Measure distance in light years. One light year is the distance light travels in one year. Visible light travels at 300,000 km/second in space. It takes a long time for light to reach us from distant stars and planets. Telescopes are like time machines, allowing us to see what things looked like in the past.
Expanding Universe
Across the visible Universe, galaxies are found to be moving away from each other - rather like spots on an inflating balloon. However, it is actually space that is expanding. The further away from us galaxies are, the faster they seem to be moving.
Comments
Post a Comment