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Astronomy Notes Image From: http://www.astronomy-pictures.net/spiral_galaxy.jpg; 1 of 11 Stars • An object made of gas that gives off energy – mainly hydrogen – helium The Sun • • • • medium in size & life span compared to other stars primary energy source for all processes on Earth much closer to Earth than any other star! about 4 ½ billion years old H-R Diagram: Shows the relationship between color, temperature, magnitude & size of stars. Magnitude • Color = temperature • Magnitude = how bright • Our Sun is a main sequence star. 2 of 11 Black Dwarf Nebula 1. Large cloud of gas & dust where stars form. 2. Gravity pulls 4. Outer layers 5. Collapses material into a come off sphere that to just its 3. Expands becomes core dense, hot Explodes! & ignites. 3 of 11 4 of 11 Galaxy • A large grouping of stars in space. • 3 types 1. Spiral – bulge in center & distinctive spiral arms • • Example: Our galaxy, The Milky Way Our solar system is located within an arm 2. Elliptical – spherical or elongated 3. Irregular 1 2 3 Our Solar System 5 of 11 Terrestrial Planet: a rocky, INNER planet Mercury • closest to the sun • no atmosphere • full of craters • very hot during day; freezing cold at night Venus • Similar in size to Earth • Hot, thick & poisonous atmosphere Earth – home! Mars • known as the “red planet” because of its ironrich soil 6 of 11 Gas Giant: large, OUTER planet that is made mostly of gases Jupiter • largest planet • known for its storm, “The Great Red Spot” Saturn • known for its ring system Uranus • known for blue-green atmosphere Neptune • blue-green atmosphere like Uranus • Also has a storm, “The Great Dark Spot” Moon 7 of 11 • A natural satellite of a planet. • The outer planets have many of them! Image From: http://sos.noaa.gov/images/Solar_System/moon.jpg; Definition: www.thefreedictionary.com Other Rocky Bodies... Asteroids • asteroid belt between Mars & Jupiter • small, rocky body that revolves around the Sun Meteoroids – in space (like asteroids), but usually smaller Meteors – (meteor shower); a bright streak of light caused by the rock burning as it streaks through the atmosphere Meteorites – piece of rock that has landed on Earth without completely burning up, possibly making a crater Comet – a body of ice, rock and dust that forms a tail as it gets close to the Sun 8 of 11 Light Year A measure of how long it takes light to travel through space in one year. Image From: http://uniqhorns.com/images/milkyway.gif; Definition: www.thefreedictionary.com 9 of 11 10 of 11 Electromagnetic Spectrum The range of all the waves that can travel through matter as well as empty space. R O Y G B I V Scientists use different portions of the spectrum to learn about the universe. Ex: light waves can tell us what elements stars are made & if they are moving away or towards other objects. Image From: http://www.lcse.umn.edu/specs/labs/images/spectrum.gif Definition: www.thefreedictionary.com Theories on the Origin of the Universe 1. Steady State – has always been the same 2. Oscillating Model - began by expanding, has slowed down & is now contracting 3. Big Bang - *the dominant theory • 12 to 15 billion years ago • Universe began as a dense point that exploded • It rapidly expanded & began to cool down, forming stars, etc. • Evidence discovery of cosmic background radiation red shift in EM spectrum suggest it is still expanding 11 of 11