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Chapter 19 Bellringer What are stars made of?
Section 1 Stars Bellringer What are stars made of? How do stars differ from one another? Do stars move?
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Chapter 19 Section 1 Stars Objectives Describe how color indicates the temperature of a star Explain how a scientist can identify a star’s composition Describe how scientists classify stars.
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Chapter 19 Objectives, continued
Section 1 Stars Objectives, continued Compare absolute magnitude with apparent magnitude. Identify how astronomers measure distances from Earth to stars. Describe the difference between the apparent motion and the actual motion of stars.
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Chapter 19 Section 1 Stars Color of Stars Because a blue flame is hotter than a yellow or red flame, we can conclude that blue stars are hotter than yellow or red stars.
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Chapter 19 Composition of Stars
Section 1 Stars Composition of Stars A star is made of different elements in the form of gases. The gases in the atmosphere of a star absorb different wavelengths of light depending on which elements make up the gases. The light from a star indicates which elements make up that star.
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Composition of Stars continued
Chapter 19 Section 1 Stars Composition of Stars continued The Colors of Light A prism breaks white light into a rainbow of colors called a spectrum. An instrument called a spectrograph is used to break a star’s light into a spectrum. The spectrum of a star will vary depending on which elements are present.
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Composition of Stars continued
Chapter 19 Section 1 Stars Composition of Stars continued Making an ID Emission lines are lines made when certain wavelengths,of light, or colors, are given off by hot gasses. Each elements produces a unique set of emission lines, which allows them to be used to identify the elements in a star.
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Emission Lines of Elements
Chapter 19 Section 1 Stars Emission Lines of Elements
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Composition of Stars, continued
Chapter 19 Section 1 Stars Composition of Stars, continued Trapping the Light––Cosmic Detective Work A star’s spectrum is made of dark emission lines. A star’s atmosphere absorbs certain colors of light, which causes black lines to appear.
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Composition of Stars, continued
Chapter 19 Section 1 Stars Composition of Stars, continued Identifying Elements Using Dark Lines Because a star’s atmosphere absorbs some colors of light, the spectrum of a star is called an absorption spectrum. It can be used to identify some of the elements in a star’s atmosphere.
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Continuous Spectrum and Absorption Spectrum
Chapter 19 Section 1 Stars Continuous Spectrum and Absorption Spectrum
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Chapter 19 Classifying Stars
Section 1 Stars Classifying Stars Differences in Temperature Stars are now classified by how hot they are. Differences in Brightness The brightest star, Sirius, has a magnitude of The dimmest star that can be seen with a microscope has a magnitude of 29.
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Magnitude of Stars in Big Dipper
Chapter 19 Section 1 Stars Magnitude of Stars in Big Dipper
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Chapter 19 How Bright Is That Star?
Section 1 Stars How Bright Is That Star? Apparent Magnitude The brightness of a light or star is called apparent magnitude. Absolute Magnitude Absolute magnitude is the actual brightness of a star.
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Chapter 19 Distance to the Stars
Section 1 Stars Distance to the Stars Because stars are so far away, astronomers use light-years to measure the distances from Earth to the stars. A light year is the distance that light travels in a year. Parallax is the apparent shift in the position of an object when viewed from different locations. Measuring parallax enables scientists to calculate the distance between a star and the Earth.
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Chapter 19 Section 1 Stars
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Finding the Distance to Stars: Parallax
Chapter 19 Section 1 Stars Finding the Distance to Stars: Parallax Click below to watch the Visual Concept. You may stop the video at any time by pressing the Esc key. Visual Concept
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Chapter 19 Motions of Stars
Section 1 Stars Motions of Stars The Apparent Motion of Stars If you look at the night sky long enough, the stars also appear to move. The Actual Motion of Stars The apparent motion of the sun and stars in our sky is due to Earth’s rotation. But each star is also moving in space. Their actual movements, however, are difficult to see.
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Apparent Motion of Stars
Chapter 19 Section 1 Stars Apparent Motion of Stars
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Chapter 19 Section 1 Stars Actual Motion of Stars
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