CH

Section 27.1: Tools of Astronomy

Section 27.2: The Moon

Section 27.3: The Sun-Earth-Moon System

The Sun-Earth-Moon System

ObjectivesDefine electromagnetic radiation.

Explain how telescopes work.

Describe how space exploration helps scientists learn about the universe.

Tools of AstronomySection 27.1

Review Vocabulary

refraction: occurs when a light ray changes direction as it passes from one material into another

Radiation emitted or reflected by distant objects allows scientists to study the universe.

Tools of AstronomySection 27.1

New Vocabulary

electromagnetic spectrum

refracting telescope

Tools of AstronomySection 27.1

reflecting telescope

interferometry

Radiation

The radiation from bodies throughout the universe that scientists study is called electromagnetic radiation.

This includes visible light, infrared and ultraviolet radiation, radio waves, microwaves, X rays, and gamma rays.

Tools of AstronomySection 27.1

RadiationThe electromagnetic spectrum consists of all types of electromagnetic radiation arranged according to wavelength and frequency.

Tools of AstronomySection 27.1

Radiation

Wavelength and frequency

Electromagnetic radiation is classified by wavelength, the distance between peaks on a wave, and frequency, the number of waves or oscillations that pass a given point per second.

Tools of AstronomySection 27.1

Radiation

Wavelength and frequency

Frequency is related to wavelength by the mathematical relationship c = λf, where c is the speed of light (3.0 × 108 m/s), λ is the wavelength, and f is the frequency.

Tools of AstronomySection 27.1

Telescopes

Telescopes provide the ability to observe wavelengths beyond what the human eye can detect. They collect electromagnetic radiation from distant objects and focus it so that an image of the object can be recorded.

Telescopes can also collect light over periods of minutes or hours.

Tools of AstronomySection 27.1

TelescopesRefracting and reflecting telescopes

Refracting telescopes use lenses to focus visible light.

Tools of AstronomySection 27.1

Reflecting telescopes use mirrors to focus visible light.

Tools of AstronomySection 27.1

TelescopesRefracting and reflecting telescopes

Telescopes

Telescopes using non-visible wavelengths

For all telescopes, the goal is to bring as much electromagnetic radiation as possible into focus.

Infrared and ultraviolet radiation can be focused by mirrors in a way similar to that used for visible light.

Tools of AstronomySection 27.1

Telescopes

Telescopes using non-visible wavelengths

X rays cannot be focused by normal mirrors, and thus special designs must be used.

Gamma rays cannot be focused, so telescopes designed to detect this type of radiation can determine only the direction from which the rays come.

Tools of AstronomySection 27.1

Telescopes

Telescopes using non-visible wavelengths

A radio telescope collects the longer wavelengths of radio waves with a large dish antenna and reflects them to a point above the dish. There, a receiver converts the radio waves into electric signals that can be stored in a computer for analysis.

Tools of AstronomySection 27.1

TelescopesTelescopes using non-visible wavelengths

The data collected from radio telescopes are converted into visual images by a computer. The image resolution can be improved using interferometry, a process that links separate telescopes so they act as one telescope, producing more detailed images as the distance between the telescopes increases.

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Space-Based Astronomy

Space-based telescopes allow astronomers to study radiation that would be blurred by our atmosphere.

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Space-Based Astronomy

Hubble Space Telescope

The Hubble Space Telescope was designed to obtain sharp visible-light images without atmospheric interference and to make observations in infrared and ultraviolet wavelengths.

Tools of AstronomySection 27.1

Please click the image above to view the interactive table.

Tools of AstronomySection 27.1

Space-Based Astronomy

Spacecraft

Spacecraft make observations from above Earth’s atmosphere and can also be sent directly to the bodies being observed.

Robotic probes are spacecraft that can make close-up observations and sometimes land to collect information directly.

Tools of AstronomySection 27.1

Space-Based AstronomyHuman spaceflight

The space shuttle provides an environment for scientists to study the effects of weightlessness on humans, plants, the growth of crystals, and other phenomena.

Because shuttle missions last a maximum of just 17 days, long-term effects must be studied in space stations.

Tools of AstronomySection 27.1

Space-Based AstronomySpinoff technology

Many technologies that were originally developed for use in space programs are now used by people around the world. More than 1400 different NASA technologies, such as cordless tools, have been passed on to commercial industries for common use; these are called spinoffs.

Tools of AstronomySection 27.1

ObjectivesDescribe the history of lunar exploration.

Recognize lunar properties and structures.

Identify features of the Moon.

Explain the theory of how the Moon formed.

The MoonSection 27.2

lava: magma that flows onto the surface from the interior of an astronomical body

Review Vocabulary

The Moon, Earth’s nearest neighbor in space, is unique among the moons in our solar system.

The MoonSection 27.2

New Vocabulary

albedo

highland

maria

impact crater

ejecta

ray

rille

regolith

The MoonSection 27.2

Exploring the Moon

Most knowledge of the Moon comes from explorations by space probes and from landings by astronauts.

The MoonSection 27.2

Exploring the Moon

The first step toward reaching the Moon was in 1957, when the Soviet Union launched the first artificial satellite, Sputnik I.

Four years later, Soviet cosmonaut Yuri A. Gagarin became the first human in space.

The MoonSection 27.2

Exploring the Moon

In 1957, the United States launched the first American, Alan B. Shepard, Jr., into space during Project Mercury.

This was followed by Project Gemini that launched two-person crews.

