1. Exploring Space
Section 1: Radiation From Space

2. A. Electromagnetic Waves
1. Light from the past
a. Light seen from stars, may have left
that star many years ago.
b. Light and other energy leaving a star
are forms of radiation.
c. Radiation is energy that’s transmitted
from one place to another by
electromagnetic waves.
d. Because of this radiation, its called
electromagnetic radiation

3. B. Electromagnetic Radiation
1. Sound waves, a type of mechanical
waves can’t travel through empty space.
a. Then how do we hear the voices of
astronauts while they are in space?
b. When they speak into a microphone, the
sound is converted into electromagnetic
waves called radio waves.
c. They are then converted back into sound by
electronic equipment and audio speakers.

4. 2. Types of electromagnetic radiation
a. Radio waves, visible light, gamma rays, X-
rays, ultraviolet waves, infrared waves, and
microwaves.
3. Measured in wavelength and frequency.
a. Wavelength is the distance from the top of
one wave to the next.
b. Frequency is the number of wavelengths that
pass by a certain point in one second.
c. As wavelength increases; frequency
decreases and vice versa.

7. The Electromagnetic Spectrum

8. C. Speed of Light
1. Light is part electricity and part magnetism
2. Speed of light is 3.8 X 108 m/s or 300,000
km/s
3. All electromagnetic waves travel at the speed
of light.
4. Universe is so large it takes millions of years
from the light from some stars to reach the
Earth.
5. Once electromagnetic radiation from stars
and other objects reach Earth, we can use it
to learn about the source of the
electromagnetic radiation.

9. 6. One tool used for observing electromagnetic
radiation from distant sources is a
TELESCOPE.

10. Water Found on Mars!

11. D. How we use Electromagnetic Waves
1. Light from the Past
a. Stars are images from the past.
b. Light from stars takes time to travel through
space.
c. Our Sun is about 150 million kilometers away
(about 8 minutes travel time)
d. Alpha Centauri (our closest neighboring star) is
about 40 Trillion Kilometers away; about 4.2 years
travel time.
e. Light travels at 300,000 km/sec or 186,000
miles/second.
f. Light travels 9.5 trillion kilometers in a year (this is
one light year).
g. A light year measures both distance and time!!!

13. E. Radio Waves
1. Longest wavelength: 105 to 10-1 meters.
2. Lowest frequency: 103 to 109 Hertz
3. Used for communication and information transfer.

14. F. Microwaves
1. Wavelength: 10 -1 to 10 -3 meters & Frequency:
109 to 1011 Hertz.
2. Used for communication, Information transfer and
cooking.

15. G. Infrared
1. Wavelength: 10 -3 to 10 -6 meters & Frequency:
1011 to 1014 Hertz
2. Used for heat production and Thermography.
3. “Seen” by some insects and animals.

16. H. Visible Light
1. Wavelength: 10 -7 meters & Frequency:
1015 Hertz
2. Colors seen by human eyes

17. I. Ultraviolet
1. Wavelength: 10 -7 to 10 -9 meters & Frequency:
1015 to 1017 Hertz
2. “Seen” by some insects
3. Cause of tanning, sunburn, skin cancer
4. Degrades rubber & plastic materials (fades cloth
& paper)

18. J. X-Rays
1. Wavelength: 10 -9 to 10 -11 meters &
Frequency: 1017 to 1019 Hertz
2. Bone scans, Information transfer

19. K. Gamma Rays
1. High level radiation (Very Dangerous)
2. Shortest wavelength: 10 -11 to 10 -15
Meters
3. Highest frequency : 1019 to 1023 Hertz

20. L. How We Use Telescopes
1. We use the electromagnetic spectrum to
observe space.
2. Optical Telescopes
a. Produce magnified images of objects.
b. Visible light is collected by mirrors or lenses and
then focused.
3. There are two types of telescopes.
a. Optical Telescopes (You need light for these)
b. Radio Telescopes.

21. M.Refracting Telescope (Optical)
1. Light from an object passes through a
convex objective lens and is bent to from an
image on the focal point.
2. The images is then magnified by the
eyepiece.
3. Limited in size
4. Worlds refracting mirror is Yerkes Refracting
Telescope
a. Just over a meter in diameter (distance
across)

22. Diagram of a Refracting
Telescope
Focal
Convex Lens Point Eyepiece

23. N.Reflecting telescopes
1. Light passes trough the telescope housing to
a concave mirror
2. Mirror reflects light to a flat mirror
3. Flat mirror redirects light to a focal point
4. Light passes through the focal point, to the
eyepiece
5. Eyepiece magnifies image
6. Largest in the world = 10 meters wide

24. Diagram of a Reflecting Telescope

25. O. Optical Telescope Uses:
1. Most “home” use telescopes are optical.
2. Used to see moon features and close
planets.
3. Scientific optical telescopes are housed in
OBSERVATORIES.
a. Observatories have domed shape roofs that open.
b. Observatories built on mountains or deserts, far
away from cities.
1. Prevents city light interference and pollution blurring.
2. Decreases “down time” due to poor weather.
c. Not all telescopes are housed in observatories.

26. P. Radio Telescopes.
1. Designed to pick up radio
waves emitted from space.
2. Usable in any weather!!!
a. Radio waves are concentrated by
dish shaped body.
b. Concentrated waves are directed
to a focal point.
c. Focal point is fixed with a
receiver.
d. Receiver transmits information to
a computer.

27. 3. Uses of a Radio Telescope
a. Detects objects deep in space.
b. Maps the Universe.
c. Searches for intelligent life in space.
4. Largest Radio Telescope in the world is 300
meters wide.

28. Radio Telescopes

29. Q. Hubble Telescope (Reflecting Telescope)
1. Launched in 1990 by the space shuttle Discovery.
2. Since Hubble did not have to view space through the
Earth’s atmosphere, it should have produced very
clear images.
3. However there was a mistake in the largest mirror
used in the Hubble Telescope!!!!
4. Images were not as clear as expected.
5. December 1993 first set of repairs were fixed by
astronauts.
6. Has been repaired numerous times since.
a. Hubble Telescope Link/

30. End of Section 1