Digital photos created with digital cameras are made up of dots called
pixels.
Pixels are arranged in
horizontal rows and
vertical columns, and as so they create a
rectangular image.
If you
multiply the number of
horizontal and
vertical pixels you’ll get the
resolution of an image, but, because we are talking about really big numbers, it is used increasingly popular expression
megapixels.
Common values are 3, 4, 5, 6...megapixels. The higher the number, the better and more detailed image is.
But, no matter how many megapixels has the camera that you have used or intend to buy, its resolution is null according to that used for
telescopes -
15 megapixels and more.
Champion among them is the telescope in
Hawaii, which is called “
Megacam Wide Field.” The astronomers use it to photograph supernovas (dying stars) in amazing resolution of
340 megapixels.