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
When you think about it, everything that we see is technically in the past. Mind you, if you are looking at something only a few feet away it only took the light you are seeing the tiniest fraction of a second to arrive but there actually is a very very very tiny delay. To add to this, there is a delay between when your eyes receive the light and when the signals carrying this information arrives in the sight centers of your brain. Add another incredibly tiny fraction of a second to actually process the signals and convert them into the image that your brain “sees” and you’re now running a few millionths of a second behind “real time”. But given how fast our brain actually reacts to events this “time delay” is negligible and we consider what we are seeing as being “immediate”.
As the distance increases, this effect slowly increases. At the distance between the Earth and the Moon you are up to a delay of around a second. Still pretty close to “real time” for most of us so we would not really notice much of a delay. The Sun is about 8.5 “light minutes” away, meaning that the light you are seeing left the surface of the Sun over 8.5 minutes ago. If the Sun exploded this very second no one would realize it for 8.5 minutes. And so on. As you get to “interstellar” distances the time it takes light to travel expands rapidly. The nearest star to the Sun is over 4 “light years” away, so if it exploded this very second we will not see the event for another 4 years.
The satellite that NASA is using is tasked with examining objects that are 13 billion light years away. What we are seeing when the satellite looks at these objects is events that happened 13 billion years in the past. It is very possible, even likely, that those stars and planets no longer even exist today, but depending upon how long they survived past the moment that we are currently observing, it may be millions of years or more before the light arrives to allow us to finally be able to see their “deaths”, even though the actual events have already happened.
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