Author Topic: "How far can your telescope see?"  (Read 273 times)

tranardefa

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"How far can your telescope see?"
« on: December 27, 2017, 12:18:36 PM »
I get asked this a lot. The question comes in a few variations:

"You have a big telescope. It must be able to see very far."

"How far can your telescope see?"

"If I got a telescope, would it be able to see as far as yours?"I've not yet found a good, non-technical answer. How do you respond?



Kunjan Blanco

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Re: "How far can your telescope see?"
« Reply #1 on: January 04, 2018, 07:13:21 AM »
Just say, "It's not about how far I can see, it is rather how well I can see something that is far away." For instance, "You can see Saturn, right?", Then, so can I in my telescope . . I just see it better."

Cory Bass

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Re: "How far can your telescope see?"
« Reply #2 on: January 08, 2018, 06:57:40 AM »
Touche!

revenade

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Re: "How far can your telescope see?"
« Reply #3 on: January 09, 2018, 04:27:28 PM »
My scope can see up to infinity but unfortunately my eyes dont

Corey Howell

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Re: "How far can your telescope see?"
« Reply #4 on: January 09, 2018, 08:31:09 PM »
Why not give some examples of distances in LY to the targets of the night? To really dazzle them you can make a note or even memorize the distance in miles or AU .

"The Whirlpool galaxy is about 23 million LY distant. A light year is about 5.9 trillion miles, so the Whirlpool is about is about 23 million x 5.9 trillion miles."

If there is interest you can explain a light year.Those who care get something to think about and the rest can just agree when you say " a long way however you measure it"

omunsopoo

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Re: "How far can your telescope see?"
« Reply #5 on: January 10, 2018, 03:16:42 PM »
No real answer. Easiest option is to know the distances of a few galaxies, M31 is the easy one but get a general distance for the Virgo Cluster and maybe M81.

Point out that all the stars are "close" as they are part of our galaxy.

Most of the DSO's mentioned are sort of at maximum practical distance, better pont out that bigger scopes collect more light so more distant objects become apparent and also point out that images are collected and built up using cameras and a different process.

Mentioned M81 as there was a supernova in it a year or two back.

Matt Hodge

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Re: "How far can your telescope see?"
« Reply #6 on: January 11, 2018, 08:13:00 AM »
Quote
I get asked this a lot. The question comes in a few variations:

"You have a big telescope. It must be able to see very far."

"How far can your telescope see?"

"If I got a telescope, would it be able to see as far as yours?"I've not yet found a good, non-technical answer. How do you respond?

I got asked that a lot too....
I reckon it is a pre-conception came from the word "tele"scope in English and other languages similarly.
To the layman, the enlarged angular size relates to the distance conquered by the instrument. And the "tele" further suggest something magical with distance. For most, such pre-conception could have been formed in childhood.

So, my usual response would be like:
- it is a nice misunderstanding but a telescope has nothing to do with distance.
- telescopes are light collectorscoming indifferent sizes, thick ones and thin ones.
- telescopes are also 2D pattern magnifiers... what we see is always 2D... never 3-dimensional in fact.
- "infinity" is "how far" most lenses/scopes can be focused.

Well, frankly, I am never entirely happy with whatever the answer I can give..... the preconception has so deep roots that answers often confuse people more than clarify.

thesaroha

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Re: "How far can your telescope see?"
« Reply #7 on: January 12, 2018, 03:34:37 AM »
Quote
Quote

I get asked this a lot. The question comes in a few variations:

"You have a big telescope. It must be able to see very far."

"How far can your telescope see?"

"If I got a telescope, would it be able to see as far as yours?"I've not yet found a good, non-technical answer. How do you respond?

I got asked that a lot too....
I reckon it is a pre-conception came from the word "tele"scope in English and other languages similarly.
To the layman, the enlarged angular size relates to the distance conquered by the instrument. An the "tele" further suggest something magical with distance. For most, such pre-conception could have been formed in childhood.

So, my usual response would be like:
- it is a nice misunderstanding but a telescope has nothing to do with distance.
- telescopes are light collectorscoming indifferent sizes, thick ones and thin ones.
- telescopes are also 2D pattern magnifiers... what we see is always 2D... never 3-dimensional in fact.
- "infinity" is "how far" most lenses/scopes can be focused.

