The Importance Of Telescopes

Telescope is a tool that allows people to see objects from far away, beyond human vision, this helps a lot in researching for scientists, especially for astronomers to discover new stars, planets and galaxies. The first known telescope was introduced in 1608 by Hans Lippershey. Telescopes are an amazing tool, they come in a variety of shapes and sizes, with just a 15cm-long telescope, we can see a penny from 55m away or the world’s biggest refracting telescope at the University of Chicago’s Yeker Observatory has up to 1m lenses so we can unlock the secrets of the universe. There are 2 types of telescope, refracting telescope and reflecting telescope, but today, we are focusing on refracting telescope.

So, what is refracting? It is the change in direction of light rays when passing through the boundary between two transparent mediums with different refractive indices. When light rays travel in a given medium, they go in straight lines,

But, why does it bend, we all know that light can’t be bent in normal situation and light speed in vacuum is c~ 3.0*108 m/s. We also know that different mediums have different density, the more dense, the slower the light speed. Now imagine you and your friend are in the beach and you guys decide to swim all together, so you guys link arms, you are the closest person to the sea and approach the water in a very strong and straight lines, and the moment you reach the water, you realise that it is harder to walk in the water so you slow down and approach the water with an angle relative to the shoreline. You are the first person to slow down as you reach the shore line first while others still remain their velocity because they are still on the shore. After that, one by one will slow down in line, until every passes the shoreline. Because person on one end of the line slows down before the person on the other end so the line of people