Tour of the EMS 05 - Visible Light Waves

Summary

This script explores the significance of visible light within the electromagnetic spectrum, detailing its role in scientific discovery and our perception of the world. It explains how visible light, with wavelengths from violet to red, reveals the composition and temperature of celestial bodies, influences Earth's atmospheric appearance, and aids in monitoring environmental changes. The script also discusses the use of laser altimeters for topographic mapping and the Hubble Space Telescope's contributions to our understanding of the universe.

Takeaways

• 🌈 All electromagnetic radiation is considered light, but only a small portion of it is visible to the human eye.
• 👀 Visible light is a narrow band of the electromagnetic spectrum that our eyes can detect, ranging from violet at 380 nanometers to red at 700 nanometers.
• 🔍 Isaac Newton's prism experiment in 1665 demonstrated that white light is composed of a spectrum of colors, debunking the idea that a prism colors light.
• 🔬 Visible light holds scientific clues that can reveal the physical properties and composition of celestial objects.
• 🌍 Earth's blue appearance is due to the scattering of blue light by atmospheric particles, which is more pronounced when the Sun is low.
• 🌅 The color of sunlight changes during a sunset because shorter wavelengths like blue are scattered more, allowing longer wavelengths like red and yellow to dominate.
• 🌡️ The color of a celestial body, such as a star, indicates its temperature; hotter objects emit shorter wavelength light.
• 🌎 Visible and infrared data from satellites like NASA's Landsat are used to monitor changes on Earth, including vegetation and volcanic activity.
• 🚀 NASA's Mars landers have sent back visible light images, giving us a sense of what it's like to stand on another planet.
• 🌌 Visible light, as captured by the Hubble Space Telescope, allows us to explore and understand the farthest reaches of the universe.

Q & A

What is the range of wavelengths for visible light?

Visible light has wavelengths ranging from violet at 380 nanometers to red at 700 nanometers.

What did people believe about the color of sunlight before Newton's experiment?

Before Isaac Newton's experiment in 1665, people thought that a prism colored the Sun's white light as it bent and spread a sunbeam.

How did Newton demonstrate that white light is composed of colored light?

Newton used two prisms to demonstrate that white light is made up of bands of colored light, and by using a second prism, he showed that these bands could be recombined to make white light again.

What can visible light reveal about the physical condition and composition of objects in the universe?

Visible light contains scientific clues that reveal hidden properties of objects, such as minute gaps in energy at specific wavelengths that can identify the physical condition and composition of stellar and interstellar matter.

Why does Earth's atmosphere generally appear blue?

Earth's atmosphere generally looks blue because it contains particles of nitrogen and oxygen that are just the right size to scatter energy with the wavelength of blue light.

How does the color of the Sun change as it sets and why?

When the Sun is low in the sky, light travels through more of the atmosphere, and more blue light is scattered out of the beam of sunlight before it reaches the eyes. Only the longer red and yellow wavelengths are able to pass through, often creating breathtaking sunsets.

How can scientists determine the composition of an atmosphere by observing visible light?

Scientists can learn the composition of an atmosphere by considering how atmospheric particles scatter visible light, which can reveal the presence and size of particles in the atmosphere.

What does the color of a star indicate about its temperature?

The color of a star indicates its temperature; for example, if the Sun's surface were cooler, it would look reddish, and if it were hotter, it would look blue.

How do NASA's instruments use visible light to study changes on Earth?

NASA instruments use visible light to study changes on Earth by combining visible and infrared data to assess damage from events like volcanic eruptions, and to monitor changes in cities, neighborhoods, forests, and farms over time.

What is the purpose of the Mars Orbiting Laser Altimeter and how does it work?

The Mars Orbiting Laser Altimeter sends a laser pulse to the surface of Mars, and sensors measure the time it takes for the laser signal to return, allowing the calculation of the distance from the satellite to the surface and creating a topographic map of the planet's surface.

How has visible light from the Hubble Space Telescope contributed to our understanding of the universe?

Visible light captured by the Hubble Space Telescope has created countless images that have sparked our imagination, inflamed our curiosity, and increased our understanding of the universe by revealing distant celestial objects and phenomena.

Outlines

00:00

🌈 The Spectrum of Visible Light

This paragraph discusses the nature of electromagnetic radiation, emphasizing that visible light is a small part of the spectrum that humans can perceive. It explains that the Sun's light, which appears white, is actually composed of a range of colors from violet (380 nm) to red (700 nm). Isaac Newton's 1665 experiment with prisms demonstrated that white light is made up of these colors. Visible light is crucial for scientific analysis, revealing the physical properties and composition of celestial bodies through minute energy gaps at specific wavelengths. Human eyes cannot detect these subtle changes, but scientific instruments can. The paragraph also explains how the scattering of light by atmospheric particles gives Earth's sky its blue color and how the Sun's color indicates its temperature.

