This is more for my girlfriend than myself.
I’m trying to explain to her how the image of Stephans Quintet that the James Webb Telescope recently took, is what those galaxies looked 300 million years ago, as they are 300 million light years away.
I’m having a lot of trouble wording it in a way she can understand. She has never really researched astronomy like I have, and she doesn’t understand why I’m so excited about these images.
I’m hoping you guys could help!
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Imagine someone drops a letter off for you today. That letter came from the opposite side of your country, and took a week to get to you. Whatever that letter says is a week old. Whatever information you get from that letter, it tells you about the condition of the sender one week ago.
Light is really really *really* fast, but it still takes time. It just arrived to us *today*, but it left the stars millions of years ago. All the information that light carries comes from that time.
You watch fireworks? You know how the boom is delayed because sound is way lower than light? It’s like that. The sound is a second or two old by the time it reaches you. With really big distances, light works that way too. If the sun explodes, we would see it until a little over 8 minutes later, so when we see the sun, it’s what the sun looked like 8 minutes ago. Further away, the longer it took the light to reach us.
Say you take a picture today, but that picture takes one million years to develop because the picture (the light) isn’t there yet. In one million years, the picture will be fully formed and you can look at it clearly, but it will be a picture of something from *a million years ago*.
Now imagine instead of a million years, it’s a picture from a billion years, or more, and took that many years to develop so you can actually see it.
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