Our home: Milky Way galaxy

 

 One of my favourite ways to pass time has always been looking up at the sky and wondering how huge the universe is. When I was kid I lived in a small town so there were not much light pollution. Thus I could see the milky way band during clear nights. The band consists of stars which our eyes cannot differentiate and seems fuzzy. These stars extend over the horizon giving the appearance of a band. Above is one of the many beautiful pictures you can find in internet of the milky way band. It is one part of the galaxy we reside in. Today I want to talk a little about our home galaxy. 

 

An artistic illustration for our galaxy. http://apod.nasa.gov/apod/ap050825.html

 

 

 

 

Milky way galaxy is a barred spiral galaxy. You can see  artistic illustration  in the above picture. It is composed of spiral arms and a central bulge.The central bulge has a massive black hole. Since this bulge is very dense we cannot even see the centre of our galaxy. Thus, we cannot see the other side of the galaxy. Our galaxy contains about 200 billion stars and, it also contains lots of gas and dust to create billions of more stars. It has a diameter of 31 to 37 kpc. 1kpc is nearly equal to 3*10^16km which is a huge number.

The scale of size in astronomy is very interesting as well as frustrating at times. It is very difficult to comprehend the size scale in case of astronomical objects. I have linked a video which try to give you the idea of how huge the stars are. Thus might help you to understand the size scale.

http://www.youtube.com/watch?v=HEheh1BH34Q 

Also I am liking the blog by Brandon Kuschel where he has talked about the size of the universe. http://astrorad14.blogspot.com/2014/01/scale-of-universe.html

Our solar system is out of the central bar. Here is an illustration of the location of our solar system in the galaxy. Our solar system is revolving around the centre of the galaxy at the speed of 220 km/s.  

 Our sun is an average mass star and around 4.6 billion years old. About half of the stars in our galaxy are older than our sun. Most common stars are red dwarf in our galaxy. These are cooler and less massive than  the sun. The oldest star known in our galaxy is older than 13.6 billion year.

Even though our galaxy is huge, we are part of even bigger structure, called the cluster of galaxies. And we belong to Virgo cluster. And there are many such clusters. It is amazing how huge the universe is. 

Let's not stop looking at the vast and amazing night sky.