７ Solar System 【What is the Universe？】Dialogue with the Universe
○The Solar System is located in the Orion Arm, 26,000 light-years from the center of the Milky Way (100,000 light years in diameter).
○There are 200 billion stars in the Milky Way galaxy.
○The solar system is orbiting in the galaxy at a speed of 220km / s, for about one orbiting of the galaxy about 225-250 million years. 
○Revolution speed of the Earth is 30km per second.
○The brightness of the sun was only about 70% of the current in 4.6 billion years ago when the solar system was born, that has been increasing the brightness gradually thereafter.
○The sun continues to increase the brightness at a rate of 1% in about 100 million years now. 
Zooming out the Solar System 
○The earth revolves in Milky Way Galaxy while drawing a spiral.＜You Tube ＞
1. Wikipedia：Solar System
3. You Tube：The helical model - our Galaxy is a vortex