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Looking for ideas on how to reply to the "how far can you see" question...

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35 replies to this topic

#26 Neptunus Rex

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Posted 28 September 2023 - 01:13 PM

I usually start with the flash-bang issue. If it’s far away, when you see a flash, the bang comes later. (It relates to something they do understand.)

Then I tell them light is like sound, only much faster. It has finite speed.

The moon is two light seconds away. We see it two seconds in its past. Same with the Sun, only it’s eight minutes away. Then I move to the planets and then to whatever is in the eyepiece, usually a star. Then I pull up Stellarium and tell them how far that star is away (in time.).

Edited by Neptunus Rex, 28 September 2023 - 01:14 PM.

#27 astronz59


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Posted 28 September 2023 - 07:17 PM

You could try the analogy: "What you're looking at is so far away, that an ordinary rhinoceros running to it at a constant speed of 50mph and putting a dot on page every day would fill three warehouses with exercise books...lol.gif roflmao.gif

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#28 MarcF1701


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Posted 30 September 2023 - 01:35 PM

Last night I had fun sort of bending the minds of our attendees by telling them my scope, in this case the Tele Vue-76 was sort of like a "time machine" that sees into the past.  It was fun.  My demeanor was relaxed, voice soft, and lighthearted.  To see the faces of the kids light up with calling my scope that was priceless.  

I was getting sore in the back and legs after standing but I have to constantly tell myself not to stand with my arms across my chest as I look stand-offish, apparently anyway.

#29 joseluis.17g



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Posted 30 September 2023 - 09:03 PM

Whichever you decide to be your response a kindly starter to the answer would be "that’s a great question" I almost can guarantee that no matter your answer if you start your sentence with that, no one would feel bad 


and a great deal has to do with tone, we often forget how important our non verbal communication is 

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#30 Nankins


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Posted 03 October 2023 - 09:01 AM

Tell them how far away M31 is...  They'll get a kick that the naked eye can see that far!

#31 Nicole Sharp

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Posted 04 October 2023 - 12:49 AM

Hello all,

I love doing outreach & sidewalk astronomy. I love getting every type of question from people. I also try very hard to keep our astro techno-jargon out of my presentations, working hard to phrase things in terms that people can relate to & understand.

However, there is one question that still troubles me - "How far can you see with that scope?".

The problem for me is finding a reply that is not patronizing nor too involved so the person doesn't feel like they are being made to look like a moron nor to lose them in an explanation.

In preparing this post, a possible reply could be to say "a scope like this is designed to collect light, really faint light, which allows us to see not so much how far but how faint". Possible?

We all can come up with a flippant X light year reply, but this is a condescending thing to say first up, and certainly dismissive if that is all you says to a genuine question from people who don't know how to relate to an astronomical telescope. There in is the key issue, that people just have no way of relating to our gear that they really only see as "rocket science stuff" in no short way due to education, movies & media hype.

So, how have you answered this perennial question? Was/is your reply shaped by a context? Do you structure your reply to build upon an initial statement? Possibly your reply depends on the individual circumstance?


Quasar 3C 273 is typically the furthest object that can be seen in amateur telescopes.  There might be a couple of other quasars visible that are further away but I haven't tried for anything dimmer than 3C 273 yet.

Edited by Nicole Sharp, 04 October 2023 - 12:50 AM.

#32 Sebastian_Sajaroff


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Posted 08 October 2023 - 07:40 AM

"How far can you see with that telescope ?" is comparable to "How small can you see with that microscope ?". Those are not easy questions.

Best strategy : prepare yourself for that question and tell the truth according to your experience in the field.

Obviously, you'll have to read your observation log in advance to check what was the farthest object you ever observed.
Mine were M65/M66 in Leo, ~35,000,000 light-years away with an F/8 6" Newtonian during a Bortle 5-6 night (massive power outage at Montreal)

I know I can observe 3C273 (mag 12.9, 2440 million light-years away) from some Bortle 2 spot but never did it. So doesn't count for me.

Edited by Sebastian_Sajaroff, 08 October 2023 - 09:20 AM.

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#33 maroubra_boy



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Posted 09 October 2023 - 08:49 AM

In my original post I mentioned that just rattling off a stat is not the reason for either the question nor the best reply as this stat negates the entire purpose of a scope, to collect light, and the question is born out of ignorance from the person asking because they have no other way of relating to an astronomical scope.

Just rattling off X million light years is meaningless to someone with no understanding of either scopes or astronomy.

This is why Taosmath's reply (post No4) is exactly what I was after. It puts the purpose of an astronomical telescope in terms that the layperson can actually relate to.

There is a quasar within reach of my 17.5" dob that is 12 billion light years away - this sort of thing is meaningless. WE as astronomers put little significance to this sort of stat because our understanding of scopes is different, rather we consider how faint we can go, which with my 17.5" dob, a can see fainter objects than that distant quasar, which will also be much closer to us than that quasar.

Edited by maroubra_boy, 09 October 2023 - 04:13 PM.

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#34 StarAlert



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Posted 09 October 2023 - 09:46 AM

Well… in reality trying to comprehend the vastness of the universe is futile for even the smartest among us. I find it difficult to comprehend just how far away Proxima Centauri is, not to mention Andromeda. 

I explain to some of the more inquisitive passers-by that if North America represented the known universe, the entire contents of the universe would be represented by just three bees. If you’re one of these bees, what are the chances that you’ll ever make contact with one of the other two bees? Try and wrap your brain around that. 

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#35 DSOGabe


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Posted 12 October 2023 - 12:50 PM

I straight out tell them, X million light years out. I explain the challenges involved with that and it is also looking at the object as it appeared X million years ago. I am literally travelling back in time. 

#36 seasparky89


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Posted 09 November 2023 - 10:31 AM

I usually answer by explaining how the relative brightness of the object, the scope size and the seeing conditions all play a part.  I am reminded of a funny incident that happened right in my driveway.  During a neighborhood skywatch, my small scope was aimed at the moon.  A small child asked, “You can see all the way to the moon with that telescope?”  I replied, “you can see all the way to the moon without the telescope.”  He could not stop laughing, nor could his mom.



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