1. Astronomy

2. I. Early Astronomers  Ptolemy: (140 yr)  A Greek astronomer theorized the model of the universe. The Ptolemaic theory suggested that the Earth was the center of the Universe. Ptolemy’s theory was popular for over 1,500 years in Europe.

3. Copernicus: (1543 yr)  A Polish astronomer revolutionized astronomy with his new model of the universe. He theorized that the Sun was the center of the universe and all the planets including Earth orbited around it.

4. II. E LECTROMAGNETIC S PECTRUM Electromagnetic spectrum is made up of all the wavelengths of electromagnetic radiation. (ex. X-rays, radio-waves)

5. Telescopes are instruments that are used to observe electromagnetic radiation from space. Refraction – when light bends because it is passing through mediums of different densities. Reflection – when light bounces off a surface.

6. III. S TARS Composition (make up) of stars: Stars are made up of different elements in the form of gases. (ex. Hydrogen) Scientists classify stars by: Color Temperature Brightness or Magnitude