With billions of children around the world anxiously waiting for their presents, Father Christmas (or Santa) and his reindeer must be travelling at breakneck speeds to deliver them all in one night. But did you know that light from an object travelling at high speeds changes colour? This is thanks to what’s called the Doppler effect – the way speed affects the length of waves, such as sound or light. When light changes colour due to speed, we call it redshift or blueshift, depending on the direction. If we could catch the colour of Rudolph’s famous red nose with one…
Author: Laura Nicole Driessen, Postdoctoral researcher in radio astronomy, University of Sydney
The days are getting longer and in Australia, the switch to daylight saving time is almost upon us (for about 70% of the population, anyway). But why do we have longer days in summer and shorter days in winter? It’s all about the tilt Earth goes around the Sun in an almost circular orbit. But not everything is lined up perfectly. Earth’s axis is tilted by 23.44 degrees relative to its orbit around the Sun. Imagine Earth’s orbit as a flat frisbee with the Sun in the middle and Earth as a ball on a stick going around the edge.…