Our Solar System is just one within our Milky Way galaxy. It’s called the Milky Way because of the glowing band that we see in the night sky that appears to look like a pale stream of milk.
|Radius:||52,850 light years|
|Distance to Galactic Centre:||27,000 light years|
|Mass:||800 - 1,500 M☉|
|Age:||13.6 Billion years|
|Number of Stars||250 billion ± 150 billion|
The Milky Way arches across the sky and while each star is another Solar System, we can’t distinguish the individual stars.
Our ancient ancestors looked to the night sky to see the Milky Way and believed that this was part of their idea of “heaven.” Astronomers know that we are really viewing the center of the galaxy as our Solar System exists in one of the galaxy’s outer arms.
Due to the density of the Milky Way, it’s almost impossible to see to the other side.
The Milky Way is one of the spiral galaxies and they are the most common. Two thirds of the galaxies in the universe are spiral galaxies.
Our spiral galaxy is called a barred spiral, and has a bar across the middle region and two major “arms” and two smaller “spurs.” One of the spurs in the Milky Way galaxy is named the Orion Arm and this is where our Sun and Solar System is located.
Two other major arms are around the Orion Arm, and are called Sagittarius and Perseus.
Our Solar System and the Milky Way galaxy is constantly rotating and moving through space. The Sun and Solar System travel along with the Milky Way galaxy.
Our Solar System is moving at an average speed of 515,000 mph/828,000 km/h.
While this sounds like an almost incredibly fast speed, it still takes our Solar System 230 million years to make the trop all the way around our Milky Way galaxy.
Stars and gas crowd more closely together as you near the center of a galaxy. Spiral arms in a galaxy have been compared to traffic jams, as they move more slowly.
The one thing that is important to note is that as space material crosses the dense spiral arm path it is compressed and believed to then act as a trigger to create more stars.
The Milky Way galaxy is surrounded by a huge hot gas halo that extends out for hundreds of thousands of light years. It’s thought that this gas halo is as large as all of the stars that are contained in the Milky Way.
The halo is spinning rapidly, along with the galaxy and while it has its own rotation, it is slower than the rest of the galaxy disk.
The center of our galaxy contains what is called the “galactic bulge.” This area is jam packed with dust, stars, and gas, and is the heart of the galaxy.
The density of the bulge is what keeps us from being able to see more details and to the other side of the galaxy.