Exam 2 Study Guide
Exam 2 Study Guide ASTR-1010-01
Popular in Solar System Astronomy
Popular in Art
This 6 page Study Guide was uploaded by Raven Hamilton on Friday March 25, 2016. The Study Guide belongs to ASTR-1010-01 at Clayton State University taught by Bram Boroson in Spring 2016. Since its upload, it has received 106 views. For similar materials see Solar System Astronomy in Art at Clayton State University.
Reviews for Exam 2 Study Guide
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
Date Created: 03/25/16
`Astronomy 1010 – Review for Exam 2 – in-class March 29 5: Light and Matter 6: Telescopes 7: Our Planetary System 8: Formation of the Solar System 9: Planetary Geology Review sessions: To be announced. Multiple choice with essay questions for extra credit. Closed-book, topics in bold are the most important Light and Matter What is a spectrum and how do we make one from light? What is the electromagnetic spectrum? Spectrum- a spectrum is a range of colors and waves that can be made by shining light through a prism. Electromagnetic spectrum- covers the entire range of wavelengths of light, including those that go beyond what the human eye can see. Includes, from shortest to longest wavelengths: gamma rays, x-rays, ultraviolet, visible waves, infrared, and radio waves. What is color, and what is the wavelength and frequency of light? How are wavelength and frequency related to the energy of a photon? What are emission lines and absorption lines and a thermal or continuous spectrum? How do we tell the temperature of a gas from its continuum spectrum? How do we learn what something is made of from its line spectrum? What happens to cause emission and absorption lines? What is the Doppler shift and what does it tell us? Color- depends on the intensity, mixture, absence, or presence of light. White light= all colors, Black= no light/no color. Light is made up of particles called photons, and the wavelength and frequency of light depends on that of these particles. The energy of a photon depends on its frequency. The speed of light can be found by multiplying wavelength by frequency. Emission lines- a thin or low-density cloud of gas that emits light only at specific wavelengths that depend on its composition and temperature, producing a spectrum with bright emission lines. Absorption lines- cloud of gas between observer and specific light source that can absorb light of specific wavelengths, leaving dark absorption lines in the spectrum. Thermal/ Continuous spectrum- spans all visible wavelengths without interruption We can tell the temperature of a gas from its continuum spectrum by measuring the thermal radiation. Thermal radiation depends on the temperature of the object, and the more light that shines from an object, the hotter that object is. We can tell the substance of an object using line spectrum because of chemical fingerprints held by each individual atom of an element. The spectrum allows us to identify these fingerprints and assess what an object is made of from them. Emission lines are caused by collision of atoms within a gas which causes the electrons in some atoms to gain energy and move to a higher energy level. These electrons, however, cannot remain at this higher level so they eventually fall back to the lower level. The energy that is lost when an electron falls to a lower level is emitted into a photon of light. Absorption lines are caused by the opposite of emission line spectrum. As the atoms move to higher energy levels they absorb photons in order to raise their electron levels. In summary, emission lines emit photons from loss of energy in electrons, while absorption lines absorb photons to raise electron levels. Doppler shift- The change in frequency of a wave for an observer moving relative to its source. The Doppler shift reveals the motion or speed of an object relative to our position. The terms red shift and blue shift apply to this concept. If an object is red shifted, meaning that on a spectrum the colors shift toward red, then the object is moving away. It is the opposite for blue shift. Stationary objects will have no shift and wavelengths displayed on the spectrum while neither shorten nor lengthen (shift blue or shift red). Blue shift= shorter wavelengths, red shift=longer wavelengths. Telescopes How is the opening of a telescope related to its light-gathering ability? What is resolution? How is resolution limited by a telescope’s opening and by the atmosphere? What is the diffraction limit? What are reflecting and refracting telescopes? Which kind is used more for the largest telescopes in the world? The opening of the lens (referred to as aperture) affects the amount of light able to be collected by the detector. The larger the opening, the more light and vice versa. Resolution- quality an accuracy of an image. Angular resolution is the smallest angle over we can distinctly distinguish between two objects. Resolution is adversely affected by the properties of light. Light is an electromagnetic wave, and separate light sources can interfere with one another, distorting the image. Larger telescopes are capable of greater resolution because there is less interference of this kind. Another aspect that adversely affects resolution is Earth’s atmosphere. Weather, daylight, light pollution, and atmospheric turbulence (wind movement) are the main causes of Earth bound interference. Diffraction limit-the angular resolution a telescope can achieve, being limited only by interference of light waves. Reflecting telescope- uses a curved primary mirror to gather light which is then reflected to a secondary mirror that lies in front of it. The light is then focused to a place where it can be observed. Refracting telescope- uses transparent glass lenses to collect and focus light The largest telescopes most commonly use reflecting lenses. Our Planetary System Overall, what is the Sun like and what are the planets like? What are Jovian and Terrestrial planets and how are they different? What are the major patterns in our solar system and what are some exceptions? How do we explore the solar system with flybys, orbiters, and landers? The Sun takes up 99% of mass in the solar system and is a large ball of gas made mostly of Hydrogen and Helium. Mercury, Venus, Earth, and Mars are terrestrial planets and Jupiter, Saturn, Uranus, and Neptune are Jovian planets. Mercury is made mostly of rock and metal with an iron core, the day and night temperatures are extreme (hot during the day, freezing at night). Venus is almost identical in size to the Earth, the surface is hidden under clouds, and the planet is extremely hot due to an extreme greenhouse effect. Earth is the only known planet with liquid water and life, and is the only terrestrial planet