# Telescopes and light years

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#### cryptical

##### Guest
My question of the day is this;<br /><br />Regarding Light Years:<br /><br />Let's say that we observe a distant star with the naked eye. Then we look at this star with a telescope. When people claim that a star is XX light years away, are they claiming that information by the naked eye, or a telescope? <br /><br />I mean, if Hubble is looking 100 million light years away, depending on its maginification, what is the true distance of the object? How far can a commercial type telescope penetrate the sky? If a star is 100 million years away with the naked eye, then would you say, that with the Hubble, it may only be 25 million? So, if we us the Hubble to to see the out-reaches of the universe, 50+ billion light years away, would not the universe be older, since we are maginifiying the caputured light?? That light has not hit Earth yet.

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#### MeteorWayne

##### Guest
Welcome to SDC!!<br /><br />Since light travels with a fixed speed, no matter what device you use, the light is the same distance and time away.<br /><br />A telescope lets you see fainter objects than you can observe with the naked eye, so you can see further back in time. But looking at the same object, the time and distance are the same.<br /><br />By the way, do you know that you can see something 2.9 million light years away with the naked eye?<br /><br /> <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

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#### cryptical

##### Guest
What you are saying, even with the hHubble, is that the data is in present time, and Hubble is not taking off 200 million light years of the travelled light of a distant star, because of the distance it covers?

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#### MeteorWayne

##### Guest
Hubble doesn't change the speed of light, so if something is 200 million light years away, we are looking at light emitted 200 million years ago, 200 million light years distant. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

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#### cryptical

##### Guest
Yes, but we are maginifying. Even with binoculars, objects appear to much closer then they are. Lets take the sun for instance- it takes about 8 minutes for the light to reach earth, through a telescope, are you still saying that the solar flares that can be seen are still 8 minutes old ? Not 4 mintues old?

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#### MeteorWayne

##### Guest
No matter what the light still takes 8 minutes (actually, today 8 minutes, 10.9 seconds).<br /><br />Telescopes collect more photons, and can make the image bigger, but can't change the speed of light. <br />Making the image bigger doesn't change the speed of light. So when you look up and see the sun in the sky, or through a properly filtered telescope, you are still looking at where it was over 8 minutes ago.<br /><br />And if you look up at Saturn tonight, you are actually looking at where it was 69.1 minutes ago, whether with your eye or a telescope. <br /><br />How big you make it doesn't change how long it takes the light to get here. It still travels 186,000 mph. <div class="Discussion_UserSignature"> <p><font color="#000080"><em><font color="#000000">But the Krell forgot one thing John. Monsters. Monsters from the Id.</font></em> </font></p><p><font color="#000080">I really, really, really, really miss the "first unread post" function</font><font color="#000080"> </font></p> </div>

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#### docm

##### Guest
Distances to many objects can be measured using the parallax effect;<br /><br />http://www.eg.bucknell.edu/physics/astronomy/astr101/specials/parallax.html <br /><br />For objects very far away where angular measurements are iffy, like clusters or galaxies, a star in them that is of known brightness can be used; typically what is known as a Cepheid variable whose correlation between their period of variability and absolute brightness can be used to calculate their approximate distance. <div class="Discussion_UserSignature"> </div>

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#### weeman

##### Guest
Cryptical, the device that you're using makes no difference, whether it be the naked eye or the most powerful telescope on Earth. The light from the Sun still has to travel the same distance to reach a ground based telescope as it does to reach your eyes. If I am looking at a galaxy that is several million lightyears away, it will look bigger and brighter through my telescope, but my telescope isn't any closer to the object than my own eyes. So, even if your telescope magnifies the Sun's solar flares, it still takes the light 8 minutes to reach your telescope. <br /><br />I can however kind of understand your dilemma. <div class="Discussion_UserSignature"> <p> </p><p><strong><font color="#ff0000">Techies: We do it in the dark. </font></strong></p><p><font color="#0000ff"><strong>"Put your hand on a stove for a minute and it seems like an hour. Sit with that special girl for an hour and it seems like a minute. That's relativity.</strong><strong>" -Albert Einstein </strong></font></p> </div>

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