When I look at the Milky Way, what am I looking at?

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Discussion Overview

The discussion revolves around the question of what one sees when looking at the Milky Way galaxy, specifically whether observers are viewing another arm of the galaxy or looking towards its center. The scope includes observational astronomy and conceptual understanding of galactic structure.

Discussion Character

  • Exploratory
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant asks whether looking at the Milky Way means seeing another arm of the galaxy or the center.
  • Another participant notes that the farthest visible stars are about 4,000 light years away, while the Milky Way is 100,000 light years across, suggesting limited visibility of the galaxy's structure.
  • Some participants propose that when looking at the Milky Way's white band, one is likely looking towards the center, particularly in the direction of the constellation Sagittarius.
  • It is mentioned that the visibility of the galactic core is obstructed by dust and gas, which prevents seeing it in visible light, but it can be observed through other wavelengths like infrared and X-rays.
  • One participant clarifies that the band of the Milky Way surrounds the observer, complicating the notion of a singular "center," but acknowledges that the brightest part of the Milky Way corresponds to the direction of Sagittarius.
  • There is a discussion about the visibility of other galaxies, with some participants correcting earlier claims about what can be seen with the naked eye.

Areas of Agreement / Disagreement

Participants express varying views on whether looking at the Milky Way equates to looking towards its center, with some agreeing on the direction towards Sagittarius while others emphasize the complexity of the galaxy's structure. The discussion remains unresolved regarding the specifics of visibility and perception of the galactic core.

Contextual Notes

Participants note limitations in visibility due to intervening dust and gas, and there are unresolved questions about the exact nature of what is seen when observing the Milky Way.

kmm
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More specifically, when I look at the milky way am I seeing another arm of the galaxy or am I looking towards the center of the galaxy? I'm having a hard time finding a specific answer to this question. Thanks!
 
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Well, the farthest away star visible to the naked eye is about 4,000 light years away but the milky way is 100,000 light years across and we are something like 1/3rd of the way from the edge towards the center, so you're not seeing much of it.

A few of the things you see are galaxies that are as much as 2 to 3 million light years away, but they are so small that they look like stars, I'm pretty sure.
 
Thanks! Ok so I won't actually see the center of the galaxy, but are you saying that I actually am I looking towards the center of the galaxy?
 
phy_infinite said:
Thanks! Ok so I won't actually see the center of the galaxy, but are you saying that I actually am I looking towards the center of the galaxy?

I THINK, but don't know for sure, that yes we are looking towards the center when we look at the center of the white band that is the Milky Way as we see it. You definitely can't see anywhere near as far as the center without a telescope.

Some of our astronomers can likely provide a more solid answer, so I hope one of them will jump in here.
 
phy_infinite said:
...when I look at the milky way am I seeing another arm of the galaxy or am I looking towards the center of the galaxy? I'm having a hard time finding a specific answer to this question. Thanks!

It depends on which part of the Milky Way you are observing. In the direction of Sagittarius lies the galactic center. If you were viewing the constellations of Taurus/Auriga, you would be looking in the opposite direction towards the edge of the galaxy.

Try using this map to orient yourself:
http://maps.nationalgeographic.com/maps/print-collection/milky-way.html
 
Jimmy said:
It depends on which part of the Milky Way you are observing. In the direction of Sagittarius lies the galactic center. If you were viewing the constellations of Taurus/Auriga, you would be looking in the opposite direction towards the edge of the galaxy.

Try using this map to orient yourself:
http://maps.nationalgeographic.com/maps/print-collection/milky-way.html

I'm referring to what phinds said. As he said, "..when we look at the center of the white band that is the Milky Way as we see it." In that case am I looking towards the center?
 
Jimmy said:
It depends on which part of the Milky Way you are observing. In the direction of Sagittarius lies the galactic center. If you were viewing the constellations of Taurus/Auriga, you would be looking in the opposite direction towards the edge of the galaxy.

...

Yes correct

phy_infinite

the thing that stops us seeing the core of our galaxy isn't the distance, its all the dust and gas
that is between us and it.
We observe the core by the infrared light, gamma rays and X-rays that are emitted from it
we cannot see the visible light because of the intervening dust etc

Dave
 
davenn said:
phy_infinite

the thing that stops us seeing the core of our galaxy isn't the distance, its all the dust and gas
that is between us and it.
We observe the core by the infrared light, gamma rays and X-rays that are emitted from it
we cannot see the visible light because of the intervening dust etc

Dave

I understand why I can't see the core of our galaxy. I only want to know that when I look at the center of the white band in the sky, whether or not I am looking in the direction of the core of the galaxy.
 
The center of the galaxy is in the direction of the constellation Sagittarius.
 
  • #10
phy_infinite said:
I only want to know that when I look at the center of the white band in the sky, whether or not I am looking in the direction of the core of the galaxy.

The band of the Milky Way surrounds us so there really isn't a center in that sense. In the summer—for the northern hemisphere—the galactic center can be seen* in the direction of Sagittarius. It will be the brightest part of the MW. In the winter, the sun obscures our view of the center but you can still see the faint glow of the spiral arms away from the center if you are at a dark site.

Winter MW left, Summer MW right:
http://twanight.org/newTWAN/photos/3001899.jpg

* The galactic center can't really be seen visually due to the intervening gas and dust, as davenn pointed out in post #7. I simply mean that that is the direction in which the center lies.
 
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  • #11
Cool! Thanks for the clarification Jimmy!
 
  • #12
phinds said:
A few of the things you see are galaxies that are as much as 2 to 3 million light years away, but they are so small that they look like stars, I'm pretty sure.

Any galaxy that is small enough to be star sized is much too dim to be seen by the naked eye. The Small and Large Magellenic Clouds (close dwarf galaxies visible from the souther hemisphere) and the Andromeda galaxy is visible as patches of dim light from a dark site and the Triangelum Galaxy is visible from a very dark site if you have good enough eyes. If you count Omega Centauri as a dwarf galaxy that one is very easy from a darkish site (also an southern object and almost star sized). On top of that there is a couple of galaxies that might just about be possible if you have extremely good eyes and skies.

More info on wikipedia
 
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  • #13
glappkaeft said:
Any galaxy that is small enough to be star sized is much too dim to be seen by the naked eye.

OK, my "pretty sure" was wrong. Thanks for that correction.
 

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