Telescopes

Galileo Galilei

He was an Italian astronomer, physicist, engineer and a polymath, He used telescopes to observe Jupiter's moons and was able to make many advances with telescopes.

Light

Light is a form of energy which travels in straight lines. It can be reflected and refracted and is the visible part of the electromagnetic spectrum. The spectrum of visible colours is mixed to form white light.

Reflection and refraction

Reflection is light bouncing off a surface and travelling in a new direction.

The normal is an imaginary line that is perpendicular to the surface, and the angle of incidence is the angle between the incident ray and the normal. The angle of reflection is equal to the incident ray from the normal's perspective. At the point of incidence, the normal, incidence and reflected ray all lie on the same plane.

Refraction is the bending of light as it passes through one transparent substance into another. It is caused by a change in the speed of light as light travels from one medium to another medium.

Light and wave theory

Light acts both like a particle and a wave at the same time. Light waves are electromagnetic waves as they are made up of both electric and magnetic fields. They oscillate perpendicular to each other. They ate transverse waves as they oscillate in the direction traverse to the direction of wave travel.

Focal point and length

The focal point is the point in which all light rays are focussed into through a lens. The focal length is the distance between that point and the lens. This is according to Lewis's confusing explanation, so don't blame me.

Aperture

A telescope's aperture is the diameter of its objective lens.

Reflector telescope

A reflector telescope uses a mirror to gather and focus light. Due to the large distance between the Earth and celestial objects, the light is essentially parallel to each other. The mirror has a parabolic shape as a result, focussing all of the light rays onto a single point.

Their advantages over refractor telescopes are that they do not suffer from chromatic aberration as all wavelengths reflect in the same way and that they are also cheaper than their refractor counterparts of the same size.

Refractor telescopes

Refractor telescopes refract light from celestial objects. They have two lenses.

It rarely needs cleaning as its lenses protect its interior from the outside environment. Its images are sharper and steadier than reflector telescopes of the same size. However, they all suffer from chromatic aberration.

Compound telescopes

Compound telescopes are a combination of reflector and refractor telescopes.

Reflection

Today I learnt about reflection and refraction and how they are used in telescopes to magnify celestial objects. This lesson was slightly more fun as we were able to use lasers on glass and mirrors.

One positive thing so far is that there is only one negative thing. One negative thing is that the lessons are confusing and difficult to follow because the "summaries" are long.

I attempted to summarise the summaries' information based on what I can understand.

 

I will apply what I have learnt to not make boring and confusing lessons in the future.