Unit 1 The UniverseMrs. Williams

8th Grade

Big Idea: The sun is one of billions of stars in one of billions of galaxies in the universe.

Big Idea:

Our Place in Space

•Universe-space & all the matter & energy in it.•Galaxy- a large collection of stars, gas, & dust• There are an estimated 100 billion galaxies

in the universe.

M i l k y w ay g a l a x yE a r t h

U n i v e r s eS o l a r s y s t e m

Unit 1 Lesson 1 Structure of the Universe

Types of Galaxies• Spiral galaxies are shaped like

pinwheels. They have a central bulge from which two or more spiral arms extend.

• Elliptical galaxies look like spheres or ovals and do not have spiral arms.

• Irregular galaxies appear as splotchy, irregularly shaped “blobs.” They are very active areas of star formation. http://library.thinkquest.org/C0110277/images/galaxies.gif

Unit 1 Lesson 1 Structure of the Universe

What Makes Up the Universe?

•Solar system- the collection of large & small bodies that orbit our central star, the sun.• Planet-spherical body that orbits the

sun.

Unit 1 Lesson 1 Structure of the Universe

Terrestrial Planets

• Terrestrial Planets- rocky, dense, and relatively small.•Mercury, Venus, Earth and Mars

http://ut-images.s3.amazonaws.com/wp-content/uploads/2008/04/mercurycomparison.jpg

Unit 1 Lesson 1 Structure of the Universe

•Gas giant planets - have thick, gaseous atmospheres; small, rocky cores; and ring systems of ice, rock, and dust.

• Jupiter, Saturn, Uranus, and Neptune.

Unit 1 Lesson 1 Structure of the Universe

Small Bodies in the Universe

•Moons- orbit most of the planets. Earth has only one moon, but Jupiter has more than 60.• The solar system has other small bodies, including • Dwarf planets• Comets• Asteroids• Meteoroids

• http://home.earthlink.net/~meshellwg/w/www/images/comet.jpg

Unit 1 Lesson 1 Structure of the Universe

Measuring the Universe• Distances between most objects in the universe

are so large that astronomers measure distances using the speed of light.

•Light-year -the distance that light travels through space in one year.

• Light travels through space at about 300,000 km/s, or about 9.5 trillion kilometers in one year.

Unit 1 Lesson 1 Structure of the Universe

Reach For The Stars!

•Star - large celestial body that is composed of gas & emits light. • Most stars are composed almost entirely

of hydrogen and helium.• Stars emit light and vary in brightness,

size and temperatures.

Unit 1 Lesson 1 Structure of the Universe

http://www.le.ac.uk/ph/faulkes/web/images/stars.jpg

You’re a Shining StarHow is star brightness measured?

• Apparent magnitude -measure of a star’s brightness as seen from Earth.

– Luminosity- actual brightness of a star.

• Absolute magnitude -measure of how bright a star would be if the star were located at a standard distance.

Unit 1 Lesson 2 Stars

Too HOT to Handle

• Surface temperatures of Stars are measured by their COLORCOLOR SURFACE TEMPERATURE (˚C)

Blue Above 25,000

Blue-white 10,000-25,000

White 7,500-10,000

Yellow-white 6,000-7,500

Yellow 5,000-6,000

Orange 3,500-5,000

Red Below 3,500

Unit 1 Lesson 2 Stars

Stars differ greatly in size

• White dwarfs - Very small stars have about the same radius as Earth, which is approximately 0.01 solar radius.

• Giant stars - Very large stars, typically have sizes between 10 and 100 times the sun’s radius.

• Supergiants - Some rare, extremely large stars have sizes of up to 1,000 solar radii.

Unit 1 Lesson 2 Stars

A Star Is Born

http://dsc.discovery.com/convergence/hubble/hits/gallery/garden4_lrg.jpg

What is the life cycle of a star?

• Stars form in nebulae.

• Nebula -large cloud of gas and dust. It is composed mainly of hydrogen and helium, with small amounts of heavier elements.

Unit 1 Lesson 3 The Life Cycle of Stars

Birth of a Star•Nuclear fusion –high temp & pressure cause two or more low-mass atomic nuclei to form a heavier nucleus. Gives off light.•Occurs for most of the stars life.

Unit 1 Lesson 3 The Life Cycle of Stars

The Lightweights

• Low-mass stars- The sun is a low mass, medium size star.– Giants-large red stars due to star’s

outer atmosphere expanding after active fusion ends.

–White dwarf -hot, dense core of matter that remains from the collapse of a low-mass star. It is about the size of Earth.

Unit 1 Lesson 3 The Life Cycle of Stars

The Heavyweights• High mass stars– Supergiant-produces heavier elements

like carbon– Supernova -gigantic explosion in which

a high-mass star collapses, throwing its outer layers into space. But its core remains.

–Neutron star -small, incredibly dense ball of closely packed neutrons.

– Black hole -invisible object with gravity so great that nothing, not even light, can escape it.

Unit 1 Lesson 3 The Life Cycle of Stars

A Graphic Display•H-R diagram –graph that shows the relationship between the stars surface temperature & absolute magnitude (brightness/luminosity)

Main sequence -region of the diagram where stars spend most of their lives. (actively fusing hydrogen)

Unit 1 Lesson 3 The Life Cycle of Stars