Chapter 7 Review (Pages )

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1 Chapter 7 Review (Pages ) Celestial is a term that refers to the sky. Objects we can see in the sky are called celestial objects. The Sun, the Moon, Earth, other planets, and comets are all examples of celestial objects. Astronomy is the study of the universe and the objects in it. An astronomer is a person who studies astronomy. At one time, astronomers had only two aids to help them understand celestial activity: sharp eyesight and a practical knowledge of mathematics. The solar system is the Sun together with all the planets and other celestial objects that are held by the Sun s gravitational attraction and orbit around it. At the centre of the solar system is the Sun, which is a star. A star shines because nuclear fusion is taking place at its core. Nuclear fusion is the process in which the nuclei of atoms fuse together and form larger atoms. During this process, an enormous amount of energy is released. One astronomical unit (AU) equals the average distance between the Sun and Earth, about 150 million km. For example, the planet Mercury is 0.39 AU from the Sun. This value is less than 1 AU because Mercury is closer to the Sun than Earth is. Mars One light year (ly) equals the distance that a beam of light can travel through space in 1 year. It is equivalent to AU or 9000 billion km. At the speed of light, you could travel around Earth seven times in 1 s. A trip from the Sun to Neptune at the speed of light takes about 5 h Out past Mars, we encounter the asteroid belt, a region of rocky debris that forms a ring all the way around the Sun at a distance of about 3 AU. The asteroid belt contains billions of pieces of rock of all sizes. Some of these chunks are smaller than a grain of sand. Others are huge. Our galaxy is about ly in diameter and about 2000 ly thick at its widest point, near the core. All galaxies contain stars, planets, and dust. Galaxies with more dust than others tend to produce more new stars, because stars form from dust and gases present in nebulae. Some galaxies, thought to be very ancient, have almost no dust because it has all been used up in star making. We cannot see the entire Milky Way directly because the solar system is inside it. However, if we could, it would look something like the collection of stars in the Pinwheel galaxy. A galaxy with this shape is known as a spiral galaxy. *Match Up on back*

2 Chapter 8 Review (Pages ) A constellation is a group of stars that, from Earth, resembles a recognizable form. Smaller recognizable star patterns within a larger constellation are known as asterisms. The best known asterism in the northern hemisphere is perhaps the Big Dipper, which is part of a larger constellation known as Ursa Major. A star is a huge ball of hot gas, or plasma. All stars form inside a collapsed nebula, a cloud of dust and gases. Inside a collapsed nebula, the area with the most amount of matter will start to draw material towards it, while material falling inward to the core has excess energy which causes the central ball of material to begin to spin. A protostar is then formed when extremely high pressures build up inside the ball and the core begins to glow. When the temperature of a spinning protostar is hot enough for nuclear reactions to start, the energy from its core reaches the star s outside and begins to shine. Low Mass stars burn their nuclear fuel much more slowly than bigger stars, so slowly that they can last for 100 billion years. With less gravity and lower pressures than other stars, the nuclear reaction in their core happen at a slow rate. These stars therefore exist a long time, shining weakly as small red stars called red dwarfs. Medium Mass stars burn their fuel faster than low mass stars do, using their hydrogen up in 10 billion years. At the end of this long period, the hydrogen fuel inside begins to run out and the star slowly collapses under its own gravity. The star reignites and as the core heats up this time, the star rapidly expands into a red giant. When their helium fuel burns out, both Low and Medium Mass stars start to dim and turn into smaller white dwarfs. Over time, after a white dwarf dies out, they become black dwarfs. High Mass stars have a mass that is 10 time greater than the mass of the Sun. As gravity pulls matter into the centre of the star and squeezes the core, the nuclear reactions accelerate. As a result, this star is hotter and brighter than other stars and always comes to a violent end. When heating and compression cause helium to begin to fuse, tremendously high temperatures result, causing the star to expand into a supergiant. When a High Mass stars has no helium fuel left to produce energy, the star collapses one last time. Its collapse is so intense that the core of the star heats up to millions of degrees and explodes, creating a supernova. The star s remaining core after a supernova explosion faces one of two outcomes; Neutron stars or Black holes. The Hertzsprung Russell Diagram shows the life cycle of stars and all their different varieties. The differences between them include what colour they are, how luminous they are, and what their surface temperature is. Tides are alternate rising and falling of the level of the oceans every day. They are caused by the rotation of Earth in the presence of the Moon and sometimes the Sun. The gravitational pull of the Moon and Sun on Earth s oceans and Earth itself causes the water bodies to bulge. As the oceans rise higher in one part, they fall in another. The pattern then reverses. *Crossword on back*

