Astronomy Unit Test Review Sheet

Astronomy Unit Test Review Sheet 1. Describe how each of the following scientists contributed to Astronomy: a. Galileo- used a telescope to see craters, moons, etc b. Kepler- Laws of planetary motion, elliptical orbits c. Newton- gravity explains why objects fall to the earth and why planets orbit the sun d. Hubble- proved the existence of other galaxies; classified galaxies e. Copernicus- Sun centered universe -heliocentric f. Ptolemy- Earth centered universe- geocentric 2. What is the difference between a reflecting and a refracting telescope? What other types of telescopes do scientists use to gather information? Refracting uses a glass lens and a reflecting telescope uses mirrors. Scientists also use telescopes such as x-ray and UV telescopes to see invisible light. 3. What is a light year? Explain how it is used by scientists. A light year is the distance that light travels in one year. Scientists use it to measure the distance between objects in space. 4. Diagram the electromagnetic spectrum, include all forms of radiation. Which are most dangerous to humans? Gamma rays (shorter wavelengths) are the most dangerous because they have the most energy. 5. List the colors of stars in order from lowest temperature to highest temperature. Red, Orange, Yellow, White, Blue 6. What is another name for Polaris? Why was Polaris a useful navigation tool? Polaris is also known as the North Star. It was used as a navigation tool because it does not move very much throughout the night. 7. Why do stars appear to be moving in a circle around Polaris? Many stars seem to move around Polaris as the Earth rotates. 8. Why do we experience different seasons at some parts of the Earth? The earth receives either direct or indirect sunlight as it revolves around the sun on a tilt. 9. Diagram Earth as it revolves around the sun and label the seasons. 10. When does, the Northern Hemisphere receive the most direct rays from the sun? June (summer solstice) 11. What causes the phases of the moon? We see different phases of the moon because we see different portions of the sunlit side of the moon as it orbits the earth. 12. How long does it take for the moon to revolve around the Earth and repeat the same phase? It takes about a month for the moon to revolve around the earth. 13. Diagram and name the 8 phases of the moon, starting with a New Moon. 14. Explain why the oceans experience high and low tides on Earth. How many tides will an area on Earth experience each day? The earth experiences high tides when that part of the earth’s oceans is pulled outward by the moon’s gravity. The tides change from high to low (every 4 hrs) as the Earth rotates. There are 2 high and 2 low each day. 15. What are Spring Tides and Neap Tides? When do they occur? Include a diagram. Spring tides are the greatest tides because the moon and sun’s gravity combine. A neap tide is the lowest tide because the moon and sun are at right angles from each other. 16. What is a lunar eclipse? What is a solar eclipse? A lunar eclipse is when the moon is shielded by the shadow of the earth. A solar eclipse is when the sunlight reaching the earth is blocked by the moon. 17. How does the sun generate energy? Explain this process. Nuclear fusion generates energy as hydrogen atoms combine to form helium atoms. 18. What determines the lifecycle of a star? Explain why this is. The life of a star depends on the mass of the star. This will determine how hot it will burn and how stable it will be. 19. List the following types of stars from oldest to youngest: giant, supergiant, white dwarf, main sequence. Main sequence, giant/ supergiant, white dwarf 20. Draw an HR diagram with the x and y axis labeled and where the types of stars will be (main sequence, red giant, white dwarf, etc.) 21. Name and describe the 3 different types of galaxies? Spiral galaxies have concentrated centers and spiral arms. Elliptical galaxies have a concentrated circular or oval shape. Irregular galaxies have a shape unlike a spiral or elliptical galaxy. 22. What type of galaxy is the Milky Way galaxy? spiral 23. What is the Big Bang Theory? A theory about how the universe began after a big explosion. 24. What evidence can be used to support the Big Bang theory? Who is credited for this law? Hubble proved that the universe was expanding by showing that the light coming from it is red shifted or longer. 25. Explain how the solar system formed. Be detailed. Gravitational collapse of a part of a giant molecular cloud, most of the collapsing mass collected in the center, forming the Sun, while the rest flattened into a protoplanetary disk out of which the planets, moons, asteroids, and other small bodies formed. 26. What are the 4 main criteria used to identify a planet a. Orbit a star b. Be big enough that its own gravity causes it to be round c. Be small enough that it isn’t a star itself d. Have cleared the area of its orbit of smaller objects 27. Explain the following in terms of what it causes on the planet What does it cause/ Length on Earth Length on Length on create on (hours or days) Mercury Jupiter the planet Spins on its 24 hours 56.84 days 0.41 days Rotation: axis orbits the 365.24 days/ 1 0.24 years 11.86 years Revolution: sun year 28. Describe how the planets formed and include why the inner planets are so different in structure than the outer planets. Inner planets are rocky and small compared to the outer plants that are gas giants. The heat from the sun caused the inner planets gases like hydrogen and helium, to escape. 29. Define the following space objects: a. Asteroid: very small, irregularly shaped, rock bodies b. Meteor: in the earth’s atmosphere, forms a streak of light across the sky c. Meteoroid: small pieces of matter in outer space d. Meteorite: a meteor that has impacted Earth’s surface. e. Comet: small, icy objects that orbit the sun. 30. Describe the following regions of space: a. Asteroid Belt: The asteroid belt is the region of the Solar System located roughly between the orbits of the planets Mars and Jupiter occupied by several irregularly shaped bodies called asteroids. b. Kuiper Belt: A region of the solar system beyond the planets extending form the orbit of to the sun. c. Oort Cloud: is an extended shell of icy objects that exist in the outermost regions of the solar system.