Astronomy

[pakigang]

We all know that light from the sun reaches the earth in eight minutes. We also know that it takes thousands and millions of years for light from other stars to reach earht. So the information of the star dying or a new star born or some changes in the galaxy etc, isn't it some that happened millions of year ago and we are just getting the visual on earth now. Even the powerful telescope captures light but then again light enters the telescope so is the same.

What i am trying to say here the all the info of the stars and their position etc. would be different that we are observing that thier actual position ,size, existence and other related things.

One more thing comes to mind is that the light from different star come together, Isn't there a possibility that it collides and give like a misinformation on objects. How can we be sure that what we are seeing is the actual thing and what is illusion of collision, etc.

 

[Peter]

Yes the light that reaches us now is "old". That's a huge part of why it's so interesting and revealing to watch - we're looking millions of years into the past history of the entire universe.

 

[Calin]

We see the distant stars as they were millions of years in the past. However, the distance is too big to see normal stars - we can only see the distant galaxies or some of the most violently energetic stars/pulsars/...
To guard against false "twin" stars, at close distance (like 300 lightyears) one can use the change of seeing angle between summer and winter. One parsec is the distance to a star that changes its position on the sky due to revolution of the Earth between summer and winter by one minute of arc. The astronomic observatories can measure angles up to a hundredth part of a minute of arc, so one can calculate distance to stars up to 100 parsecs in this way (some 300 light years).
What happens at greater distance, I don't know. I know that some stars that were classified as "twin stars" by telescope were confirmed as "twin stars" , while others were found to be at distances of thousands of light years from each other.

 

[JTWill]

Read about a guy that came up with Energy= The mass times the constant squared, the constant is light. He deduced that in order for us to see light that is 100 million years old something happens at the speed of light, Time stops , a photon being the product of a proton and an electron in there release of energy produces a product, sometimes it is visible light. It is the reason he deduced that we see light from the stars in that it does not "burn out" but continues.

 

[JTWill]

Its all relative

 

[Looney]

Originally posted by: pakigang
We all know that light from the sun reaches the earth in eight minutes. We also know that it takes thousands and millions of years for light from other stars to reach earht. So the information of the star dying or a new star born or some changes in the galaxy etc, isn't it some that happened millions of year ago and we are just getting the visual on earth now. Even the powerful telescope captures light but then again light enters the telescope so is the same.

What i am trying to say here the all the info of the stars and their position etc. would be different that we are observing that thier actual position ,size, existence and other related things.

One more thing comes to mind is that the light from different star come together, Isn't there a possibility that it collides and give like a misinformation on objects. How can we be sure that what we are seeing is the actual thing and what is illusion of collision, etc.

Well, for things like collisions and supernovas that explodes, we do see them, and we do identify them as such... because they only last temporary. But yes, the information we're looking at is all in the past, but that doesn't mean it's not helpful. The way the stars, galaxies and universe act a billion years ago, are using the same physics they are using today. So if we can understand things that happening in the past, we're understanding how things are working today.