Science Journals – 3-25-14

• The light from Alpha Centauri A takes 4.3 years to reach Earth. The light from Ross 154 takes 9.7 years to reach Earth. The light from Luyten 726-8A takes 8.7 years to reach Earth. The light from Procyon A takes 11.4 years to reach Earth. The light from Sirius B takes 8.1 years to reach Earth.

1. What is the order of the following stars from the closest to Earth to the farthest from Earth?

Science Journals – 3-25-14

1. Alpha Centauri A at 4.3 lightyears (closest to Earth)

2. Sirius B at 8.1 lightyears3. Luyten 726-8A at 8.7 lightyears4. Ross 154 at 9.7 lightyears5. Procyon A at 11.4 lightyears (farthest from

Earth)

WEATHER REPORT

The LIGHT-YEAR

• A light-year is a measure of distance. It is not a measure of time.

• A light-year is the distance that light travels in one year.

• It is equal to about 6 trillion miles.• 6,000,000,000,000 miles.

It’s A Great Big Universe!

Let’s See What’s Out There…

TEKS 8.8 A The student is expected to describe components of the universe, including stars, nebulae and galaxies, and use models such as the Hertzbprung-Russell diagram for classification.

Fabulous Fact or Mystical Myth

Stars have always “been there”MYTH! Stars are born from a cloud of gas

and dust called nebula.

Fabulous Fact or Mystical Myth

Galaxies are all the same.MYTH! Galaxies are classified by

their shape.

Lesson Objectives1. Students will understand what is in the

universe.2. Students will be able to describe stars

and their life cycle, from nebulae to dwarf stars and black holes.

3. Students will be able to classify stars via the HR Diagram.

4. Students will be able to describe the components of a galaxy and the three types of galaxies: elliptical, spiral and irregular.

Engage

Show video clip:First 3 Minutes of “Contact”

• What’s past our solar system? • How many stars do you think are out there? • How far do you think they are from Earth?

From each other?.• Why did the sounds get more quiet the

further away we got from Earth• How far out do you think we traveled?

ExploreActivity: Universal Concentration

• What will you find in the universe?• How old is the universe?• Are we alone?

www.spacetelescope.org

www.astronomyonline.org

Star

A self-luminous celestial body consisting of amass of gas held together by its own gravity inwhich the energy is generated by nuclearreactions in its interior

The “Discovery” of GalaxiesAt the beginning of the 20th century, what we now

call spiral galaxies were referred to as “spiral nebulae” and most astronomers believed them to

be clouds of gas and stars associated with our own Milky Way. The breakthrough came in 1924 when

Edwin Hubble was able to measure the distance to the “Great Nebula in Andromeda” (M 31, at right) and found its distance to be much larger than the diameter of the Milky Way. This meant that M 31,

and by extension other spiral nebulae, were galaxies in their own right, comparable to or even

larger than the Milky Way.

Edwin P. Hubble (1889-1953)

(NOAO/AURA Photo)

Types of Galaxies I. SpiralsSpiral galaxies are so-named because of the graceful

shapes of arms emanating from a bright central nucleus. Spirals are classified according to how

tightly or loosely wound the arms are, and it turns out that the brightness of the central nucleus is

correlated to the tightness of the arm. The galaxies M 104 (below) and M 51 (right) respectively show

tightly and loosely wounds. Notice the effects of dust in both galaxies. (NOAO/AURA Photos)

Types of Galaxies II. EllipticalsElliptical galaxies lack spiral arms and dust

and contain stars that are generally identified as being old. The elliptical galaxies M 32 (below) and M 110 (right) show varying

degrees of ellipticity. (NOAO/AURA Photos)

Types of Galaxies III. Irregulars

Irregular galaxies lack any specific form and contain stars, gas and dust

generally associated with a youth. The irregular galaxy at right is the

Large Magellanic Cloud, a satellite of the Milky Way located about 180,000

light years from the sun. The LMC is about 60,000 light years across. The bright reddish feature in the upper

right is the “Tarantula Nebula” a region of star formation in the LMC.

(NOAO/AURA Photo)

Galaxies in CollisionIn this close encounter between two spiral galaxies, their arms are dramatically warped and massive star formation is triggered when the hydrogen gas clouds in the two collide. It is believed the Milky

Way may have “cannibalized” small galaxies in the past through collision.

Hubble Space Telescope Image

ExploreActivity: Name That Galaxy!• Galaxies are classified by shape.• The shapes are irregular, spiral &

elliptical.• What do you think a galaxy with that

shape would look like?

www.waidobservatory.com

Life Cycles

ExploreActivity: A Star’s Life • Are all stars “born” the same way?• Do all stars “die” the same way?• How is a star’s life cycle similar to a

human life cycle?

www.spacete

lescope.org

www.universetoday.com

ExplainWhat is the universe? All that is in existence.

What’s in the universe? Galaxies, stars, gases, planets, dust, other matter.

What is a galaxy? Collection of stars, dust, and gases held together by gravity. What’s our galaxy? The Milky Way

Is ours the only one? No. There are billions of galaxies in the universe.

What is in a galaxy? Stars, gases, planets, asteroids, comets, etc.

ExplainHow do scientists classify galaxies? By shape. Elliptical is round/oval shaped, spirals are pinwheel shaped and irregular have no specific shape.

What are stars? Balls of luminous gases of various mass and temperature held together by gravity.

How do stars form? They are formed from compressed gas and dust found in nebulae.

Do all stars “die” the same way? Lower mass stars form small “dwarf” stars while larger mass stars can explode in a supernova. Some high mass supernova will form black holes.

Elaborate IActivity: Starlight, Starbright

Students will examine stars of different color, temperature and luminosity and plot them on an HR-Diagram, while observing patterns and trends in the placement.

Elaborate I Debriefing•What patterns did you notice when examining the stars’ colors?

•What patterns did you notice when examining the stars’ temperatures?

•What patterns did you notice when examining the stars’ luminosity?

•Why do you think the HR-Diagram is useful to scientists when it comes to classifying stars?

Evaluate• All that exists (matter and non-matter) make up the

__________________.• ___________________are collections of stars, gas & dust

held together by __________________.• Luminous balls of gas in space are called ___________.• Stars are created from clouds of gas and dust

called___________.• Stars in the middle of their lifespan are called

________________.• As stars age, their color changes and their

temperatures_________.• A violent explosion of a high mass star at the end of its life is

called a ________________________________.• Galaxies are classified by _____________.• The three types of galaxies are ________________,

___________________, and _______________.