AIM: HOW DO STARS FORM? DO NOW: How many stars are in our Solar System? Homework:

What are stars?  Balls of gases that give off light & heat energy.  Most stars are made up of hydrogen & helium.

What is the closest star to the Earth? The Sun: One of billions of stars Avg. size (main sequence star) A million times greater volume than the earth

Why does the sun look big compared to other stars? Other stars are so far away that they look like points of light. There are huge distances between stars. We only have one star (the sun) in our solar system.

How are stars formed?  From a spinning cloud of gas & dust called a nebula. Continued spinning & gravity causes materials to squeeze together to form a protostar

What is the lifecycle of a star?  The temperature & pressure builds up due to nuclear reactions (fusion of hydrogen to helium) creating energy  The protostar becomes a star when it gives off light & heat.  A star will continue to go through stages as nuclear reactions continue.

The Lifecycle of a Star

What is the measure of a stars brightness called? MAGNITUDE! This depends upon its temperature, its size and its distance from the earth. The brightness of a star as seen from earth is its__________ brightness. The actual brightness of a star is its__________brightness. apparent absolute

LETS REVIEW… WHY DO STARS APPEAR SO SMALL? WHAT IS A SPINNING CLOUD OF GAS & DUST? WHAT 2 GASES MAKE UP MOST STARS? WHY IS THE SUN SO IMPORTANT? WHAT IS A MEASURE OF A STARS BRIGHTNESS CALLED? WHICH TYPE OF STAR IS HOTTER, A BLUE STAR OR RED STAR? (WHY DID YOU PICK YOUR ANSWER?)

AIM: What objects are located in our solar system? DO NOW: What are stars? Homework: Handout 16-1 & 16-9 Big 8 Review pgs due Thursday

What are the names of the planets that orbit the sun? 1. MercuryMy 2. VenusVery 3. EarthExcellent 4. MarsMother _____________________ 5. JupiterJust 6. SaturnServed 7. UranusUs 8. NeptuneNachos

What does the word “planet” mean? “Wanderer” because they change their positions among the stars

What are the sun & all the objects that orbit the sun called?

What other objects orbit the sun? 1. Asteroids – large groups of rocks between Mars & Jupiter (asteroid belt) 2. Comets – made of rock, ice, dust, & frozen gases that make up the 3 parts: The core (nucleus), coma (together = the head) & Tail 3. Meteoroids – pieces of rock & metal

What happens if a meteoroid enters into the earth’s atmosphere? It is called a Meteor, which will burn up due to friction from the earth’s atmosphere.  Also called a shooting star What are meteors that hit the earth’s surface? Meteorites

What are the rings around some of the planets? Small particles of rock or ice considered tiny satellites What are satellites? Object(s) that orbit a body in space Example: The moon

Do other planets have moons? Yes Saturn = the most Earth & Pluto have 1 Mercury & Venus = 0

What are 3 features on the moon’s surface? 1. Maria: meaning “seas” -Broad, flat plains 2. Highlands: mountains 3. Craters: round pits

Other Facts About the Moon: American astronauts landed July 20, 1969 It has no water or atmosphere & Has 1/6 th less gravitational pull than the earth

LETS REVIEW… What are the 4 inner planets? What are the outer planets? What does the word “planet” mean? What other objects orbit the sun? What is a satellite? What is another name for a shooting star? What have you learned about the moon?

AIM: How do planets orbit in space? DO NOW: What are the differences between Asteroids, Comets, & Meteoroids? Homework: Handout 16-2 & 16-3

Why do planets orbit the sun? Gravitational attraction between the sun & the planets keep them moving in curved elliptical orbits around the sun. The Earth’s orbit around the sun is a slightly oval ellipse

What is an ellipse? A flattened circle, or oval What is an orbit? The curved path of one object around another object in space

Because of its elliptical orbit, is the earth the same distance from the sun at all times of the year? Perihelion – the point in a planet’s orbit when it’s closest to the sun. (January) Aphelion - earth farthest from the sun (July)

What is orbital velocity? The speed at which a planet travels in its orbit Does each planet take the same amount of time to travel around the sun? No Each planet has its own orbital velocity

What does orbital velocity depend upon? The gravitational pull of the sun. As distance decreases gravitational pull increases

Does the earth have the same orbital velocity all year? Why? No It’s not always the same distance from the sun When does the earth have the greatest orbital velocity? During Perihelion

Which planets have the fastest orbital velocity? The inner planets

What causes the inward pull? Gravity from the sun What causes the curved path of an orbit? The combination of 2 motions: 1. A forward motion & 2. An inward pull

LETS REVIEW… Why do planets orbit the sun? What is the shape of the earth’s orbit? What happens to gravitational pull as distance increases? What causes the curved path of an orbit?

AIM: 1. How did the solar system form? 2. What is a galaxy? DO NOW: Why do planets orbit the sun? Homework: Study for Quiz Test on Astronomy on Friday Big 8 Review pgs due Tomorrow

How did the Solar System form? We only have theories to explain this.

What does the Nebula Theory state? A spinning cloud of hot gases called a nebula shrank to form the sun, planets, & objects in the solar system -It happened over a long period of time.

What does the Big Bang Theory state? The universe began with a giant explosion from a single point about 15 billion years ago. Matter & energy formed stars & galaxies, which continue to expand outward.

What is a galaxy? A large system of stars How are galaxies grouped? Based upon shape

What are characteristics of the 3 types of galaxies? 1. Spiral Galaxies: composed of a nucleus of bright stars & 2 or more arms that branch out. -3 out of 4 fall in this group 2. Elliptical Galaxies: almost round, or flat disks -small -oldest stars are found here

What are characteristics of the 3 types of galaxies? (continued…) 3.Irregular Galaxies: no definite shape -smallest & least common What is the name of our galaxy? The Milky Way –Spiral Galaxy

LETS REVIEW… Brainpop.com – Big Bang

Aim: 1. Take & Go over Quiz 2. Review: What do you know about Astronomy? Do Now: Prepare for Astronomy Quiz Homework: 1. Bring #2 Pencil 2. Study your notes for tomorrow’s Astronomy Exam

1.Name the 2 main gases that make up most stars. 2.What is a spinning ball of gas & dust that is drawn together by gravity called? 3.Which planet is presently furthest from the sun? 4.The sun & all the objects that orbit the sun is know as __________________. 5.3 features of the moon’s surface are Marias, highlands & ___________. Name ________________

6.The moon is a natural satellite that has (give a fraction) less the gravitational pull of the Earth. 7.During what month is the Earth experiencing perihelion? 8.What 2 motions cause the curved path of an objects orbit in space? 9.How are galaxies grouped? 10. A meteor is also know as ______________. Bonus: A group of stars that forms a pattern (or picture) in the sky is known as _____________.

Aim: Exam What do you know about Astronomy? Do Now: Prepare for Astronomy Exam Homework: Big 8 Review Book pgs 75-79