I saw a post on reddit saying NASA has a telescope that is able to see the creation of planets and stars from 13 billion years ago. How can that work?
Link to post: https://www.reddit.com/r/interestingasfuck/comments/ke2p2r/nasa_is_about_to_launch_a_telescope_that_can/?utm_medium=android_app&utm_source=share
In: Physics
What they’re talking about is the light that Hubble (or any telescope really) is seeing started on its journey billions of years ago. Light has a finite speed… the speed of light. A light-year is literally the distance that light travels at this speed during one our Earth years.
So the light that we see from other parts of just our own galaxy have taken years to arrive at where the Earth is in space. But they’re considered a snapshot from the past because its light from where those stars _used to be_ when they emitted that light. In actuality, those stars have moved bagillions of miles away by now.
Because other other galaxies are thousands or millions of light years away, and most galaxies in the universe are flying apart from each other – at speeds approximating the speed of light – the light that we now, here, from those galaxies has been travelling for… millions of years.
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