Illustration of what this area looks like from up in Mayhill NM. Reproduced from the application Stellarium to recreate as closely as possible what is seen with the naked eye. The edge on view of our galaxy’s core extends from the bottom of the teapot in Saggitarius and extends all the way past Antares which is a great landmark visually. Antares is in the constellation Scorpius . That constellation always reminds me of a lawn chair. Antares is at the foot of the chair. “CB” or the Central Bulge as it is referred to in drawings is at the head of the chair.
As we get closer to summer, the most glorious region of the night sky as seen from the Northern Hemisphere becomes visible and that is the southern portion of the Milky Way. Looking south now about 2-3 am what you see is illustrated above. It is important to note that when we do this we are looking toward the center of our own galaxy from one of the outer arms. A favorite activity of mine is binocular observing in this region. You could spend weeks doing that!
Just above Antares is one of the most colorful regions of the Milky Way band. The Rho Ophiuchi cloud complex is a dark nebula of gas and dust that is located 1° south of the star ρ Ophiuchi of the constellation Ophiuchus, just above Saggitarius. It is one of the closest star-forming regions to the Solar System, about 360 light years away. This wonderful wide field image was captured by Rick Young, who has an observatory not far from mine and does a lot of nightscape photography as well
On to “our place in the universe”!
Our Milky Way galaxy, the one we live in, is a spiral galaxy measuring about 120,000 light years in diameter and contains about 200 billion stars! The galaxy is a disc, so you can imagine living inside of a dinner plate and we are kind of on the outer rim of the plate. Earth is actually about 27,000 light years from the center (1 light year = 6 trillion miles). So imagine you are inside of the plate. If you look either upward or downward you would be looking out of the plate, away from it, where it would be much less dense and as a result you are going to see less stars. Now if you try to look from inside the plate toward the center of plate you are looking into a region of high density and you are going to see more stars as well as a lot of dust contained within the galaxy’s disc. This is why we are seeing what we see when we look through the disc or “band” of the Milky Way.
We are inside of this plate looking along the plane of the disc and this is why we see the Milky Way as we do
Southern Milky Way band on a clear summer night. We are looking through the plane of the galaxy’s disc just like being inside of the plate above!
On a final note, it was only close to 100 years ago that the astronomer Edwin Hubble first determined that our Milky Way galaxy was not the only galaxy in the universe! Of course now we know it’s only one of billions! See this fascinating APOD (Astronomy Picture of the Day) entry for more on Hubble’s discovery. Make sure to look at the April 26, 2020 entry. The link above will only take you to that days’ image whatever day you are looking at it so you will have to go to the archive page to find it if you are doing this after April 26.
Mount Wilson Observatory in Pasadena CA was home to the largest telescope in the world from 1917 until 1949. The Hooker 100″ reflector owned that title until the 200″ telescope at Mt Palomar was completed. During the early part of the 20th century many of the world-renowned scientists and astronomers went to Mt Wilson to conduct research there. Einstein, Hubble and several others were all there. This is where Hubble figured out our galaxy was not alone!
In the summer of 2003, I had the good fortune to be able to spend 2 weeks at Mt Wilson where I did a spectroscopy project. In the basement of the observatory housing the Hooker 100″ telescope were the lockers of the scientists but it was very dark when I tried to take this picture of Edwin Hubble’s locker!
Thanks for reading!
DrDave
daveandtelescope 