Keywords

💡Electromagnetic Radiation

Electromagnetic radiation is a form of energy that includes a spectrum of waves of different frequencies and wavelengths, such as radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays. In the context of the video, it is emphasized that all types of light, including visible light, are forms of electromagnetic radiation. The video underscores the importance of visible light as a subset of this broader spectrum that our eyes can perceive, highlighting its role in gathering information about the world around us.

💡Visible Light

Visible light is the small portion of the electromagnetic spectrum that is detectable by the human eye. It ranges from wavelengths of about 380 nanometers (violet) to 700 nanometers (red). The video explains that visible light is crucial for our perception of the world, and it is the focus of the script as it discusses how our eyes rely on this narrow band of electromagnetic radiation to interpret our surroundings.

💡Spectrum

The term 'spectrum' in the video refers to the continuous band of colors or wavelengths that make up light, particularly the electromagnetic spectrum. The script mentions that the Sun's light, which appears white, is actually a combination of all the colors of the spectrum, each with specific wavelengths. This concept is foundational to understanding the composition and behavior of light as discussed in the video.

💡Prism

A prism is an optical device that splits light into its constituent spectral colors by refracting the light at different angles for each color. The video references Isaac Newton's experiment with prisms to demonstrate that white light is composed of a spectrum of colors. This experiment was pivotal in disproving the then-common belief that a prism colored white light and instead showed that white light is made up of multiple colors.

💡Wavelength

Wavelength is the physical length of a single wave, measured from one peak to the next. In the video, wavelengths are discussed in the context of visible light, with specific mention of the range from violet (380 nanometers) to red (700 nanometers). Wavelength is key to understanding how different colors of light interact with matter and how they can be used to analyze the properties of distant objects in the universe.

💡Scattering

Scattering in the video refers to the process by which light is deflected or dispersed by particles in a medium, such as Earth's atmosphere. The script explains that the blue color of the sky is due to the scattering of shorter blue light wavelengths by atmospheric particles, which is a phenomenon that scientists use to understand the composition of the atmosphere and the nature of light itself.

💡Atmosphere

The atmosphere is the layer of gases surrounding a planet, and in the video, it is discussed in relation to how it affects the scattering of light and the colors we perceive. The Earth's atmosphere, containing nitrogen and oxygen, scatters blue light, which is why the sky appears blue. This concept is used to explain how the study of light can reveal the composition and properties of planetary atmospheres.

💡Temperature and Color

The video explains the relationship between the temperature of an object and the color of light it emits. As an object's temperature increases, it emits light with shorter wavelengths, which appear as different colors. For instance, the Sun's yellow light is indicative of its surface temperature. This principle is used by scientists to determine the temperature of stars and other celestial bodies by observing their color.

💡Landsat Satellite

The Landsat satellite is mentioned in the video as a tool that combines visible and infrared data to study changes on Earth. Since 1972, it has been used to monitor changes in various environments, such as cities, forests, and farms. This technology exemplifies how visible light data, when combined with other forms of electromagnetic radiation, can be used for scientific research and environmental monitoring.

💡Laser Altimeter

A laser altimeter is a device that measures distances by emitting a laser pulse and timing how long it takes for the pulse to return after reflecting off a surface. In the video, the Mars Orbiting Laser Altimeter is highlighted as a technology that maps the topography of Mars by calculating the time it takes for a laser signal to return from the planet's surface. This illustrates how visible light, in the form of laser pulses, can be actively used to gather data about the physical characteristics of celestial bodies.

💡Hubble Space Telescope

The Hubble Space Telescope is noted in the video for its use of visible light to capture images of the universe that have expanded our understanding and imagination. The telescope's ability to observe and record visible light from distant galaxies and celestial phenomena has been instrumental in advancing astronomical research and deepening our knowledge of the cosmos.

Highlights

All electromagnetic radiation is considered light, but only a narrow band of it is visible to the human eye.

Visible light's wavelengths range from violet at 380 nanometers to red at 700 nanometers.

Isaac Newton's 1665 experiment disproved the idea that a prism colors white light, showing it is composed of multiple colors.

Visible light contains scientific clues that reveal the hidden properties of objects in the Universe.

Scientific instruments can detect minute energy gaps in visible light to identify the composition of stellar matter.

