Astronomy Detailed Exam 2025

What is a star? - -A star is a large luminous ball of gas that generates heat and light through nuclear fusion. What is a planet? - -A planet is a moderately large object that orbits a star. It shines by reflected light. Planets may be icy or rocky What is a moon? - -A moon (or satellite) is an object that orbits the planet. What is an asteroid? - -An asteroid is a small and ROCKY object that orbits a star. What is a comet? - -A comet is small and ICY object that orbits a star. What is the SOLAR SYSTEM? - -The solar system is a star and all of the material that orbits it; including it planets, moons and asteroids. Our Solar System is the Sun, Earth, Mars... What is a nebula? - -A nebula is an in stellar cloud of gas and or dust and it is indicative of star birth or star death. What is a galaxy? - -A galaxy is a great is a great island of stars in space, all held together by gravity orbiting the common center. An example: The Milky Way What is a Local Supercluster? - -A local supercluster is groups of galaxies that are typically clustered What is the definition of a Universe? - -The universe is the sum total of all matter and energy that is everything within and between all galaxies. What are the two elements that everything comes from since the Big Bang? - -The two elements are Hydrogen and Helium. H + He How big is a Light Year? - -a light year is 300 thousand kilometers per second or 300 million minutes per second. 3x10⁸ m/s About 10 trillion kilometers Astronomy Astronomy What is the equation for one light year and what does a light year measure? - -A light year equals the speed of light times one year. A light year measures distance. Powers of 10 - -10⁶ = 1,000,000 10⁰ = 1 10⁻¹ = 0.1 Powers of 10: Rule of Multiplication - -10^A x 10^B = 10^(A+B) Powers of 10: Rule of Division - -10^A / 10^B = 10^(A-B) The LARGE Scale Nomenclature - -Kilo = 1,000 = 10³ Mega = 1,000,000 =10⁶ Giga = 1,000,000,000 = 10⁹ Tera = 1,000,000,000,000 = 10¹² The SMALL Scale Nomenclature - -Milli = 0.001 = 10⁻³ Micro = 0.000001 = 10⁻⁶ Nano = 0. = 10⁻⁹ Pano = 0.000 = 10⁻¹² How Big Is The Universe? - -The universe is about 400 billion stars in the Milky Way. The Milky Way is one of about 100 billion galaxies There are as many stars as the amount of grains of sand. 10¹¹ stars times 10¹¹ galaxies equals about 10²² stars in the universe. What is the Cosmic Calendar? - -The cosmic calendar is a scale on which we compress the history of the universe into 1 year. For example: In a cosmic year, human existence in about a second. In what ways do humans employ scientific thinking? - -Scientific thinking is based on everyday ideas of observation and trial-and-error experiments. What are the dangers of common sense? - -Common sense often works well for humans and typically breaks down at the frontiers of science. For example, by saying the earth is not flat being compared to earth orbits the sun needs science to prove it. What are facts? - -Facts are sometimes referred to as empirical evidence and derived from experiments and they must be repeatable. Astronomy Astronomy What is a hypothesis? - -A hypothesis is an untested idea that can explain a phenomenon. What is a theory? - -A theory is a hypothesis which test have failed to disprove. It is not an undisputed facts. It's predictions must be correct. It can be disproved. What is Physical Law? - -Physical Law are theories that have become very well tested and are of fundamental importance. What is the Cosmological Principle? - -The Cosmological Principle: "There is nothing special about our place in the universe." More of The Cosmological Principle - -Our view from Earth isn't special or unique. On a large scale, the universe is the same everywhere. Matter and energy obey the same physical laws everywhere. We can learn about distant objects by studying nearby ones. All scientific knowledge is provisional. Scientific Theories must be able to be falsifies and rejected. This is how science progresses. Science's vulnerability is its great strength. Existing accepted ideas are subject to change from the scientific method; even idea accepted as the truth. What is Scienta? - -The word Scienta comes from the Latin word meaning knowledge. The Hallmarks of Science #1 - -Modern science seeks explanations for observed phenomenons that rely solely on natural causes. The Hallmarks of Science #2 - -Science progresses through the creation and testing of models of nature that explain the observation as simply as possible. For example: Occam's Razor = Simplicity Does Astrology have any scientific validity? - -Scientists tests have shown that serological prediction are no more accurate than we should expect from pure chance. For example: Horoscopes Motions in the sky: A day - -It is the rotation of the earth about its axis. The moon, our constant companion: a month - -The moon orbits around the earth. The reason for seasons: a year - -The earth orbits around the sun. Astronomy Astronomy Precision of the earth's axis: millennia - -a wobbling of the earths axis. What is the celestial equator? - -It is the extension of the earth equator onto the celestial sphere. The Milky Way - -If you see the the band of light across the sky. Our galaxy is shaped like a disk and our solar system is in that disk. Daily Motion: As the earth rotates - -The sky appears to us to rotate in the opposite direction. Daily Motion: The sky appears to rotate around the - -North or South celestial poles. Daily Motion: If you are standing at the poles - -nothing rises or sets (on a single night) Daily Motion: The altitude of the celestial pole - -Is your latitude. Daily Motion: Stars at an angle less than your latitude away from: - -your celestial