The MoonSection 27.2

Exploring the Moon

On July 20, 1969, the Apollo program landed Neil Armstrong and Edwin “Buzz” Aldrin on the Moon during the Apollo 11 mission.

After a gap of many years, scientists hope to return to the Moon before 2029.

The MoonSection 27.2

The Lunar Surface

The albedo of the Moon, the percentage of incoming sunlight that its surface reflects, is very small—only about 7 percent.

In contrast, Earth has an average albedo of nearly 31 percent.

The MoonSection 27.2

The Lunar Surface

Lunar highlands are heavily cratered regions of the Moon that are light in color and mountainous.

Maria are dark, smooth plains, which average 3 km lower in elevation and have few craters.

The MoonSection 27.2

The Lunar Surface

Lunar craters

The craters on the Moon, called impact craters, formed when objects from space crashed into the lunar surface.

The material blasted out during these impacts fell back to the Moon’s surface as ejecta.

The MoonSection 27.2

The Lunar Surface

Lunar craters

Some craters have long trails of ejecta, called rays, that radiate outward from the impact site.

Rilles are meandering, valleylike structures that might be collapsed lava tubes.

The MoonSection 27.2

The Lunar Surface

Lunar properties

Earth’s moon is unique among all the moons in the solar system.

1.It is one of the largest moons compared to the radius and mass of the planet it orbits.

2. It is a solid, rocky body, in contrast with the icy compositions of other moons of the solar system.

The MoonSection 27.2

The Lunar Surface

Lunar properties

3.The Moon’s orbit is farther from Earth relative to the distance of most moons from the planets they orbit.

4. Moon’s albedo is 7%. Earth’s 31%.

The MoonSection 27.2

The Lunar Surface

Lunar properties

5.The Moon is made up of minerals similar to those of Earth—mostly silicates.

The highlands are mostly lunar breccias, which are rocks formed by the fusion of smaller rocks during impacts. The maria are predominantly basalt that contains no water.

The MoonSection 27.2

Please click the image above to view the interactive table.

The MoonSection 27.2

History of the Moon

The Moon is approximately 3.8 to 4.6 billion years old, about the same age as Earth.

Scientists theorize that the Moon was heavily bombarded during its first 800 million years. This caused the breaking and heating of surface rocks and resulted in a layer of loose, ground-up rock called regolith on the surface.

The MoonSection 27.2

History of the MoonLayered structure

Scientists infer from seismic data that the Moon, like Earth, has a layered structure, which consists of the crust, upper mantle, lower mantle, and core.

The MoonSection 27.2

History of the Moon

Formation of maria

After the period of intense bombardment that formed the highlands, lava welled up from the Moon’s interior and filled in the large impact basins.

This lava fill created the dark, smooth plains of the maria.

The MoonSection 27.2

History of the Moon

Tectonics

Scientists think that the Moon is not tectonically active because the Moon has no active volcanoes and no significant magnetic field.

The MoonSection 27.2

Formation

The Moon probably formed as the result of a collision between Earth and a Mars-sized object about 4.5 bya when the solar system was forming.

The MoonSection 27.2

FormationThe impact theory of the Moon’s formation states that material ejected from Earth and from the striking object eventually merged to form the Moon.

The MoonSection 27.2

CH Key Concepts

Section 27.1 Tools of Astronomy

Radiation emitted or reflected by distant objects allows scientists to study the universe.

Telescopes collect and focus electromagnetic radiation emitted or reflected from distant objects.

Electromagnetic radiation is classified by wavelength and frequency.

Study Guide

CH

The two main types of optical telescopes are refractors and reflectors.

Space-based astronomy includes the study of orbiting telescopes, satellites, and probes.

Technology originally developed to explore space is now used by people on Earth.

Study Guide Key Concepts

Section 27.1 Tools of Astronomy

CH

The Moon, Earth’s nearest neighbor in space, is unique among the moons in our solar system.

Astronomers have gathered information about the Moon using telescopes, space probes, and astronaut exploration.

Like Earth’s crust, the Moon’s crust is composed mostly of silicates.

Section 27.2 The Moon

Study Guide Key Concepts

CH

Surface features on the Moon include highlands, maria, ejecta, rays, and rilles. It is heavily cratered.

The Moon probably formed about 4.5 bya in a collision between Earth and a Mars-size object.

Section 27.2 The Moon

Study Guide Key Concepts

CH

Gamma rays move through space at a greater speed than do radio waves.

a. true

b. false

27.1 Section Questions

The Sun-Earth-Moon System

CH

Which objects produce the image in a refracting telescope?

a. mirrors

b. lamps

c. lenses

d. prisms

27.1 Section Questions

The Sun-Earth-Moon System

CH

What advantage do telescopes in space have over similar instruments on Earth’s surface?

a. The telescopes are closer to the object.

b. The telescopes are above the atmosphere.

c. The telescopes are safe from damage.

d. The telescopes are always in the dark.

27.1 Section Questions

The Sun-Earth-Moon System

CH

The Moon has a lower density than that of Earth.

a. true

b. false

27.2 Section Questions

The Sun-Earth-Moon System

CH

a. ejecta

b. rays

c. rilles

d. highlands

Which term refers to valleylike structures on the Moon that might be lava tubes?

27.2 Section Questions

The Sun-Earth-Moon System

CH

Which theory about how the Moon formed is most accepted?

a. The Moon was captured by Earth.

b. The Moon condensed with Earth.

c. A Mars-sized object struck Earth.

d. A piece broke off of Earth.

27.2 Section Questions

The Sun-Earth-Moon System