The reason we are able to see the wonderful world around us is because of the light being reflected off of their surfaces. But as distance increases the time taken for that light to reach our eyes takes time. I’m not talking about switching ON a lamp in your room but of the stars and planets and other objects in our universe.
Our Sun is 93 million miles away from Earth. The rays of the sun takes 8 mins and 20 secs to reach the Earth. This means that anything that may occur on the sun at this very moment we wouldn’t be aware of until 8 minutes and 20 secs from now.
Anyone who travels from Earth towards the Sun will be seeing the Sun in the future compared to someone observing the Sun from Earth.
The distances between the planets and the stars are measured in light-years for a reason. The light simply takes that many Earth-years to reach the Earth. Tells you how big our universe is.
Like I had mentioned before the sun’s rays take about 8 mins and 20 secs to reach Earth. This can be expressed as the Sun being 8.2 light-minutes away from Earth.
1 Light-year is about 5.88 trillion miles.
After the Sun, the nearest star to the planet Earth is Proxima Centauri, that is about 4.37 light-years away. It takes about 4.37 years for light to travel from that star to Earth for us to be able to see it. We are essentially observing what Proxima Centauri was like 4.37 years ago. We are, in simple words, looking back in time.
Someone looking at Earth from 170 million light years, from the Centauras Cluster (Cluster of Galaxies), may be watching the dinosaurs walk around.
The further you observe the universe through your telescope, the further back in time you travel.
