Daily Science Dump: The Milky Way Edition
Hola mis amigos! Today we will cover the most beautiful thing in our sky (arguably of course): The Milky Way! It’s Big, It’s Beautiful, so let’s just get right into it!
Our Place in the Milky Way
We know for sure that our solar system is located in a galaxy. Almost everybody knows that. But where exactly are we IN the galaxy? Thanks to astronomers before us, they’ve done the research and the math to estimate that we are about 2/3 the way in the Milky Way galaxy.
Let it be known, that we cannot know for sure exactly what our galaxy looks like. This is because none of our telescopes outside our solar system have gone outside the galaxy. Not even the Hubble Telescope has that capability. But we do know for sure that our galaxy is a spiral galaxy, and from observing behaviors of other spiral galaxies, we can make an educated guess as to what ours looks like. We also know that the galaxy is huge. So we can’t see everything in the Milky Way. What we can see looks a lot like this
We know that the Milky Way galaxy is a Spiral Galaxy. That much is known by us. What makes a spiral galaxy? Spiral galaxies, along with our own has 3 parts: bulge, disk, and halo. We all are most likely familiar with the disk because the disk gives the galaxy its distinct shape. That’s also where we are! The disk is about 1,000 light years thick and if you look at it edge on in looks like a cosmic pancake. This is where most of the young stars live because this is where most of the stellar nurseries are. The disk rotates around the bulge. The bulge signifies the center of the galaxy. This is where most of the older stars live. The bulge itself is somewhere along the lines of 10,000 light years across. Interestingly enough, at the center of our galaxy there is a black hole! Fortunately enough for us, the black hole won’t do any damage to us because we are about 28,000 light years from the center. Around the bulge and disk is the halo. The halo is mostly filled with globular clusters of stars, which are groups of a lot of stars together and looks like a big blob. The halo is where “dark matter” is. Dark matter, in a nutshell, is what is keeping the galaxies in tact.
A big question about how galaxies work is this: If stars form in the arms bands, how do they end up spreading all over the galaxy? And how do they get their spirals? Well, contrary to popular belief, the stars are not fixed structures! They actually do move. Now in all reality, a galaxy is just a big blob of stars. Like literally a big blob. The reason why they have spirals is because of something called the density wave. This just means that in some parts of the galaxy, there’s a larger concentration of stars.
So we know the Milky Way is a spiral galaxy. That’s almost a duh (almost). But what are some of the basic information of our galaxy? Like how old is the dang thing? How big is it? Well lemme tell you! The milky way galaxy is big. But it’s not the biggest. In length, our galaxy is about 100,000 lights years (the biggest galaxy is a whooping 522,000 light years across!). The age of the galaxy is astonishing! It has been narrowed to just after the Big Bang! Scientists believe our galaxy was form the moment galaxies could be formed. There are two methods of determining the age, both involving globular clusters. Globular clusters form when the galaxy forms. In the clusters, we can tell the age by red dwarfs or white dwarfs. Red dwarf stars are the best method because red dwarfs, unlike regular stars, can last for trillions of years. Knowing the age of red dwarfs can tell use the age of the cluster. Get the average age of a lot of clusters and you get the estimated age of the galaxy!
So that concludes this edition of Daily Science Dump! We learned how old and how big our galaxy is, what the components are, and where we are in the galaxy. Come back tomorrow for the first of three parts on Kepler’s Three Laws (they won’t be consecutive. That would be torture).
Also! Check out the NEW AND IMPROVED World of Astrophysics Official Tumblr page as well as the World of Astrophysics Official Instagram!