Studying space from Earth

1. Studying space from Earth • Tele = distance • Scopos = to watch • Light and radiation • How astronomers gather info about space

2. Light • Visible light is a form of electromagnetic radiation. • Examples of electromagnetic radiation that you can’t see are radio waves and x-ray. Scientists have developed instruments that can detect these types. • Astronomers determine the size, distance and movement of space objects by studying its radiation.

3. Spectrum • White light separated into a range of colors is called a spectrum. • In a spectrum, the colors of visible light appear in the order of their wavelengths. • Wavelength is the distance between one wave peak and the next wave peak. Red light has the longest wavelength and purple the shortest. • Visible light is a small fraction of the Electromagnetic Spectrum

5. Telescopes • A telescope is a device that gathers electromagnetic radiation (light). • Telescopes provide images that are much clearer than what is seen with the naked eye because telescopes show radiation that eyes can’t detect. • Most telescopes gather radiation with a glass lens or a reflecting surface such as a mirror. Larger lenses and reflecting surfaces produce brighter and more detailed images.

6. Visible-light Telescopes • Reflecting Telescope – This type of telescope has a curved mirror that gathers light. The image comes into focus in front of the mirror. Many reflecting telescopes have a second mirror that reflects the image to recording equipment or to a lens called an eyepiece. • Remember: Reflecting because mirrors reflect an image!

7. Reflecting Telescope • Draw & Label: • Eyepiece • Primary mirror • Secondary mirror • Light

8. Visible-light Telescopes 2. Refracting Telescope – This type of telescope has an objective lens, or curved piece of glass, at one end of a long tube. The lens gathers light and focuses it to form an image near the other end of the tube. An eye piece magnifies this image. • Remember: Refracting because the curved lens changes the direction or deflects light!

9. Draw & Label: • Objective lens • Eyepiece

10. Most powerful visible light telescopes are built on mountain tops or in rural areas to avoid city lights. • The atmosphere interferes with light coming in from space. • The movement of the air in the atmosphere is what makes stars seem to twinkle

11. Mauna Kea Observatory Hawaii Griffith Observatory Los Angeles European Southern Observatory Chile

12. Radio Telescopes • Radio telescopes show where radio waves are being emitted by objects in space. Radio telescopes have a large, curved metal surface called a dish. (Parabola) • They are often found in groups with all dishes aimed the same way to gather waves to improve the quality of the image. • Because radio waves are so large they can penetrate the Earth’s atmosphere. What does this mean?

15. Space Telescopes • The Hubble telescope is a reflecting telescope that was placed into orbit in 1990. • Because it’s in space, the atmosphere does not interfere with imaging. • The lack of atmospheric interference allows the Hubble to produce very clear images. • Atmosphere blocks most x-rays and gamma rays

18. Closure • In ISN Answer: • How are visible light, radio waves, and other forms of electromagnetic radiation different from each other? • What function do mirrors serve in reflecting telescopes? • Why are some telescopes placed high on mountains or in orbit around Earth? HW: Research Percival Lowell and Edwin Hubble and write a short paragraph about each man and how important their contribution is to scientific knowledge.