Well, frankly, I am never entirely happy with whatever the answer I can give..... the preconception has so deep roots that answers often confuse people more than clarify.

Actually, Telescopes do have a lot to do with distance. They are more than just light collections, they are primarily magnifiers, the increase the resolution as well. The effect of magnification is to bring objects closer. Magnifying an object 100 times gives it the same appearance as if were 100 times closer.

When someone asks me the question, I try to talk in specifics, the object in the eyepiece at the time, if I don't know it, I will look it up using Sky Safari. I will also use examples. Andromeda is visible naked eye, it's about 2 million light years. The most distant Messiers are generally thought to be about 60 million light years. Relatively small telescopes are capable of seeing messier galaxies. NGC 5350 can be seen with a 4 inch and is over 100 million lights distant. I generally say that galaxies that are hundreds of millions of light years can be seen. Quasars are the brightest objects in the universe, 3C 273 in Virgo can be seen in amateur telescopes and is estimated to be 2.4 billion light years...

Jon

galpaydabta

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Re: "How far can your telescope see?"
« Reply #8 on: January 12, 2018, 09:31:02 AM »
Quote
I get asked this a lot. The question comes in a few variations:

"You have a big telescope. It must be able to see very far."

"How far can your telescope see?"

"If I got a telescope, would it be able to see as far as yours?"I've not yet found a good, non-technical answer. How do you respond?

Between 1 Billion Light-Years to 12 Billion Light-Years depending...
a) Visually with a small aperture = about 1 Billion Light Years
b) Photographically with a large aperture = about 12 Billion Lights-Years

spicomgeovio

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Re: "How far can your telescope see?"
« Reply #9 on: January 12, 2018, 12:06:49 PM »
I don't figure most are asking for a technical answer, so I usually just say "All the way" or "How far do you want to see?"

laucongsnagal

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Re: "How far can your telescope see?"
« Reply #10 on: January 12, 2018, 07:44:47 PM »
Quote
I don't figure most are asking for a technical answer, so I usually just say "All the way" or "How far do you want to see?"


Yea. Any answer with numbers larger than 1000 or light years will glaze over the eyes of most.

bijstentetal

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Re: "How far can your telescope see?"
« Reply #11 on: January 12, 2018, 07:50:09 PM »
If I've got the time, and the individual seems to be responsive to a moderately complex answer, I'll 'splain what a light year is and how far away the 'stuff' in the sky really is. This occasionally leads into much of an evening's conversation. If I'm busy with setting up, or the asker doesn't seem to be actually interested (just asking something to impress the girl he's with), I just answer that I saw the light of a single exploding star about 12 million light years away a couple of years ago. The last one that got that answer was a kid who pulled into 'my' observing overlook and left the stereo thumping crude rap for several minutes, despite the presence of several families with kids in the overlook.

Jim H.

Anthony Eppinger

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Re: "How far can your telescope see?"
« Reply #12 on: January 14, 2018, 05:31:48 AM »
I have, on a number of occasions, seen the quasar 3C-273 with a four inch refractor; its distance being something over two billion light years.

Otto

hiswacoka

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Re: "How far can your telescope see?"
« Reply #13 on: January 18, 2018, 12:21:08 AM »
I would understand the question to the OP as "What is the most distant object you can see in your telescope?" and "Could my telescope see objects that far away?"

That should be answerable without too much techie detail. For most telescopes in dark skies it would be the most distant galaxy visible in the scope. You could point out that views of galaxies are very faint with low detail and no individual stars visible. For closer objects you can see more detail. Globular clusters would be next, located just outside the galactic disk, and for those you may see individual stars. You can work inward to objects in the Milky Way, and then inward to the planets and moon, with increasing detail visible at each step inward.

Then of course you could go into the time shift aspect, i.e. that galaxy is being seen as it was however many "light years" ago.

Jomega Ceo

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Re: "How far can your telescope see?"
« Reply #14 on: January 18, 2018, 08:20:49 AM »
Great discussion on what must be a commonly voiced question. Thanks, for everyone's input. Now, I think I can field that question, if I'm asked. Can anyone help with what might be the next question...How wide can your telescope see?
Grey