UNIT 1 - Astronomy Study Guide KEY

#1 - KNOW all of your vocabulary words. You will need know know these words in order to answer many of the questions on the test.

#2 - Know Earth’s place in our universe. Earth is part of a solar system. Our solar system is part of the Milky Way galaxy. Our galaxy is one of trillions in our universe.

#3 - What is the Big Bang Theory? The instantaneous expansion of space and time that marked the creation of our universe #4 – What is the name of our galaxy? The Milky Way

#5 - How was our solar system formed? Part of a nebula collapses in on itself A flat disk of spinning gas and dust forms Denser material collects in the disc’s center Nuclear fusion occurs and eventually a star is born Material left-over from star formation eventually clumps together and forms planets, moons, comets and asteroids

#6 - What is the shape of Earth and what does it cause? Earth is an oblate spheroid It is slightly squished down at the poles which causes it to bulge out at the equator

#7 - Understand the concepts of precession, nutation and barycenter. Precession – a 26,000 year cycle where Earth’s axis moves in a circle through space; causes the “north” star to change over time Nutation – an 18 year cycle caused by the pull of the Moon on the Earth; causes variations in Earth’s temperature Barycenter – the Sun moves around this point in order to stay in balance with the rest of the solar system

#8 - How many degrees is the tilt of Earth’s axis? #9 - What is the cause of Earth’s seasons and what is the relationship between the Sun and the Earth for each season? The tilt of the Earth and its position in its orbit around the Sun Northern hemisphere points towards the Sun in the summer, and away from the Sun in the winter.

#10 - Know Earth’s position relative to the Sun for each solstice and equinox. Know about when each of those happen. Summer Solstice – northern hemisphere is pointed towards the Sun; occurs around June 21st; Sun is directly over the Tropic of Cancer Fall (autumnal) Equinox – northern hemisphere is parallel to the Sun; occurs around September 21st; Sun is directly over the Equator Winter Solstice - northern hemisphere is pointed away from the Sun; occurs around December 21st; Sun is directly over the Tropic of Capricorn Spring (vernal) Equinox - northern hemisphere is parallel to the Sun; occurs around March 21st; Sun is directly over the Equator

#11 - Know all 8 phases of the Moon #11 - Know all 8 phases of the Moon. What they look like and what they’re called See drawing on board #12 - Know how the Sun, Earth and Moon interact to produce tides and eclipses.

#14 - Understand Kepler’s 2nd Law of Planetary Motion. #13 - Which early astronomer developed the three laws that describe how planets move through space? Kepler #14 - Understand Kepler’s 2nd Law of Planetary Motion. an imaginary line between a planet and the Sun covers the same amount of distance in the same amount of time A planet MUST go faster the closer it gets to its star and will slow down as it moves away from its star

#15 - Understand the difference between combustion and burning. Combustion = no flames = heat Burning = flames = light

Types of Energy Transfer Energy Production In the Sun #16 - Understand the three ways energy is transferred and how that relates to energy production in our Sun. Types of Energy Transfer Conduction – energy is transferred when particles touch each other (solids) Convection – energy is transferred through fluids (liquids and gasses) Radiation – energy is transferred by electromagnetic waves Energy Production In the Sun Nuclear FUSION – occurs in the core producing a photon Conduction – photon energy is passed from particle to particle Convection – energy rises to the surface by convection Radiation – energy is sent into space via electromagnetic radiation

#17 - Understand how solar forces remain in balance and how an unbalance in these forces leads to the death of a star. Thermal and radiation pressure try to push the star OUT Gravity tries to compress the star INWARD If pressure overcomes gravity, the star explodes If gravity overcomes pressure, the star implodes

#18 - How is the electromagnetic spectrum arranged and which wavelengths reach the surface of Earth? Arranged by wavelength and frequency RADIO MICRO IR VISIBLE UV X-RAY GAMMA largest wavelength smallest wavelength lowest frequency highest frequency ALL – visible light SOME – radio, micro, infrared, ultraviolet