How does the telescope make it possible to see distant objets?

Answer 1

A telescope works like a huge eye. The human eye, in the dark, is only about 7mm in diameter fully dilated. An easily-affordable 6-inch reflecting telescope is 152.4mm in diameter. This works for refractors, too, but they are much more expensive per inch of diameter. Therefore, the telescope is 21.7 times larger in diameter. But, there is more to it than this! The area of the eye is 76.2 square mm. The area of a 6 inch telescope is 2026.83 square mm.

From, area of a circle = pi*r^2, (Note -- Radius, not diameter!) knowing that 1 inch = 25.4 mm, From this, 18241.51/38.48 equals 474.05, making the telescope have 474.05

times more light grasp than the human eye. Each magnitude of star is 2.5 times that of the one above or below it, progressively. Therefore, we can see far dimmer stars with the telescope than with the unaided eye, between 7 and 8 times dimmer on the magnitude scale.