Stars and Galaxies

Stars and Galaxies Chapter 25

Section 1 The Study of Stars • Objectives: • Describe the electromagnetic spectrum • Explain how reflecting and refracting telescopes work • Compare and Contrast optical telescopes and spectroscopes • Infer the relationship between the frequency of electromagnetic waves and their wavelength

Skills Warm-up • Star Words • Write as many words as you can to describe stars from just observing them. • Write something you know about stars but can’t tell by just looking at them. • Compare your words with your classmates.

Stars • Stars are swirling, glowing balls of ______ • There are > 200,000,000,000 billion • The _______ is very important to earth, but it is just an average ____ • Many other stars are much _______ and ________ • How are stars studied?

Electromagnetic Spectrum • All stars produce energy in the form of ___________ __________: • ________ ________ • ________ ________ • ________ • ________ • Each type of energy has a characteristic ________ and _________ • ____________ ________ - all types of electromagnetic wave energy, from very low frequency to very high frequency

Optical Telescope • Microscopes use _______ to collect visible light from ______ _______ and produce _________ that are much __________ • ________ __________ work the same way, using ________ or _________ to collect visible light • The only difference is that the light comes from a ______ ______ and _______ _______ • It then makes the distant object look ________ and _________

Optical Telescopes • ________ telescope – uses ______ to collect and focus visible light • _______ telescope – uses ______to collect and focus visible light

Optical Telescopes • The ______ a mirror or lens, the ______ the image it can make • But, if they get too big, they _____ from their own _______ • The telescope with the largest single mirror (5 m in diameter) is in the _____ _________ in California

Spectroscopes • A star’s ______ _______ has a characteristic spectrum of light of different wavelengths because each ________ __________ in the star blocks particular wavelengths of light • By looking at a star’s ________, scientists can figure out what its _________ ________ is • A _________ contains a _______ to separate the light and a small optical telescope to see the spectrum • Stars contain ~ 75% ________ and 22% _______

Radio Telescopes • Collect ______ _______ from space • ________ _______collects waves that are reflected to the antenna and then ___________ • Good for studying -______ and ________ and have helped us learn about our own ________

Activity • Work in pairs • Complete Skills Worksheet 25.1 • Please hand in completed worksheet by tomorrow – if necessary, finish for homework

Section 2 Characteristics of Stars • Objectives: • Relate the temperature of a star to its color • Explain how measurements of parallax are used to measure a star’s distance from earth • Contrast absolute magnitude and apparent magnitude • Interpret data from an H-R diagram

Skills Warm-up • Stars in the Sky • Make a list of the sun’s characteristics. • Which of these do you think are shared by all stars? • Which characteristics of the sun do you think are different from other stars?

Star Classification • Scientists classify stars according to : • _________ • _________ • _________ • _________

Color and Temperature • The color of a star is related to its ___________

Distance of Stars • Hold your finger in front of your face. • Look at it with your left eye closed. • Then look at it with your right eye closed. • Does your finger seem to move or change position relative to the background?

Distance of Stars • Now find an object across the classroom from you. • Look at it with your left eye closed. • Then look at it with your right eye closed. • Does this object move position as much as your finger did?

Distance of Stars • ___________– apparent change in the position of an _______ due to change in position of the __________ • Scientists use parallax to determine the _________ of a star from __________ • As earth moves around the sun, _______ stars appear to ______ position relative to more __________ stars • The ________ a star is to earth, the __________ its apparent change of position • Measurements of change in position can be ___________ into measurements of distance

Distance of Stars • Distances of stars are so ________ - you can’t use any normal _______ _____ ____________ • Scientists use______________ • The distance that light, travelling at a speed of 310,000 km per second, will cover in 1 year • Equal to 9.5 trillion km • Proxima Centauri – ________ star to earth at 4.2 light-years • Most stars are hundreds of light-years away

Magnitude of Stars • ______________– brightness of stars • The ___________ the star, the _________ its number of magnitude • A star with a magnitude of -2 is brighter than one with a magnitude of 2 • ___________ magnitude – a star’s brightness from earth • Doesn’t really tell you how much light is given off • ___________ magnitude – actual brightness of a star from a standard distance

