Vastness of the Universe ESSENTIAL QUESTIONS: . 1. What makes up the universe?  2. What is the hierarchal relationships between galaxies, planets, solar systems, universe, and stars? (list from largest to smallest) Objectives: Describe the distances between objects in both the solar system and universe. Explain why the light we see from a star may be hundreds of years old when it reaches Earth.

Observable Universe https://www.youtube.com/watch?v=HiN6Ag5-DrU

Bellringer The light from many stars can be seen from Earth. But there is a time delay between the time the light is emitted from the star and when we see it here on Earth. Which of the following statements best explains why there is a delay? Stars twinkle, so they give off light at regular intervals. The stars’ light is not bright enough to reach Earth immediately. Stars are light-years away from Earth, so light takes time to reach our planet. Earth’s atmosphere is too thick for light to reach the surface as soon as it is emitted.

Nebulae and Stars Nebulae are clouds of dust and gas where stars form Stars are giant spheres of flaming gas undergoing nuclear fusion.

The Planets The Rules to be considered a planet: A planet must be shaped like a sphere. It must orbit the sun. It must have enough gravity to have a clear orbit (nothing in its way).

Our Solar System The solar system contains our Sun, which is a star. In addition, eight major planets and their moons, “dwarf” planets, and countless asteroids, meteoroids, and comets.

What is a “galaxy”? A galaxy consists of hundreds of billions of stars, planets, and other celestial bodies held together by gravity. Information at http://hubblesite.org/newscenter/archive/releases/galaxy/spiral/2007/41/results/50/ NOVEMBER 29, 2007: Resembling festive lights on a holiday wreath, this NASA/ESA Hubble Space Telescope image of the nearby spiral galaxy M74 is an iconic reminder of the impending season. Bright knots of glowing gas light up the spiral arms, indicating a rich environment of star formation. M74 is located roughly 32 million light-years away in the direction of the constellation Pisces, the Fish. The image is a composite of Advanced Camera for Surveys data taken in 2003 and 2005.

Our Galaxy: The Milky Way The Milky Way is our galaxy which contains the Solar System.

The Universe Consists of everything that exists, including all matter and energy, the planets, stars, solar systems and galaxies. Each of those little dots aren't stars… They're galaxies (with billions of stars in each)

Astronomical Units An astronomical unit (AU) is the average distance from the Sun to the Earth, or about 93 million miles. Used to measure distances inside our solar system. We use AU when discussing distances from the planets to the sun.

Light-Years A light-year is a unit of distance. It is the distance that light can travel in one year. (About 6 trillion miles) Used to measure distances OUTSIDE of our solar system. We use light-years when discussing distances within intergalactic space. (2 or more galaxies)

Light-Years  It takes light between 100,000 years and 50 million years to escape and travel through space. From our vantage point here on Earth we can see light from stars that are thousands to millions of light-years away. We use light-years when discussing distances within intergalactic space. (2 or more galaxies)

How Big is the Universe? https://www.youtube.com/watch?v=1Eh5BpSnBBw

REVISITING THE Bellringer The light from many stars can be seen from Earth. But there is a time delay between the time the light is emitted from the star and when we see it here on Earth. Which of the following statements best explains why there is a delay? Stars twinkle, so they give off light at regular intervals. The stars’ light is not bright enough to reach Earth immediately. Stars are light-years away from Earth, so light takes time to reach our planet.* Earth’s atmosphere is too thick for light to reach the surface as soon as it is emitted.

You DO Time!

YOU DO Question #1 Use the table that lists the distances of astronomical bodies from our Sun to help you answer the following question: Using our current space travel technology, which astronomical body would we be MOST LIKELY to visit first during your lifetime? Charon Proxima Centauri Vesta Wolf 359 Astronomical body Distance from the Sun Charon (dwarf planet) 40 astronomical units (AU) Proxima Centauri (star) 4.2 light years Vesta (asteroid) 2.5 astronomical units (AU) Wolf 359 (star) 7.8 light years Correct Answer: C

YOU DO Question #2 Jeannie reads that light from the North Star, called Polaris takes 434 years to reach us on Earth. Why does it take the light from Polaris so long to reach us on Earth? Most of the light from Polaris is absorbed by different objects in space. Light from Polaris travels a vast distance before it reaches Earth. It is difficult for light to pass through the Earth’s atmosphere. Light slows down as it travels through space. Correct Answer: B

YOU DO Question #3 Antonio is attempting to sketch all of the stars in the Milky Way galaxy for science class. His friend comments that it will not be possible to create an accurate sketch. Why is a sketch NOT appropriate for representing all of the stars in the Milky Way? The Milky Way contains a black hole at the center, which he cannot accurately represent Antonio needs to use a three dimensional model in order to represent the stars The Milky Way contains billions of stars, which he cannot show using a sketch Antonio needs to graph all of the stars in a diagram based on their luminosity Correct Answer: C

EXIT TICKET (Closing): What is the structure of objects in the universe and how does light help us understand the vast distances between them?