky is the entire visible universe, it would not be the same thing we see during the day. The color of the sky is a result of diffuse sky radiation.\nDiffuse sky radiation is solar radiation reaching the earth's surface after having been scattered from the direct solar beam by molecules or suspensoids in the atmosphere\nThe sky is blue partly because air scatters short-wavelength light in preference to longer wavelengths. Where the sunlight is nearly tangent to the Earth's surface, the light's path through the atmosphere is so long that much of the blue and even yellow light is scattered out, leaving the sun rays and the clouds it illuminates red, at sunrise and sunset.
48821
It is an optical illusion.  The moon appears to be larger because you are comparing it to smaller things.  They have taken very careful measurements and determined that, in fact, the moon is the same size no matter where it is in the sky.\n\nThere was a theory for a while that the moon appears larger because objects in general appear larger when you look horizontally at them.  I have to admit I have a soft spot for that theory no matter how hare-brained it may seem.  After all, your heart jumps when you look down (and maybe up?) a long cliff, but you don't get the same effect when you imagine the same situation in a horizontal context.  I've heard this theory was mostly debunked, so I can't seriously suggest it anymore.
1127386
I can think of 2 possibilities.  One is when they use an occulting disk to block out the Sun (because it is so bright), so you see a black disk, and then you can see the space around the Sun.  They do that to look at the atmosphere around the Sun.  Take a look at the first link below.\n\nThe other possible answer is that the photographs are not taken in normal visible light but some other wavelength.  in the second link, there is a picture where the Sun's 'normal' surface looks dark.  The caption helps explain it.
550742
Dawn or as the sun rises.
379155
The moon looks bigger when it is closer to the horizon. \n\nIt's an optical illusion. Our brain makes the focal point (the farthest point) of a perspective appear larger. If you look at the moon by turning your head upside-down, the moon will appear to be normal size.
31265
Frosty is right, Otisabi is wrong. The round shape of the atmosphere bends the light. You also get a reddish taint to the moons colour when it's close to the horizon. This is due to the red part of the light reflected from the moon hitting your eye, while the rest is into space. If you've ever looked into a round fishbowl you'll see how it distorts light to make things look larger.
989266
for the same reason ours get bigger or smaller: to let in more or less light depending on the environment
680880
We see the blue sky because of Rayleigh scattering.  Short wavelengths (blue light) are scattered more than long wavelengths (red light).\n\nAs the sun dips below the horizon, it doesn't get dark immediately.  We still see some light, this is twilight.  At night, even though sunlight is scattered, it doesn't scatter all the way around the globe.  Hence you eventually observe a black sky.
326074
Braxton Paul has two out of the three reasons.\n\nOne has to do with frames of reference.  There are objects on the horizon to which the Sun or Moon can be compared.  Try holding your finger up against the Moon when it is rising or setting vs. when it is overhead.  \n\nAnother as to do with the nature of the atmosphere, which makes the Sun or Moon look larger when their light passes through more of it.  \n\nBut Carl Sagan discussed an experiment carried out in a darkened planetarium dome, where it was demonstrated that even without reference objects, we tend to perceive objects at the horizon as larger than objects overhead.  We have no explanation for why this is so.
581391
as the earth spins on it's axis the distance from any one given point on earth to the sun changes throughout the day. Near midday the sun is directly above you and closest to you, thus it is very bright. As the day goes your point on earth spins away from the sun, making it further away, and you are also seeing it through all the dust in the atmosphere, making it less bringht and appear yellow/red.
569674
you also need your latitude.  \n\nThink about it, if you were at one of the poles, sun-rise and sunset would be drastically different.\n\nYes, There is a formula.\n\nHere's the answer in positional astronomy...
239616
two factors, diffraction being one.  The other is that you rarely have a a small source.  The sun appears small, but is significantly larger than the Earth.  Therefore, on any edge shadow, you have light rays coming from both sides of the sun as well as the middle.  Since their trajectories are not parallel, the edge gets fuzzier farther away from the shadow because the rays are able to spread out more once they're past the actual edge casting the shadow.
1133392
On the day of summer solstice, the sun is at it highest point in the sky, traveling the highest path across the sky. When the sun is to the side, there are shadows because a part of you is blocking the sun for something else. However, when the sun is right above you, the only thing you are blocking out from the sun is the place that you are standing in. Barely any shadows appear. The only shadows that appear are just the ones underneath you.\n\nHope this helps!
1055537
Here is something interesting to think about: When you look at the sky at night, it is black, with the stars and the moon forming points of light on that black background. So why is it that, during the day, the sky does not remain black with the sun acting as another point of light? Why does the daytime sky turn a bright blue and the stars disappear? \n\nThe first thing to recognize is that the sun is an extremely bright source of light -- much brighter than the moon. The second thing to recognize is that the atoms of nitrogen and oxygen in the atmosphere have an effect on the sunlight that passes through them. \n\nThere is a physical phenomenon called Rayleigh scattering that causes light to scatter when it passes through particles that have a diameter one-tenth that of the wavelength (color) of the light. Sunlight is made up of all different colors of light, but because of the elements in the atmosphere the color blue is scattered much more efficiently than the other colors. \n\nSo when you look at the sky on a clear day, you can see the sun as a bright disk. The blueness you see everywhere else is all of the atoms in the atmosphere scattering blue light toward you. (Because red light, yellow light, green light and the other colors aren't scattered nearly as well, you see the sky as blue.)
462021
It doesn't GET any bigger than it is, it just LOOKS bigger because it really IS nearer\n\nBecause its distance from the earth varies as the orbit is not a circle, as you asssume, but an ellipse (oval).\n\nThe furthest distance from the earth that the moon reaches in any orbit (lunar month) is called the APOGEE and the nearest distance it approaches in that orbit is the PERIGEE.\n\nIn the table below the distances are in kilometres, measured from the centre of the earth to the centre of the moon.\n\nJust gone:\n\nMar 13  APOGEE 406272 km \nMar 28  PERIGEE 359169 km\n\nComing up soon:\n    \nApr  9 APOGEE 405549 km    \nApr 25 PERIGEE 363735 km  \n\nThe earth's orbit round the Sun is an ellipse too, and the nearest distance in any one orbit (year) is called PERIHELION and the furthest distance in that orbit is called APHELION.\n\nHelios is the Greek word for the sun and Peri- and Ap- are prefixes meaning near to and far from. The sun looks correspondingly smaller at aphelion and larger at perihelion.  \n\nSometimes eclipses of the sun are not quite total if the sun is bigger than usual (near or at perihelion) and the moon smaller than usual (near or at apogee).\n\nThere is a more pronounced variation in the distance between Earth and Mars than either the variation in Sun-Earth or Earth-Moon distances. Mars looks a lot brighter and a lot dimmer as a consequence, at these times.\n\nTo visualise why, think of a clock face. The sun is in the middle of the dial. The earth is on the tip of the hour hand and Mars is on the tip of the minute hand. When the time on the clock face is midnight, five past one, ten past two etc earth and Mars are at their closest. When the time on the clock face is 12.33, 1.37, 2.43 etc Earth and Mars are at their furtherst apart, Mars being the radius of an earth orbit plus the radius of a Mars orbit away, beyond the Sun.\n\n(This too-simple model assumes circles not ellipses and assumes that Mars years are twelve Earth years, where in reality Mars years are only about twice an Earth year. But it gives you a general idea.)