Let's travel to space - Galaxies - 01
Have you ever looked at the night sky and wondered about the blinking stars? Have you ever wondered what lies behind those dark night sky? In this short series, let us try to travel to space and explore Galaxies!
What is a Galaxy?
A galaxy is a large group of stars.
The word galaxy is derived from the Greek word "galaxias" which means "milky", a reference to our galaxy, Milky Way!
Milky Way galaxy:
The Milky Way is the galaxy that contains our Solar System. Its name "milky" is derived from its appearance as a dim glowing band curving across the night sky in which the naked eye cannot differentiate individual stars.
From the Earth, the Milky Way appears as a band because its disk-shaped structure is viewed from within the Galaxy.
Galileo Galilei first resolved the band of light into individual stars with his telescope in 1610.
Up until the early 1920s, most astronomers thought that all of the stars in the universe were contained inside of the Milky Way.
Debate between the astronomers Harlow Shapley and Heber Curtis and observations by Edwin Hubble in 1920, conclusively revealed that the Milky Way is just one of many billions of galaxies.
Yes there are many many galaxies in the space!
Shape of a galaxy:
No two galaxies are exactly the same but they do have various common shapes.
Galaxies fall into three basic shapes namely elliptical, spiral and irregular. The galaxies that do not fit into these basic shapes are called as peculiars.
Elliptical galaxies have an ellipse-shaped light profile.
Spiral galaxies are disk-shaped with dusty, curving arms.
Galaxies with irregular or unusual shapes are known as irregular galaxies.
The Milky Way galaxy is a barred spiral galaxy with approximately 100,000 - 120,000 light-years in diameter and contains 100 - 400 billion stars.
Light-Years
Space is very huge that distances are measured in light years.
Light year is the distance that light travels in a year which is 10 trillion KM!
The Solar System is located within the disk, about 27,000 light-years away from the rotational center of the Milky Way called as Galactic Center.
Size of a galaxy:
Based on size galaxies are categorized as,
Dwarf galaxies - Galaxies with as few as ten million stars
Average size galaxies - Our Milky way galaxy falls under the average size galaxy
Giant galaxies - Galaxies with one hundred trillion stars
Isn't it fantastic? Isn't the space so very interesting?
BTW, now we know, what's a galaxy, don't you?
We will meet again in two weeks! Stay tuned!