Hertzsprung-Russell Diagram • Two scientists graphed a large number of stars based on their ________ __________ and _____________ • 4 Types of Stars: • ______ __________ – stars grouped in a diagonal band from hot/bright to cool/dim • ____________ – very bright stars that range from cool to medium/hot • _______ _______ – medium bright but cool • _______ _______ – low magnitude but relatively hot

Section 3 Life Cycles of Stars • Objectives: • Explain how stars come into being • Describe the stages of a star’s lifecycle • Contrast the different ways in which high-mass and low-mass stars end their life cycles • Predict what will happen for the rest of the sun’s lifecycle

Skills Warm-up • The Life of Stars • List and describe each stage of the human life cycle. • How do you think the human life cycle is different from that of a star?

Star Lifecycle • Human life cycle lasts about _____ ________ • Born • Infant • Toddler • Child • Teenager • Adult • Senior citizen

Star Lifecycle • Stars are also _______, then _______ and eventually ______ • Star life cycle lasts _______ __ _______ • Stars in the sky are at _________ stages • Our sun is about ____ way through its ____________ year life cycle

Birth of a Star • ______– a cloud of _____ and ______ where stars are born • Made of mostly _________ with _______ and _______ • Gravity causes the spread out particles of matter to ___________ • Matter starts to heat up and becomes a____________ • Protostars don’t shine, but give off _________ energy • Eventually they become hot enough for ________ to occur and a star is born

Low Mass-Stars – mass is less than ______ that of the ______ • Low-Mass Star Lifecycle: • Begins as a____________star but gradually the supply of _________ is changed by fusion into _________ • _________ _________– • core of star starts to collapse • becomes hotter and denser • helium is converted to __________ • short part of life cycle • ________ __________– • Star cools and collapses inward to be a_________ dwarf • Eventually no light is given off and is a__________ dwarf

High Mass-Stars – mass is more than ____ that of the _____ • High-Mass Star Lifecycle: • Uses up __________ at a much faster rate • ____________ __________– • ___________ runs out • Core collapses • Outer layers expand greatly • ____________ _________– • Pressure builds up and causes a massive ____________ • When only tiny core of neutrons remains it becomes - • _________ _____– dense core of neutrons • ________ ________– so dense and gravity so strong nothing can escape it

Section 4 Galaxies and Star Groups • Objectives: • Describe the 4 types of galaxies • Explain what a constellation is and how it differs from a galaxy or star cluster • Explain how scientists know the universe is expanding • Predict how the constellations will look in the distant future

Skills Warm-up • Lions and Tigers and ….. • When you look at the sky on a clear night, what shapes do the stars make? • Draw what they look like to you.

Galaxies • ______– collection of _____, nebulae, _______, dust, and _______ that move through space as a unit – held together by gravity • There are at least __ ______ galaxies in the universe – ours is the______ ____

Types of Galaxies • _______– flat disk with a bulge in the middle • Have long spiral arms that swing out and rotate like a _________ • Contain large amounts of ____ and ______ • Example –_____ _____

Types of Galaxies • _____ ______– similar to spiral but arms are attached to a straight bar shape • Bar is much _______ and ________ than the arms • ______ common than spiral • Example –_______ _______

Types of Galaxies • __________– football shaped • Rotate differently than spirals – more ________ • Contain ______ gas and dust • Example –_______

Types of Galaxies • ________– don’t have regular shapes • _____ greatly in size • ____ common type • Example – _____ ________ ______

Constellations • _____ ________shaped like people, animals, or objects • There are ______ official constellations • The stars in constellations may look like they are close together from earth, but they are not • Constellations are important because • _______________________ • _______________________ • _______________________

Expansion of the Universe • ______ ______ _______: • 15 – 20 million years ago all matter in the universe was packed into one______ ________ • The fireball exploded, spreading ______ and ________ out in all directions • As matter cooled, the force of gravity pulled together the particles of matter to form_____ ____ _________ • The universe was born!!!

Expansion of the Universe • What’s the proof??? • The___________ Effect • The light waves from an object _____ ______from earth are spaced more ______ apart than if it were _______ _______ • The waves appear to have a longer _________ than they really have and shift to the _____ ______ of the visible light spectrum • All other galaxies have a red shift in their spectrums which means they are moving _____ from earth

Stars and Galaxies