# Homework Help: Telescope to see stars

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1. Mar 31, 2012

### Emilyjoint

1. The problem statement, all variables and given/known data
Vague class discussion. Stars are points and a telescope does not magnify them.
How then can more stars be seen with a telescope?

2. Relevant equations
I know magnification for a telescope is fo/fe but that is not much help
3. The attempt at a solution
Is it because diffraction makes bigger images?

2. Mar 31, 2012

### turbo

Here's a hint. How does a telescope differ significantly from your naked eye?

3. Mar 31, 2012

### Emilyjoint

The main thing about a telescope is that it magnifies.
That is what I think fo/ fe means

4. Mar 31, 2012

### turbo

You are missing an important quality of telescopes.

5. Mar 31, 2012

### Emilyjoint

I know that they cause diffraction which makes point sources larger. Is that what you mean.
Ps... I have looked on wiki for telescope magnification and could not find an explanation

Last edited: Mar 31, 2012
6. Mar 31, 2012

### turbo

Nope. You're over-thinking this. Go to the "telescope" thread and see if you can figure it out. I can't give you the answer (forum roles), but I can show you the way to good resources.

7. Mar 31, 2012

### Emilyjoint

I have just spent half an hour or so looking through that reference. It gives lots of advice about which telescope to buy.....I already own a telescope (Meade)....but there is nothing to help me explain how I can see more stars !!!!
"I am missing an important quality of telescopes"......"I am over-thinking this"..... I dont get it.... is there a straight forward answer ?
Do you have any other references that might help.
Is my diffraction idea wrong?

8. Mar 31, 2012

### turbo

What are the critical physical qualities of the telescopes in that thread?

9. Mar 31, 2012

### Emilyjoint

??????

10. Mar 31, 2012

### turbo

11. Mar 31, 2012

### Emilyjoint

I am no wiser about how it is that more stars can be seen through a telescope.
My first and only idea was that diffraction make bigger images and I will stick with that in our class discussion.

12. Mar 31, 2012

### turbo

Don't do that emily, because it is wrong. Which telescopes will show you more stars than others and why?

13. Mar 31, 2012

### Emilyjoint

I think I am correct when I say that diffraction makes stars look bigger. We have done calculations to show what is meant by 'resolution' which is to do with separating images.
I also know the equation for calculating angular width to find the size of a point source.
I do not know how it is wrong that this explains how stars can be seen !!!!
If they look bigger because of diffraction it sounds right to me.

14. Mar 31, 2012

### turbo

Again, what qualities would you want in a telescope to show you more and more (fainter and fainter) stars?

15. Mar 31, 2012

### Emilyjoint

they should have bigger diffraction patterns.... I dont know.... that is why I came here.... for help.

16. Mar 31, 2012

### turbo

That's not the answer. I'm trying to throw resources at you, but I can't simply give you the answer. Forum rules, sorry.

17. Mar 31, 2012

### Emilyjoint

But am I correct in saying that the diffraction pattern will be larger ?
If so I can use that in my discussion, something will come of it
I do not understand your 'rules'

18. Mar 31, 2012

### turbo

Do you think huge professional telescopes have large diffraction patterns, and that's why they can show more stars?

19. Mar 31, 2012

### Emilyjoint

you tell me !!!! It sounds reasonable to me !!!!...if it works

Last edited: Mar 31, 2012
20. Mar 31, 2012

### Jimmy Snyder

Emily, you already know that the telescope doesn't make the star larger. What else does a telescope do. Something that's different from what your eyes do.

21. Mar 31, 2012

### Staff: Mentor

We don't give out answers here. We will guide you, but you have to do the work.

22. Mar 31, 2012

### Emilyjoint

I am lost !!!! I think that the telescope does make the image of the star larger....isn't that what the diffraction pattern is.
That is the only thing that I can think of that makes it possible to see more stars.
I know that I have to do the work......I realise that no one here is going to give me an answer..... I do not need to be told that !!!! is this a physics forum ?????

23. Mar 31, 2012

### Emilyjoint

no one has been able to give a better explanation than mine..... am I wrong?????

24. Mar 31, 2012

### micromass

Why is it better to have large telescopes??

25. Mar 31, 2012

### Jimmy Snyder

Emily, is there a book to go with your class? If so, does it have a discussion on how a telescope works? It does not make stars appear larger. At least let that soak in.