Unit E Lesson 7: Seeing ‘Beyond the Visible’
Completion requirements
Unit E Lesson 7: Seeing ‘Beyond the Visible’
|
Learning Targets |
Big Question: How can we see ‘beyond the visible’?
Our sight is based on being able to sense light energy with our eyes. Light is only one kind of energy, and we have developed technologies to detect other types of energy as it travels through the universe.
Our sight is based on being able to sense light energy with our eyes. Light is only one kind of energy, and we have developed technologies to detect other types of energy as it travels through the universe.
At the end of this inquiry, you should be able to answer the following questions:
- What is the electromagnetic spectrum?
-
What type of energy are radio waves, infrared waves, and X-rays?
- Why are radio telescopes so important to information gathering?
- How does radio interferometry benefit information gathering?
- What is a space probe?
- What are an advantage and a disadvantage of using a space probe?
Pages 440 to 445 in your textbook will help you answer these questions.
Introduction
Medical Imaging
The images available to doctors these days are quite incredible, and are made possible through imaginative applications of electromagnetic radiation.
X-rays have been used in medicine for a long time, but they way they are used continues to undergo advancements. The computerized tomography scan, or CT scan, is a device that uses X-rays from many angles, with the help of computers, to produce 3D images of the inside of the human body.
The images available to doctors these days are quite incredible, and are made possible through imaginative applications of electromagnetic radiation.
X-rays have been used in medicine for a long time, but they way they are used continues to undergo advancements. The computerized tomography scan, or CT scan, is a device that uses X-rays from many angles, with the help of computers, to produce 3D images of the inside of the human body.
Figure 1 – CT Scans of the human head.
Background Information
What does it mean to see ‘beyond the visible’?
Visible light is responsible for everything that we see. Visible light is only a small section of the electromagnetic spectrum. The electromagnetic spectrum covers all forms of electromagnetic energy, most of which are not visible to the human eye, that are released by certain electromagnetic processes.
Many of these forms of electromagnetic energy – radio waves, infrared waves, and X-rays – are emitted by stars and galaxies. Each of the different parts of the electromagnetic spectrum differs by the waves frequency and wavelength. These forms of electromagnetic energy provide valuable information about the nature of the Universe.
Interactive
Electromagnetic Spectrum
-
The BrainPOP video Electromagnetic Spectrum, reviews electromagnetic energy.
You will need a username and password to access the video.
- Username: 0099
-
Password: students
-
Click here to complete the quiz on the
Electromagnetic Spectrum. Remember to check your answers at the end!
Radio Telescopes
Both reflecting and refracting telescopes focus light to produce images. This means that limitations are inherent in their usage. Because bright sunlight overwhelms starlight, optical telescopes can be used only at night, and because clouds absorbed much of the visible light, observation was dependent on the weather. Radio telescopes provided a solution to both of these problems. Radio waves are longer than the waves of visible light, so they can reach the ground undistorted by the atmosphere. As well, radio waves can observe space during the day and were unaffected by cloud cover.
Using the same technology as that used by ultrasound and sonar, radio telescopes receive radio waves to produce an image. Radio telescopes were able to detect radio waves from the constellations of Cygnus and Cassiopeia and to detect that Mercury has water ice on the floors of craters at its North Pole.
Both reflecting and refracting telescopes focus light to produce images. This means that limitations are inherent in their usage. Because bright sunlight overwhelms starlight, optical telescopes can be used only at night, and because clouds absorbed much of the visible light, observation was dependent on the weather. Radio telescopes provided a solution to both of these problems. Radio waves are longer than the waves of visible light, so they can reach the ground undistorted by the atmosphere. As well, radio waves can observe space during the day and were unaffected by cloud cover.
Using the same technology as that used by ultrasound and sonar, radio telescopes receive radio waves to produce an image. Radio telescopes were able to detect radio waves from the constellations of Cygnus and Cassiopeia and to detect that Mercury has water ice on the floors of craters at its North Pole.
Radio Interferometry
Just as multiple telescopes can be combined to improve the resolution of an image, several radio telescopes can be arranged in an array to work together as one telescope. The Very Large Array (VLA) in Socorro, New Mexico, provides the same resolving power as a single radio telescope with a dish 36 miles in diameter.
The VLA can select the type of information it gathers by altering the spacing between each dish. When the dishes are farther apart, the telescopes’ resolution is better. When the dishes are closer together, the resolution is less, but the telescope can receive information better about an object’s brightness and temperature.
Just as multiple telescopes can be combined to improve the resolution of an image, several radio telescopes can be arranged in an array to work together as one telescope. The Very Large Array (VLA) in Socorro, New Mexico, provides the same resolving power as a single radio telescope with a dish 36 miles in diameter.
The VLA can select the type of information it gathers by altering the spacing between each dish. When the dishes are farther apart, the telescopes’ resolution is better. When the dishes are closer together, the resolution is less, but the telescope can receive information better about an object’s brightness and temperature.
Space Probes
Researchers can benefit from information that is not available on the electromagnetic spectrum. Space probes are spacecraft containing equipment or robots that can study a wide range of features in space, on planets, moons, asteroids, and comets.
The first space probe to go to space was Sputnik 1 launched by the Soviet Union in 1957. Since then, many probes have travelled greater distances from Earth collecting information about the surfaces of other objects in space.
NASA has developed three types of space probes; interplanetary space probes, orbiters, and landers. Interplanetary probes simply fly by celestial bodies. Orbiters are placed in orbit around a celestial body in order to examine it for a number of years. Landers are probes designed to land on the surface of a celestial body in order to study a particular place on it.
Researchers can benefit from information that is not available on the electromagnetic spectrum. Space probes are spacecraft containing equipment or robots that can study a wide range of features in space, on planets, moons, asteroids, and comets.
The first space probe to go to space was Sputnik 1 launched by the Soviet Union in 1957. Since then, many probes have travelled greater distances from Earth collecting information about the surfaces of other objects in space.
NASA has developed three types of space probes; interplanetary space probes, orbiters, and landers. Interplanetary probes simply fly by celestial bodies. Orbiters are placed in orbit around a celestial body in order to examine it for a number of years. Landers are probes designed to land on the surface of a celestial body in order to study a particular place on it.
Watch
NASA is building a new telescope, the James Webb Telescope. This telescope will be able to see in a light
invisible to the human eye – infrared light.
As you watch the video "James Webb Space Telescope: Mission Trailer" consider the following questions. If the Hubble Space Telescope takes such amazing pictures, why is the James Webb Telescope necessary? What information will it provide that the Hubble cannot?
As you watch the video "James Webb Space Telescope: Mission Trailer" consider the following questions. If the Hubble Space Telescope takes such amazing pictures, why is the James Webb Telescope necessary? What information will it provide that the Hubble cannot?
Try It!
Practice Worksheet: Telescope Advantages Chart 3
- DOWNLOAD this practice worksheet (S9_UE_S2_L7_telescope3). If you prefer to use a Google Drive or PDF version of the worksheet, click here.
- Answer the questions on the worksheet as you work through the readings and videos in this lesson.
- When you are satisfied with your responses you can check your work by clicking on the "SUGGESTED ANSWERS" button below.
Wait! Don't view the suggested answers first. This practice work is not for marks, it is meant to help you check your understanding. Check the answers AFTER doing the questions! Keep the practice worksheet for study purposes. If you don't understand something, contact your teacher!
Figure 2 – A radio telescope array.
