Galaxies are huge collections of stars that form spiral structures. Our own solar system is in the Milky Way galaxy, and you can see it in the night sky if you are far away from city lights.

Course Competencies and Learning Objectives

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CC2.1 Analyze the science of stars and galaxies

LO2.1.1 Determine the origin of stars and their life cycle

LO2.1.2 Perform computations involving a star’s brightness, color, and temperature

★ LO2.1.3 Identify galaxy properties

★ LO2.1.4 Identify properties and predictions of the Big Bang theory

Readings

Read Chapter 14 (section 14.3) of Physical Science, 13^th edition by Bill Tillery McGraw Hill Education

Extra

NASA: Galaxy Evolution, Images of Galaxies

Media

Milky Way Galaxy

The following image is of the Milky Way galaxy and was taken by NASA's Spitzer Space Telescope's infrared cameras to penetrate much of the dust, revealing the stars of the crowded galactic center region. Because we are inside of this galaxy we see the cross section of the galaxy's disk, but when we look out side of our galaxy to view other galaxies we can then see their spiral shape. The bright dots you see are other stars in the Milky Way.

NASA's Spitzer Space Telescope's infrared cameras penetrate much of the dust, revealing the stars of the crowded galactic center region.

credit: NASA

Messier 81 Galaxy

The following galaxy is fairly close to our own (12 million miles away), and is known as the Messier 81, and is located in the northern constellation of Ursa Major (which also includes the Big Dipper). You should take not of its spiral arms. This image was taken by NASA's Spitzer Space Telescope.

Messier 81 image from NASA's Spitzer Space Telescope. Northern constellation of Ursa Major (which also includes the Big Dipper)

credit: NASA

Andromeda Galaxy

The following is an image from NASA's Wide-field Infrared Survey Explorer (WISE) of the Andromeda galaxy, which is the closest galactic body to use, and is 2.5 million miles away. The bright dots you see in the spiral are stars in the Andromeda galaxy, and the bright blue dots you see in the background are other galaxies.

credit: NASA

Mini Lecture - Light Year (Speed of Light)

This video explore how vast space is, and that it is so big, and everything is so far spread out, that it even takes light a very long time to traverse it.

Time: 4:48

ASL version of Light Year (Speed of Light)

Direct link to the non-ASl version

Mini Lecture - Oblers Paradox (Space Between Stars)

Time: 5:27

ASL Version of Obler's Paradox (Space Between Stars)

Direct Link to Video

Evidence for the Big Bang

In this video you will learn about the evidence for the Big Bang.

Time: 12:34

ASL version of Why the Big Bang Definitely Happened

Channel: PBS Space Time

Cosmic Microwave Background Explained

CMB Radiation is left over radiation from the annihilate of matter and antimatter in the early universe. For example, an electron and a positron annihilate each other, and to conserve energy and momentum two photons are produced. Photons are particles of light, and the amount of energy they have determine what type of light they are. These two photons are gamma rays. Over billions of years, the universe expands, and these gamma rays elongate becoming what they are today: microwaves.

Time: 7:09

ASL Version of Cosmic Microwave Background Explained

Channel: PBS Space Time

Practice and Apply

You can use these questions to test yourself on what you have learned.

PROMPT What is the nearest similar galaxy to ours.

Answer

Andromeda Galaxy

PROMPT What evidence do those that hold to the Big Bang Theory point to in support of their theory?

Answer

data about expansion of the universe
relative abundance of the elements formed in the core of older stars
analysis of cosmic microwave radiation