Why does the Andromeda galaxy appear so tiny from our perspective?

[russ_watters]

Andromeda would be synonymous with the Moon, Venus, Jupiter, Sirius, etc.

Synonomous in what way?

 

[Dnj23]

Synonomous in what way?

In terms of significant brightness to make it noticeable.

 

[Dnj23]

I'm done with this thread.

 

[pinball1970]

I'm done with this thread.

It's your thread! You've had some great stuff/images/explanations!

 

[Zeke137]

I think it might be helpful at this stage to point out how telescopes actually make the beautiful bright images of deep-sky objects like the Andromeda Galaxy, or the Orion Nebula, or the Crab Nebula, to name but a few:

These objects are pretty faint (they're a long way away), so the amount of light received by a telescope from such an object in anyone instant is simply not sufficient to capture a decent image. The same goes for the naked eye, which can only see the brightest parts (relatively speaking) of such objects and hence why it's so difficult to see them with the naked eye.

Even looking through a large telescope with the naked eye, the objects still appear pretty faint. I myself have vivid memories of viewing Halley's Comet on several occasions over a period of few weeks back in 1986 through a 1-meter Cassegrain reflector and being disappointed at how very faint it appeared through the eyepiece.

So, a quick snapshot of such an object as taken by a telescope, or even by a simple camera pointed at the sky, will only register a faint image of the object, and almost none of the fine filigree detail and colors as seen in pictures like those above would appear in the snapshot. It usually takes at least a few minutes, and as much as several hours of the telescope being pointed at the object, and following it precisely as it moves across the sky, in order to gather enough light in the photographic plate or CCD sensor to arrive at the splendid and colourful images we are lucky to see these days.

Let's imagine that we have at our disposal a particular telescope, which will take six minutes to capture enough light to produce a good image of the Andromeda Galaxy. The sensor would register something very like each of the following images at the end of each 1-minute interval during the exposure:

after 1 minute

after 2 minutes

after 3 minutes

after 4 minutes

after 5 minutes

at the end of the full exposure​

It's only after the full period of the exposure (six minutes in our example here) that the full extent of the galaxy is visible. It takes that long for our telescope to gather enough light to be able to discern the finest details of the galaxy at its' furthest extents.

Again, I hope this helps to explain why images taken by powerful telescopes of extended objects in the sky like galaxies and nebulae look nothing like how they would appear to the naked eye.

(Image: By Adam Evans - M31, the Andromeda Galaxy (now with h-alpha)Uploaded by NotFromUtrecht, CC BY 2.0, https://commons.wikimedia.org/w/index.php?curid=12654493)

 

[pinball1970]

I think it might be helpful at this stage to point out how telescopes actually make the beautiful bright images of deep-sky objects like the Andromeda Galaxy, or the Orion Nebula, or the Crab Nebula, to name but a few:

View attachment 251165​

These objects are pretty faint (they're a long way away), so the amount of light received by a telescope from such an object in anyone instant is simply not sufficient to capture a decent image. The same goes for the naked eye, which can only see the brightest parts (relatively speaking) of such objects and hence why it's so difficult to see them with the naked eye.

Even looking through a large telescope with the naked eye, the objects still appear pretty faint. I myself have vivid memories of viewing Halley's Comet on several occasions over a period of few weeks back in 1986 through a 1-meter Cassegrain reflector and being disappointed at how very faint it appeared through the eyepiece.

So, a quick snapshot of such an object as taken by a telescope, or even by a simple camera pointed at the sky, will only register a faint image of the object, and almost none of the fine filigree detail and colors as seen in pictures like those above would appear in the snapshot. It usually takes at least a few minutes, and as much as several hours of the telescope being pointed at the object, and following it precisely as it moves across the sky, in order to gather enough light in the photographic plate or CCD sensor to arrive at the splendid and clourful images we are lucky to see these days.

Let's imagine that we have at our disposal a particular telescope, which will take six minutes to capture enough light to produce a good image of the Andromeda Galaxy. The sensor would register something very like each of the following images at the end of each 1-minute interval during the exposure:

View attachment 251167
after 1 minute

View attachment 251168
after 2 minutes

View attachment 251169
after 3 minutes

View attachment 251170
after 4 minutes

View attachment 251171
after 5 minutes

View attachment 251172
at the end of the full six-minute exposure​

It's only after the full period of the exposure (six minutes in our example here) that the full extent of the galaxy is visible. It takes that long for our telescope to gather enough light to be able to discern the finest details of the galaxy.

Again, I hope this helps to explain why images of extended objects in the sky like galaxies and nebulae look nothing like how they would appear to the naked eye.

Amazing set of images.

 

[Zeke137]

I'm done with this thread.

Too many facts and too little fake news for your taste?

 

[Dnj23]

Let's just say that the image I posted above shows rather well the relative sizes of Andromeda and the Moon on the sky, and has a nice tree in the foreground as a further aid to visualizing relative sizes. And that the central portion of Andromeda as viewed with the naked eye is just about the size on the sky as portrayed in the picture.

Let's just say.

 

[Zeke137]

Let's just say.

You started this thread, and people came into try and help out. Plenty of people here, some of whom are practising scientists, and others who have university degrees in relevant scientific areas, have tried to help you out here.

But it would appear that you are not at all prepared to accept the help that you have been given. That's OK, that's your call, but I'm wondering why on Earth you bothered to ask the question "Where am I going wrong with this?" in the first place, and why you've persisted in rejecting help.

Well, you'll get no more help from me. Good luck with your obstinately dismissive attitude.

 

[Dnj23]

I don't understand your question. First, do you understand that the moon in the image @Zeke137 posted is there to give you a sense of scale, not brightness? The actual moon would be far, far brighter. Having said that, everything in his image is much dimmer than your "top 10" list.

I don't understand your response.

"So, here's another picture which shows the Andromeda galaxy as it would appear to the naked eye in a not very dark sky -"

 

[Dnj23]

You started this thread, and people came into try and help out. Plenty of people here, some of whom are practising scientists, and others who have university degrees in relevant scientific areas, have tried to help you out here.

But it would appear that you are not at all prepared to accept the help that you have been given. That's OK, that's your call, but I'm wondering why on Earth you bothered to ask the question "Where am I going wrong with this?" in the first place, and why you've persisted in rejecting help.

Well, you'll get no more help from me. Good luck with your obstinately dismissive attitude.

If anyone had a nice tree in the foreground near sunset, they aren't looking at anything what I'm mentioning.

 

[fresh_42]

If anyone had a nice tree in the foreground near sunset, they aren't looking at anything what I'm mentioning.

Before we end up with the birds and the bees, and since the question has been answered in all detail, it's time to close the discussion.

Thank you for participating.