What Visible Light tells us about the Universe

Image source: http://www.vkastronomy.com/gallery_clusters.html.en

Some objects in space, like stars, are enormous and are very hot. Although they are very far away from planet Earth, they give out a lot of visible light and so we can see them. Planets in our Solar System don't give out any visible light of their own, yet we can still see them as they reflect sunlight.

Early astronomers made observations about the Universe using just the naked eye – many important discoveries were made this way, however the human eye isn't ideal for viewing objects so far away and so are only useful for mapping their positions.

Telescopes enable us to make observations about distant objects by magnifying an image, so that we can see them in more detail, as well as more objects that are further away than the naked eye can see.

One benefit of telescopes is that we can take photographs using them – this allows us to 'zoom in' to look at objects at closer detail, and makes it easier to monitor the changing positions of objects in space and compare them over time, as well as sharing findings with other astronomers. A long exposure time allows the camera to collect more light, therefore fainter objects can be observed.