A star (our sun )is part of a galaxy.
A planet (earth) orbits a star.
A moon (our moon) orbits a planet (earth)
One light year is the distance travelled by light in a year.
It takes light from the sun 8 minutes to get to the earth.
It takes 4 light years for light to reach the nearest star (alpha centauri)
It takes light 100,000 light years to get to the edge of our galaxy.
There are two types of telescope ,the refractor and the reflector.
The refractor works by light bending or refracting.
The reflector works by light reflecting.
The refracting telescope consists
of two convex lenses.
The objective lens collects light
from distant objects such as
planets and stars. It forms an image of them.
The eyepiece lens then magnifies this image.
Use can be made of light ,radio and micro waves from the electromagnetic spectrum.
Radio waves are detected by large curved dishes similar to the dish aerials in T.V. systems