Unit 2: Astronomy Earth Science- Ms. Gill Note Packet #3AName: ___________________________ Period: _____ Date:__________________

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A. What is Astronomy?Astronomy is the scientific study of matter in outer space, especially the positions, dimensions, distribution, motion, composition, energy, and evolution of

celestial objects and phenomena. (phenomena: is a hard to explain or almost magical occurrence)

B. There are many different Celestial Objects in our UniverseCelestial objects appear in the sky during day and night. They include:-The Sun -The Moon- Planets -Stars-Comets -Asteroids

-Meteorites -Black Holes

C. But where did these objects originate?-This Big Bang, which actually sounded more like a low hum, is estimated to have occurred between 12-15 billion years ago!!! -According to the Big Band Theory, all the matter in the universe started out as a single point! That point was extremely dense. It became unstable and exploded outward. -Today the universe continues to expand this is called Hubble’s Law – which states that nearby galaxies are moving away slowly while more distant galaxies are moving away more quickly.

Unit 2: Astronomy Earth Science- Ms. Gill Note Packet #3A

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D. The Universe is still expanding! Here is the proof!Scientists have two major pieces of evidence that support the Big Bang Theory.1) The Doppler Effect2) Cosmic Background Radiation

Figures A & B: Raisin bread analogy of the expanding universe

E. So what is the Doppler Effect?When an object is moving relative to an observer it distorts the way the observer perceives the object’s electromagnetic radiation. Whoa! What does that mean? Think about when an ambulance drives by, going very fast. The pitch of the siren changes as the ambulance approaches you and passes you. This is because the sound waves’ frequency is increased as it approaches you and decreased as it drives away. Visualize this concept using this diagram and the animation on my eboard.

In 1929, Edwin Hubble observed a similar phenomenon occurred with the light emitted from stars.

He discovered that if an object is moving toward earth it’s light shifted toward the blue end of the electromagnetic spectrum since the wavelength is “squeezed together” producing a shorter wavelength. This is called blue-shift! (Blue to You)

But if the object is moving away from earth, its light is shifted toward the red end of the spectrum, since the wavelength is “stretched out” making it longer. This is called Red-shift! (Red Away)

All galaxies show red-shift in their spectra, meaning they are moving away from us.

F. How big is the Universe?It is very humbling to contemplate the size of our Universe because it is unbelievably BIG and therefore it can make you feel VERY small. However it’s also impressive that our civilization has acquired such great knowledge, and it reminds us that we as people are a part of larger system. It is important for us to respect the natural equilibrium of our planet and the universe to whom it belongs. We must work to limit our environmental impact and continue to educate our peers about the delicate balance of this system.

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G. Measuring Distance: In order to grasp and describe the vast size of our Universe, we must first develop a measurement standard.

Distances between celestial objects are extremely large. Rather than miles, astronomers refer to a ____________________ as a

standard unit of distance. One light-year is the distance light travels in one year. The speed of light is 186,000 mps (300,000 kps). Thus, one light-year is about 6 trillion miles. The nearest star to us (Proxima Centauri) is 4.2 light-years away.

Astronomical unit: Another unit of distance is the _________________________ (AU). One AU is the distance from the Earth to the Sun (93 million miles) Distances to other objects are given in multiples of AU.

What is (approximately) the size of the solar system? ___________________________

Have you ever heard someone say that you’re seeing the past when you look up at the stars? It sounds romantic and perhaps even silly, but it is correct. For example, when an astronomer views the Andromeda galaxy, he/she is seeing how it was 2.5 million years ago. This is because it has taken that long for the light to reach us here, offering a window into the past that no history book ever could!

I. Components of our Universe.The best definition of the Universe is: EVERYTHING!We are all apart of the universe along with everything else you can think of.Outside of the edge of the universe is nothing. This is confusing because its hard to imagine “nothing”. The universe is expanding into nothing because nothing is in it’s way. All matter makes up the universe. I like to think of the components like a system of “Russian Dolls.” These components are organized from largest to smallest and they fit inside of each other:

The universe is made of billions of GalaxiesGalaxies are made of billons of StarsStars are the Center Solar SystemsSolar Systems are made of planets, moons, comets, asteroids and meteorites.Planets moons comet, asteroids and meteorites are made of matter.

H. Did you know…A light year is the distance light travels in a single year – 9,460,528,000,000 kilometers. So the light we see coming from Proxima Centauri left the star 4.2 years ago. Even being the nearest star, Proxima Centauri is incredibly far away. It would take our fastest spacecraft more than 50,000 years to make the journey.

Unit 2: Astronomy Earth Science- Ms. Gill Note Packet #3A

K. Billions of Stars make up a galaxy, but what is a Star… are they all the same?

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J. GalaxiesA ______________ is a collection of millions or billions of stars. Galaxies can be spiral, elliptical, spherical or irregular in shape. The Sun is part of the _________ galaxy, which is a spiral galaxy. The Sun is located on one of the spiral arms, far from the galactic center. When you look up on a clear night there is a hazy lighter band that runs across the sky. When you look at this band you are looking at the side of the spiral arm that is adjacent to the arm that our sun is in. Each arm is made of millions of stars. The stars themselves are too far away to see individually, but together their light combines to make the sky lighter in that area.

Must Know Facts about Star CharacteristicsA) A star is a huge, shining massive ball of gas in space that produces a large amount of light and energy. B) About 75% of stars are apart of groups that orbit each other. C) They are grouped in large structures called galaxies. (Milky Way).D) Stars have life-cycles like humans. E) A stars color depends on surface temperature.F) Stars vary in their size, mass, density, temperature and composition. G) ____________________ is the actual brightness of a star. H) Luminosity depends only a star’s _____________ and __________I) Most stars have planets that orbit them because of their immense gravity

Unit 2: Astronomy Earth Science- Ms. Gill Note Packet #3A

The Main Classifications of Stars:

____________________________ __________________________________________

Our Sun is classified as a____________________________________

The H-R DiagramThe Hertzsprung-Russell (H-R) Diagram on the rightis a graph of stars, comparing luminosity and temperature.

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Composition

Stars are primarily made of __________________ and Helium. Many other elements are present in stars in small amounts. A star’s composition can be determined by ___________________________.

Spectral Analysis_____________________ is the study of the electromagnetic spectrum emitted by a star, using a _______________________.

Each element in the star emits radiation is a specific set of ______________

Color and Temperature A Star’s color that we see with the naked eye depends upon its surface temperature. As materials become hotter, their color changes from:

Red to Orange to Yellow to White to Blue

What color are the stars in theConstellation Orion? (ESRT p 15)Betelgeuse is ________Rigel is ____________

How Do Stars Radiate Energy?A stars energy is the result of nuclear fusion, in which Hydrogen atoms combine to form Helium atoms, releasing energy. This Electromagnetic energy is radiated by stars.

Unit 2: Astronomy Earth Science- Ms. Gill Note Packet #3AStars are categorized according to these two properties!

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The H-R Diagram The Main Sequence is the band

into which most stars fall. They lie somewhere in between a:

High temperature, high luminosity&

Low temperature, low luminosity

Red Giants and Supergiants – cooler, very luminous stars that are very large

White Dwarfs are hotter, low luminosity stars that are small

Star Life Cycles Stars are born in a cloud of gas and

dust, called a _________________. Most stars remain as

______________________ stars, until their hydrogen fuel is depleted

An average star, like the sun, would go through the Red Giant phase, eventually becoming a _____________________.

A large star would become a ___________________, then explode as a supernova. The result may be a neutron star, pulsar or black hole.