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When I look up in the night sky, I assume the brightest area, commonly known as "The Milky Way", is the Galactic Center of our home galaxy.

The Milky Way

But then I stumbled upon this illustration, which seems to suggest what I'm seeing is (and by far) not the Galactic Center. In fact, from this picture it looks like the brightest area might be the closest spiral arm (on the opposite direction of the galactic center).

what can be seen in our night sky

I know this illustration is not meant to be precise, so it's probably not the closest spiral arm either.

So, what am I really looking at when I stare at the brightest spot of the night sky? What percentage of it would be stars, planets, and nebulae? And what's the farthest object I can see in that direction with my unaided eyes?

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  • $\begingroup$ "What is in the brightest area of the night sky?" -- A full moon? 8-)} $\endgroup$ – Keith Thompson Oct 27 '15 at 20:55
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All quoted text in this answer is from image captions in the Wikipedia article on the Milky Way.

360-degree panorama view of the Milky Way (an assembled mosaic of photographs) by ESO

From ESO

This magnificent 360-degree panoramic image, covering the entire southern and northern celestial sphere, reveals the cosmic landscape that surrounds our tiny blue planet. This gorgeous starscape serves as the first of three extremely high-resolution images featured in the GigaGalaxy Zoom project, launched by ESO within the framework of the International Year of Astronomy 2009 (IYA2009). The plane of our Milky Way Galaxy, which we see edge-on from our perspective on Earth, cuts a luminous swath across the image. The projection used in GigaGalaxy Zoom place the viewer in front of our Galaxy with the Galactic Plane running horizontally through the image — almost as if we were looking at the Milky Way from the outside. From this vantage point, the general components of our spiral galaxy come clearly into view, including its disc, marbled with both dark and glowing nebulae, which harbours bright, young stars, as well as the Galaxy’s central bulge and its satellite galaxies. As filming extended over several months, objects from the Solar System came and went through the star fields, with bright planets such as Venus and Jupiter. For copyright reasons, we cannot provide here the full 800-million-pixel original image, which can be requested from Serge Brunier. The high resolution image provided here contains 18 million pixels.


Here is a schematic map of our POV in the Milky Way galaxy.

Observed (normal lines) and extrapolated (dotted lines) structure of the spiral arms. The gray lines radiating from the Sun's position (upper center) list the three-letter abbreviations of the corresponding constellations.

From Wikipedia

A "God's view" map of Milky Way as seen from far Galactic North (in Coma Berenices). The star-like lines center in a yellow dot representing the position of Sun. The spokes of that "star" are marked with constellation abbreviations, "Cas" for "Cassiopeia", etc. The spiral arms are colored differently in order to highlight what structure belongs to which arm. H II regions are marked as dots colored in the same color as their spiral arm. They come in three sizes, measured by the excitation parameter U: small - U > 200 pc cm-2 medium - 200 > U > 110 pc cm-2 large - 110 > U > 70 pc cm-2


It turns out we are in an arm -- the Orion-Cygnus Arm. The much brighter part of the Milky Way from our POV is in the direction of the galactic center, but the actual nucleus around the supermassive black hole is obscured by dust. If it was visible, it would be quite bright. What we are seeing that is bright is mostly the pseudobulge, or galactic bar formation, in the middle of the galaxy. We are looking at the galactic bar almost end-on, so it resembles a sphere from our POV.

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  • $\begingroup$ Thanks a lot for your time! Is the POV map, especially the observed lines (not the dotted ones) an accurate representation of what's visible to the naked eye, or is the map emphasizing on what's possible to the telescope and thus has little to do with the bright spot in the dark sky? If we can in fact see the galactic center, would you say my linked illustration is misleading? $\endgroup$ – user1032613 Oct 26 '15 at 21:25
  • $\begingroup$ @user1032613 technically, we do not see the very center, but parts (amounting to about half?) of the bar-shaped bulge. Yes, that image is misleading in several ways. Our galaxy has more arms and they are more tightly wound than in that picture. We are further out than in the illustration. And we are much more lined up with the bar in the center. $\endgroup$ – Aabaakawad Oct 26 '15 at 21:42
  • $\begingroup$ @user1032613 it is schematic, but the solid parts of the colored arms are observable in visible. The dashed parts of the arms are from longer-wavelength observations. $\endgroup$ – Aabaakawad Oct 26 '15 at 21:47

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