why things appears as small when see from long distence?
529925
This question is miscategorized.\n\nSpecial Education is about the education and parenting of children with special needs.
923222
The smallest anything can be is called Plank length and it is approximately 1.6 × 10 (to the -35th power) meters.  \nAssuming "we" is the earth, we are very small compared to the size of the universe.  The "volume" of the observable universe is about  1.9 × 10 (to the 33rd power) light years, and the earth has a volume of approximately 8.2 x 10 (to the 12th power) miles, or 4 x 10 (to the -26 power) of a light year.  The universe, then, is about 4.7 x 10 (to the 58th power) times bigger than the earth.
658780
We observe four dimensions everyday, three spatial and time.\n\nBut...theories such as string theory predict that the space we live in has in fact many more dimensions (frequently 10, 11 or 26), but that the universe measured along these additional dimensions is subatomic in size. As a result, we perceive only the three spatial dimensions that have macroscopic size.\n\nThis is not so strange as it sounds, which I'll show with an example. Imagine you are in an airplane, flying over sea. Seen from a height, the sea looks flat, two-dimensional. But when the plane looses height we start to perceive the waves, that move in a third direction we could see before.\n\nThe universe could be the same. Four macroscopic dimensions and a few more, hidden ones. We can only perceive them for instance, by the small effects their existence might have on subatomic particles.
24731
You see in the past anytime you look through a telescope (or any distant object), as the light that is reaching your eye left the object a few seconds, minutes, or even years ago. You are seeing the object "as it was" when the light left it. If a star is 10 light years away, you are seeing it as it was 10 years ago, not as it is now. If it were to disappear, we wouldn't know about it for 10 years.
90131
In reality, the Sun is always the same size! The illusion of difference in what appears to be a difference in size can be explained by, where on the planet you are viewing it from(are you viewing the rising and the setting sun in the East? The west is farther away when you watch it set), the Seasons(distance from the Earth), the angle at which you are viewing it from, atmospheric inconsistancies and plain old Optical illusions. Take your pick or combination of the above.
406370
More light is needed as the magnification is increased since the size of the hole of the objective lens decreases. Try it!
869442
Objects can't change their brightness faster than the time it takes a light signal to travel across their width.  Quasars change their brightness very fast, so we can infer they are very small for their energy output.
700811
This is because the earth is so large - relatively - as compared to our size. While standing on the earth, we are unable to see the change in slope of the earth's surface. Our line of sight will make it seem as if the earth is flat, but our sight is really a tangent, being very close to the line of the earth's surface. An example of this is when look out at the ocean, and see the masts of a ship first in the distant horizon. This is because at that distance, the curve of the earth is more prominent.
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.
481479
Strings are indeed very small but I'm going to have to agree with the neutrino answer here. They are so light that they were thought to have no mass until the late seventies (I think).
289555
The Moon's apparent size is an illusion based on its apparent proximity to other objects (stars, mountains, trees, buildings).  The Moon alone in the "middle of the sky" can seem quite small, but a few foreground objects of the correct relative proportion will impart the illusion.\n\nTo "correct" the illusion, hold your thumb up at arms length and compare it to the moon at different times of the day and night (visibility dependent, of course).
957189
This is an optical illusion - It has to do with how the brain interpretes things that are in front of you compared to above you. Try this for yourself: Take a dime and hold it out in front of you to cover the moon. You will see the moon is the same size both in front and overhead.
220589
For all we know there is nothing "outside" the universe, so obviously no way to look "at" it from any "outside". That way there is no way to compare the size of it, why you could probably say, the universe is infinitely small. There is a mathematical smallest size, called the Planck-Size. That is just where space ends to be space, so there is no inside. As simple as that. You don't need to invent any kind of god to think about those things.
752656
The size of an object you can resolve with an optical system has a theoretical limit given by the wavelenght of the light you're using divided by the diameter of the optics multiplied by 1.22. If you plug the numbers in you find for a 1 foot diameter optical system at visible light (~400 nm) at an altitude of 100km, the smallest thing you could see is on the order of a foot, give or take (rough calculation). You could definitely not read a postage stamp or a wrist watch. Maybe a license plate with some bigger optics, but this is ignoring all sorts of atmospheric scintillation which screws things up.
111961
It is called the Moon Illusion. When the moon is closer to the horizon it looks larger than when it is high in the sky.\n\ncheck this out: http://facstaff.uww.edu/mccreadd/
626305
Because you can read/see something better through a smaller hole. It's just like making a small circle with your index finger and thumb, if you look through it you can see a lot better!
510510
I would have to go with the Planck length on this one, which is a millionth of a billionth of a billionth of a billionth of a centimeter!  \n\nThe reason I say this: According to String Theory, strings are that long, and they are the fundamental building block of all matter.  Therefore, nothing exists that is smaller than that, so it is useless to have a smaller measurement.