Star and Galaxies

Stars Galaxies and the Universe

Mrs. Dooley's 7th Grade Science

Stars

• A star is a large sphere of hydrogen gas hot enough for nuclear reactions to occur in it core.

• A star's core heats as gravity pulls gas inward, once its hot enough nuclear reactions begin and energy begins to travel outwards.

Open Ended

What is a star? Why do you think that stars exist? Now read together Light from stars.

Light from stars

When measuring distanced to stars astronomers use light speed instead of AU's.

One light year is equal to 9.6 trillion km.

Types of stars pg 374

• At first glance all stars appear white. But if you look closely you will see that some stars are red or orange and even may appear blue.

• Why is that? QP

• Lets continue reading!

Earth's Star-The Sun pg. 374

• The sun is the closest star to Earth.

• Scientists hypothesize that the sun has a lifetime of approximately 10 billion years, so it will continue to shine for 5 billion more years.

• What do you think will happen when the sun stops shining?

Galaxies

Read together page 375

Types of Galaxies

-elliptical

-irregular

-spiral

Galaxy (Cont.)

• a galaxy is a huge collection of stars gas and dust.

• The universe contains hundreds of galaxies

• VIDEO!! 6 Minutes

What are your thoughts on the video I just showed you?

Now read together page 376.

The Big Bang Theory

states that the universe began from one point and has been expanding and cooling ever since.

END OF LESSON

With your partners answer questions 1-5 and be prepared to give an answer to Mrs. Dooley