This first chapter contains all the contents learned on September and October 2021.

Into this chapter you will find the following contents:

• VLT's laser
• Types of spectrum
• Wien's law
• Stefan-Boltzmann's law
• Parallax
• Kepler's laws of planetary motion
• Brightness magnitudes
• Cepheid variable star
• Doppler spectroscopy method
• Binary stars
• Transit method

At the end of this chapter, there is a test which covers the contents seen over Chapter One. If you are a geek of astronomy click on Quiz and try answering the ten multiple-choice questions.