How do we see distant galaxies?

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In summary, the Hubble Space Telescope can see galaxies that are more distant and older than what we can see with our own eyes because it can see in forms of light that we can't see.
  • #1
Yosty22
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I understand that the Hubble Space Telescope is able to see these distant galaxies we discover, but how exactly does Hubble do that? I have heard the analogy that our galaxy and our place in it is like being in the middle of a forest. If we look any direction, we cannot see outside the forest because we are blocked by the very same forest. That is like we cannot see outside of our galaxy, because the light from our own galaxy is not allowing us to do that. Since the Hubble Space Telescope can see in forms of light outside the visible spectrum, is this why it is able to see "through" our galaxy to discover more distant and older ones?
 
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  • #2
Yosty22 said:
I understand that the Hubble Space Telescope is able to see these distant galaxies we discover, but how exactly does Hubble do that?

I'm not clear on why you think it is a problem.

I have heard the analogy that our galaxy and our place in it is like being in the middle of a forest. If we look any direction, we cannot see outside the forest because we are blocked by the very same forest.

Totally wrong analogy. We DO have trouble seeing THROUGH the Milky Way, but that's mostly in one direction (we're off to the edge). There is at least one galaxy that you can see with the naked eye, and more that you can see with amateur telescopes and the Hubble is WAY beyond being an amateur telescope.

That is like we cannot see outside of our galaxy, because the light from our own galaxy is not allowing us to do that.
Again, you have been misinformed.

Since the Hubble Space Telescope can see in forms of light outside the visible spectrum, is this why it is able to see "through" our galaxy to discover more distant and older ones?

That's how some telescopes do it but the Hubble does amazing things with just visible light. Google "Hubble Deep Field" for example.

Also, the Hubble is hardly the only telescope that studies far-off galaxies in the visible spectrum.
 
  • #3
Unfortunately, the term "smudge" is often associated with viewing distant galaxies.
Below is a Hubble shot of Ison with the caption including, "In general, redder things are older, more evolved, than blue things – this is true both for the crosshair-spiked stars and the smudges of distant galaxies."
http://hubblesite.org/hubble_discoveries/comet_ison/blogs/blog-exclusive-ison-in-space
 
  • #4
Yosty22 said:
I have heard the analogy that our galaxy and our place in it is like being in the middle of a forest. If we look any direction, we cannot see outside the forest because we are blocked by the very same forest. That is like we cannot see outside of our galaxy, because the light from our own galaxy is not allowing us to do that. Since the Hubble Space Telescope can see in forms of light outside the visible spectrum, is this why it is able to see "through" our galaxy to discover more distant and older ones?

Not really. To use your forest analogy, imagine the forest is on a totally flat plain and is very very sparse, but very very big. Looking UP you can easily see through the canopy because the trees are very very far apart. But, the closer your start to look towards the horizon, the more the trees block your view until eventually you cannot see through the forest.
 
  • #5
Drakkith said:
Not really. To use your forest analogy, imagine the forest is on a totally flat plain and is very very sparse, but very very big. Looking UP you can easily see through the canopy because the trees are very very far apart. But, the closer your start to look towards the horizon, the more the trees block your view until eventually you cannot see through the forest.

and to take that analogy a little further ... we are at the edge of the forest so looking in directions away from the centre of the forest ( Milky Way) we have an unobstructed view of most of the universeDave
 
  • #6
Try this one instead:

We're at the end of a long, straight highway lined with telephone poles. In any direction we look other than the one directly down the line of telephone poles, our vision is not obstructed. I believe this analogy is actually closer to the reality of the relative densities and angle of view obstruction.
 
  • #7
russ_watters said:
Try this one instead:

We're at the end of a long, straight highway lined with telephone poles. In any direction we look other than the one directly down the line of telephone poles, our vision is not obstructed. I believe this analogy is actually closer to the reality of the relative densities and angle of view obstruction.

Quit one upping everyone or I'm sicking Phinds on you!
 
  • #8
drakkith said:
quit one upping everyone or I'm sicking phinds on you!

arf !
 
  • #9
hopefully the OP got the understanding
unfortunately he/she never responded :(

Dave
 
  • #10
The good thing is that he doesn't need to. The multitude reading the post have also potentially learned something new whether the OP comes back or not. Stuff like this arms me with analogies to use when I too need to try and explain why some things are the way they are to the muggles in my life. Thanks guys.:smile:


Damo
 
  • #11
hi there Damo

no they don't, but its always nice when some one does to say "thanks for clearing that up" etc :)

Dave
 
  • #12
True, and it doesn't take much effort in forum etiquete to achieve this either. Damo
 
  • #13
Damo ET said:
True, and it doesn't take much effort in forum etiquete to achieve this either.


Damo

Yes, but it isn't really a matter of "form etiquette" so much as it is just a matter of simple every-day politeness, which some people don't have. You'll see that here from time to time. People just not answering questions that they are speciifically asked, or posting and then never responding.
 
  • #14
Well, I learned something from this thread, so thanks to the contributors. Now, it's my turn to nit-pick, because both of you are correct (Damo & phinds) ;)

When I type "define etiquette" into google, I get this.

et·i·quette
/ˈetikit/
Noun
The customary code of polite behavior in society or among members of a particular profession or group.
 
  • #15
travboat said:
Well, I learned something from this thread, so thanks to the contributors. Now, it's my turn to nit-pick, because both of you are correct (Damo & phinds) ;)

When I type "define etiquette" into google, I get this.

et·i·quette
/ˈetikit/
Noun
The customary code of polite behavior in society or among members of a particular profession or group.

Glad you learned something, and it's OK to point out that Damo is right, but PLEASE don't tell Drakkith he's right. It goes to his head and he gloats.
 
  • #16
phinds said:
Glad you learned something, and it's OK to point out that Damo is right, but PLEASE don't tell Drakkith he's right. It goes to his head and he gloats.

What's that I hear, Phinds? The snip snip of scissors at the vet?

I don't think we need a telescope to see where this is going. :tongue:
 

1. How do we know that distant galaxies exist?

We know that distant galaxies exist through observations made by telescopes and other instruments that are able to detect light and other electromagnetic radiation emitted by these galaxies. By analyzing the light and other data collected from these distant sources, scientists can gain insights into the existence and properties of these galaxies.

2. How do we see distant galaxies if they are so far away?

We are able to see distant galaxies through the use of powerful telescopes, such as the Hubble Space Telescope, which can capture and magnify light from these galaxies. The light from these galaxies travels through space and reaches our telescopes, allowing us to observe and study them.

3. What is redshift and how does it help us see distant galaxies?

Redshift is a phenomenon that occurs when the light from an object is shifted towards the red end of the electromagnetic spectrum. This happens when an object is moving away from us at high speeds. By measuring the amount of redshift in the light from a distant galaxy, scientists can determine its distance from us and gain insights into its properties.

4. How do we know that the light we see from distant galaxies is old?

The light we see from distant galaxies is old because it takes a long time for it to reach us. Due to the vast distances between us and these galaxies, it can take millions or even billions of years for their light to reach us. This means that the light we see from these galaxies is a snapshot of what they looked like in the past.

5. How do scientists study the properties of distant galaxies?

Scientists study the properties of distant galaxies through a variety of methods, including analyzing the light and other electromagnetic radiation emitted by these galaxies, measuring their redshift, and studying their structures and movements through computer simulations. They also use data from different types of telescopes and instruments to gather information about the composition, age, and other characteristics of these galaxies.

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