Earth's atmosphere appears blue due to the scattering of blue light by nitrogen and oxygen particles.

The color of sunlight changes during sunset as more blue light is scattered out of the beam, leaving red and yellow wavelengths.

The color of stellar objects indicates their temperature, with hotter objects radiating shorter wavelengths.

NASA EO-1 images combine visible and infrared data to distinguish between snow and volcanic ash, and to see vegetation more clearly.

NASA's Landsat satellite has been combining visible and infrared data since 1972 to study changes on Earth.

Visible light images from NASA's Mars landers have shown us what it would look like to stand on another planet.

NASA instruments can actively send out electromagnetic waves to map topography, such as the Mars Orbiting Laser Altimeter.

Laser altimeters on Earth orbit, like NASA's ICESat mission, collect data about the elevation of polar ice sheets.

Visible light helps us explore the far reaches of the universe, with the Hubble Space Telescope creating countless images that increase our understanding.

Transcripts

All electromagnetic radiation is light.

Visible light is the only part of the spectrum you can see.

For all your life, your eyes have relied on this one narrow band

of EM radiation to gather information about your world.

Though our Sun's visible light appears white, it is really the combined light

of the individual rainbow colors with wavelengths ranging from violet

at 380 nanometers to red at 700 nanometers.

Before Isaac Newton's famed experiment in 1665,

people thought that a prism somehow colored the Sun's

white light as it bent and spread a sunbeam. Newton disproved this

idea by using two prisms. To show that white light is made up of

the bands of colored light, Newton used a second prism to show that the bands

of colored light combine to make white light again. Visible light

contains important scientific clues that reveal hidden properties of objects

throughout the Universe. Minute gaps in energy at specific

visible wavelengths can identify the physical condition and composition

of stellar and interstellar matter. Human eyes aren't nearly

sensitive enough to detect these faint peaks, but

scientific instruments can. Scientists can learn the composition of an atmosphere

by considering how atmospheric particles scatter visible light.

Earth's atmosphere, for example, generally looks blue

because it contains particles of nitrogen and oxygen which are just

the right size to scatter energy with the wavelength of blue light.

When the Sun is low in the sky, however, light travels through more

of the atmosphere and more blue light is scattered out of the beam of sunlight before

it reaches your eyes. Only the longer red and yellow wavelengths

are able to pass through, often creating breathtaking sunsets.

When scientists look at the sky, they don't just see blue,

they see clues about the chemical composition of our atmosphere.

However, visible light reveals more than just composition.

As objects grow hotter, they radiate energy with a shorter

wavelength, changing color before our eyes. Watch a

flame shift from yellow to blue as it is adjusted to burn hotter.

In the same way, the color of stellar objects tell scientists

much about their temperature. Our Sun produces more yellow

light than any other color because of its surface temperature.

If the Sun's surface were cooler, say 3,000 degrees celcius,

it would look reddish, like the stars Antares and Betelgeuse.

If the Sun were hotter, say 12,000 degrees celcius,

it would look blue like the star Rigel.

Like all parts of the electromagnetic spectrum, visible light data can also

help scientists study changes on Earth such as assessing damage from

a volcanic eruption. This NASA EO-1 image

combines both visible and infrared data to distinguish between snow

and volcanic ash and to see vegetation more clearly.

Since 1972, images from NASA's Landsat satellite

have combined visible and infrared data to allow scientists

to study changes in cities, neighborhoods, forests, and farms over time.

Visible light images taken by NASA's

Mars landers have shown us what it would look like to stand on another planet.

They have expanded our minds, our imagination, and our understanding.

NASA instruments can do more than passively sense

radiation, they can also actively send out electromagnetic waves

to map topography. The Mars Orbiting Laser Altimeter

sends a laser pulse to the surface of the planet and sensors measure the amount of

time it takes for this laser signal to return. The elapsed time

allows the calculation of the distance from the satellite to the surface.

As the spacecraft flies above hills, valleys, craters, and other surface

features, the return time varies and provides a topographic

map of the planet's surface. Back in Earth orbit,

NASA's ICESat mission uses the same technique to collect data about

the elevation of the polar ice sheets to help monitor changes in the amount

of water stored as ice on our planet.

Laser altimeters can also make unique measurements of the heights of clouds,

the top of the vegetation canopy of forests, and can 'see' the distribution

of aerosols from sources such as dust storms and forest fires.

Finally, visible light helps us to explore the

far reaches of the universe that humans could not hope to reach physically.

Using visible light, the Hubble Space telescope has created

countless images that spark our imagination, inflame our curiosity,

and increase our understanding of the Universe.