Light from Afar Astronomy

When light reaches us after a long, long journey

We begin with the ancient astronomers, who did remarkably well considering that they had nothing but the naked eye and a lot of ingenuity to help them! They determined that the earth is round, and were able to calculate its radius. They progressed to make calculations of the size of the moon and the size of the sun, and obtained very good estimates of the distance from each to the earth.

As measurements became more accurate, astronomers in the Middle Ages were able to make models of the paths of the planets in our solar system. The first models were very complicated, describing the paths of the planets from the point of view of the earth, which was assumed to be stationary, at the centre of the system. Nicolas Copernicus showed that this model was incorrect and put forward a new model with the sun at the centre, and the earth and the other planets in orbit around it.

Light is the messenger which brings us news from other parts of the universe. No information can travel faster than light, but the distances are so great that the news is millions and even billions of years old.

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