ASTR 1230 (O'Connell) Lecture Notes
THE MILKY WAY:
Our Galaxy from the Inside
The panoramic image above is a drawing constructed from photographs by
Knut Lundmark at the Lund Observatory in Sweden. It maps the
appearance of the entire sky (360 degrees) in Galactic
coordinates, in which the plane of our Galaxy defines the
equator. The picture is centered on the direction to the Galactic
center. The dark lanes or "rifts" are obscuration caused by dust
clouds lying in the plane.
You can identify a number of familiar features in the picture once you
get your bearings.
Compare the Lund drawing with this modern, color mosaic photograph
which is presented in the same format.
All of the above views are (obviously) from the Earth's perspective.
For a different perspective, click here for
a view (5000 light years wide) of the Sun's location in the Galaxy
together with identifications for a number of bright stars and other
features. This is part of the Richard Powell Atlas of the
Universe, a pictorial "zoomout" from the Solar System.
- Here is a labeled version of the panorama
with some important signposts marked.
- Sagittarius and Scorpio are in the center of the image, but their bright
stars are mostly hidden in the glow of the light of millions of fainter
stars in the plane.
- The brightest star in the image is Sirius, lying just below the plane
near the right hand edge of the image. Orion lies to the right and
below Sirius, tilted toward the right. You can see the three stars of
Orion's belt pointing at Sirius. Directly across (above) the plane
from the belt are Castor and Pollux, the two brightest stars in
- The part of the Milky Way that is visible in the summer sky runs from
the center to about 3/4 of the way to the left hand edge. Vega and its
constellation Lyra can be seen lying above the plane about halfway
from the center to the left hand edge. Cygnus is in the Milky Way,
just below and left of Lyra.
- The three stars at the extreme left hand edge of the image, just
above the plane, are in Auriga. The brightest is
Capella. This section of the Milky Way is visible in autumn
Click here for a wide angle picture
of the northern Milky Way with the bright constellations identified.
- The two cloudy patches below the plane and just right of center are the
Magellanic Clouds (only visible from the southern hemisphere). They are
external galaxies. M31, the bright galaxy in Andromeda, is visible as
a streaklike feature below the plane about 1/6 of the way from the left
March 2011 by rwo
Panoramic Milky Way image from Lund Observatory.
Northern Milky Way photo by J. Lodriguss. Text copyright ©
2000-2011 Robert W. O'Connell. All rights reserved. These notes are
intended for the private, noncommercial use of students enrolled in
Astronomy 1230 at the University of Virginia.