3 Chapter 9 Review (Pages ) Into The Frontier of Space 1972: Pioneer 10 was launched by NASA. The mission was to fly past Jupiter and explore what was beyond it. Back then people have never seen what was beyond it. 1973: Pioneer 11 was launched for a similar mission, but also to capture images 1977: Voyager 1 & Voyager 2 were launched to continue the study of the outer planets. On each Pioneer probe there is an engraved plaque showing a man and a women and other information on where the Earth is located. Aboard each Voyager probe is a golden record with recorded sounds and pictures of Earth. Important Dates On Earth Summer Solstice: Occurring June 21, the longest period of daylight in the year, and represents the start of summer. Winter Solstice: Occurring December 21, marks the shortest day of the year and represents the start of winter. Equinox: A day when the hours of daylight and hours of night are of equal length. The spring equinox occurs about March 21. The autumnal equinox occurs about September 22. Ancient civilizations used these events to mark timing. Models of Planetary Motion Geocentric Model: Model developed by early scientists such as Greek astronomer Ptolemy in the second century. A geocentric model is where everything rotates around Earth. The model was helpful at predicting moon phases, but it was also confusing. Mars, Jupiter and Saturn appeared to be looping backwards a few months in their route across the sky. This is called retrograde motion. Heliocentric Model: Model developed by Nicholas Copernicus, with the idea that the Sun was the centre of the universe and the Earth and other planets orbited around it. Two key things about planetary orbits proved the heliocentric model; The relationship between a planet's orbital radius and the speed of the orbit; and the other ones were that planetary orbits were elliptical. KEY THING #1 Orbital Radius: A planet's distance from the sun is called the orbital radius.the farther an object is from the sun, the weaker is the effect of the sun's gravity on that object making the orbital times different for each planet. Explains why Mars, Jupiter and Saturn display retrograde motion. Guess why? KEY THING #2 A german mathematician, Johannes Kepler observed the movements of the planets and discovered that the orbits of planets were not circles: they were ellipses. Today the heliocentric model is used rather than the geocentric model.

4 Evolution Of Astronomer's Tools Ancient Egyptians invented a device called merkhet: chart astronomical positions and predict movement of stars. Arabian astronomers used astrolabes. 14 century: astronomer Levi ben Gerson invented the cross staff to measure the angle between the moon and any give star. 16th century: The first telescopes were invented. There are 3 kinds of telescopes: Ground based Optical Telescopes (ground based telescope) Space based optical telescopes (located in space) Radio Telescope (study radio waves to find galaxies, nebulae etc.) Benefits Of Space Research Earthrise: Picture of what the Earth looked like from outer space. This image made people realize that our planet does not have infinite resources and that even the seas and the atmosphere are finite. Space Transportation Technologies: 1. Rockets life small capsules. 2. Space shuttles transport personnel and equipment to orbiting spacecraft. 3. Space Stations Orbiting spaceship that have living places. 4. Space Probes COntains instrumentation for carrying out robotic exploration of space. *International Space Station 1998, 400 km above Earth, largest spacecraft ever built.* Product Technologies: Many items, materials and systems first created for a space application have been put to practical use on Earth. Examples: Dehydrated food, Miniature computers, Scratch resistant plastic coatings, memory foam, antibacterial water filter, Infrared thermometer etc. Satellite Technologies: Artificial Satellite: A device placed in orbit around Earth or another celestial object. First satellite was launched in 1957 by the Soviet Union. Canada was the third country in the world to launch a satellite. A geostationary orbit is one in which a satellite orbits Earth at the same rate as Earth rotates. GPS relies on satellites Disadvantages Of Space Research and Exploration Hazardous Expensive Challenges of Physical Environment Microgravity: the condition in which the gravitational forces is often likened to feeling of weightlessness Challenges of confined living.

5 2/1/2015 Whats Up With Galaxies and Our Universe Whats Up With Galaxies and Our Universe 1. Black hole a. planet with methane in its atmosphere that gives the planet a blue colour 2. Dark matter b. galaxies without a definite shape c. central bar shaped structure composed of stars. Bars are found in approximately two thirds of all spiral 3. Star clusters galaxies 4. Spiral Galaxies d. distance that a beam of light can travel through space in 1 year 5. Barred Spiral Galaxies e. galaxies with an ellipsoid shape (flattened sphere) 6. Elliptical Galaxies f. similar to the planet Uranus, has the fastest wind speeds in the solar system 7. Irregular Galaxies g. rainbow band of colours into which white light separates when it passes through a prism h. when the universe was formed by an infinitely dense point suddenly and rapidly expanded in a single 8. Visible light spectrum moment 9. Big Bang Theory i. Planet mainly composed of hydrogen and helium, has three thin rings Electromagnetic j. average distance between the Sun and Earth, about 150 million km 10. radiation 11. spectroscope k. closest planet to the Sun, looks like the Moon 12. Spectral shifting l. matter in the universe that is invisible because it does not interact with light or any other kind of radiation 13. Nuclear fusion m. concentration of stars in a relatively small region of space AU n. 2nd closest planet to Earth and almost looks like it, though has a very high surface temp ly o. region of space where gravity is so strong that nothing, not even light, can escape 16. Mercury p. closest planet to Earth, a.k.a the 'Red Planet' 17. Venus q. the process in which the nuclei of atoms fuse together and form larger atoms 18. Mars r. optical instrument that, like a prism, separates light into its spectral colours 19. Jupiter s. second largest planet and has the most distinct ring system 20. Saturn t. Energy that travels in waves 21. Uranus u. change in position of spectral lines to the left or the right of where they normally are 22. Neptune v. galaxies with spiral shaped arms the radiate outwards your own/match up/match up worksheet.php 1/1

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