with a moon. Mars has no atmosphere, with giant volcanoes and craters and evidence of past presence of water. Jupiter has no solid surface and is made mostly of Hydrogen and Helium like the Sun. It is over 300 times the size of Earth and has many moons. Saturn is like Jupiter with rings of small particles of ice and rock and many moons. Uranus is smaller than Jupiter and Saturn, but composed of the same elements along with hydrogen compounds. It also has an extreme axis tilt, almost on its side. Neptune is the eighth and final planet in the solar system and is similar to Uranus with many moons. Jovian planets are the larger planets in the outside portion of the solar system that are composed entirely of gas (hydrogen, helium, and hydrogen compounds) and lack solid surfaces. Terrestrial planets are the four inner planets that have solid surfaces and are made mostly of rock. The moon is included in terrestrial planets. Patterns in the solar system: all planetary orbits are nearly circular and lie nearly in the same plane, all planets orbit the Sun in the same direction, counterclockwise as viewed from above Earth’s north pole, most planets rotate in the same direction with small axis tilts, and most of the moon’s in the solar system exhibit these same properties. Exceptions to these patterns include Earth being the only terrestrial planet with a moon and Uranus’ side titled axis. Flybys- as the name suggests, this mission involves spacecraft that only flyby a planet once, on a continuous journey through the solar system and beyond. Orbiters- mission includes flying to a destination and getting caught in the object’s gravity so that the spacecraft will be allowed to orbit the object and collect data over time. Landers/ probes- fly to destinations and land on them which allows the space craft to collect detailed information about the object. Formation of Our Solar System What is the nebular hypothesis? How does it explain the patterns in our solar system (tilt of planets, direction of their orbits)? What is the relation between the conservation of angular momentum and the formation of a disk of gas that became the planets? What might be the origin of the Moon? What is the frost line and why do we think Terrestrial and Jovian planets formed where they did? How did the solar system become clear of debris and how did the Sun reach its current rate of spin? Nebular hypothesis- originates from German philosopher, Immanuel Kant, and French mathematician, Pierre-Simon Laplace. States that the solar system formed from the gravitational collapse of an interstellar cloud of gas. Patterns in the solar system are caused by the collapse of the interstellar gas of the nebular hypothesis. The collapse of the gas and the process of that collapse are the origin of planets tilt and orbit direction. At some point, the rotation speed of this interstellar cloud increased as the cloud contracted; the same principles of angular momentum. The cloud shrunk and the speed increased, causing the set rotation speed of objects in the solar system today. The Moon is thought to have originated from debris from the collision of planetismal with the Earth. Frost line- the distance at which it was cold enough for ices to condense. The frost line marked key transition between the warmer region and the cooler region of the solar system. Terrestrial planets formed in the inner region because only rock and metal could condense in this warmer region. The outer region was ideal for the formation of the Jovian planets because of the abundance of hydrogen and the ability for it to condense into ices. The solar system was cleared of debris by a combination solar wind and radiation from the Sun. The Sun reached its current rate of spin by the transference of angular momentum during the clearing of the solar nebula. Support from this theory comes from observations of other stars. Planetary Geology What causes the layers inside a terrestrial planet? How do we know about the insides of terrestrial planets? What makes a planet's inside hot and how does it cool off? Which planets cool off faster? What causes a planet's magnetic field? Histories of planets: Highlands vs. maria on the Moon, Mercury shrank, Venus and volcanoes and repaving of the surface, Earth's tectonics, Mars and its large volcanoes and canyon, that it had water. The layers inside a terrestrial planet are caused by differentiation which is similar to the mixing of water with oil. Gravity pulls denser materials to the core while other substances “float” above in layers. Most of the knowledge about the interior of Earth come from seismic waves. These waves travel through the interior and along the surface after an earthquake and reveal clues about the composition of Earth. For other terrestrial planets looking at their density, volume, gravitational pull, and magnetic fields tells us about their compositions. Planetary interior heating is caused by three things: accretion, differentiation, and radioactive decay. Accretion is caused by colliding planetesimals that turn kinetic energy into thermal energy which is added to a planet. Differentiation is, as stated before, caused by movement of lighter and denser materials with a planet. The loss of gravitational potential energy that occurs during this is converted into thermal energy by friction. Radioactive decay is the main source of heating presently and is caused by the decaying of nuclei within a radioactive element. As the element decays subatomic particles collide with atoms and this energy is transferred into thermal energy. Planets cool off through convection, conduction, and radiation. Convection transfers heat upward, conduction transfers heat to cooler materials, and radiation (primarily infrared for planets) emits thermal energy into space. Smaller planets cool off faster. A planet’s magnetic field is caused by rapid rotation, and electrically charged core, and convection within layers. Formation of the Lunar Maria (Latin for seas): the early surface was covered with craters, there was a large impact that weakened the crust of the Moon, and heat built up and allowed lava to spill on the surface and as it cooled those areas became darker. Moon Highlands- crowded with craters upon craters caused by past collisions with other planetesimals. Tectonic evidence shows that Mercury has shrunk over time. Cliffs on Mercury show that tectonic forces compressed the crust, and Mercury’s large iron core gained a good amount of heat from accretion and differentiation which, as it cooled, caused the planet to contract in size. Venus shows evidence of volcanic flows with a variety of lava types. Volcanoes on Venus include shield volcanoes and stratovolcanoes. Tectonic stress has caused fracturing and contortion of the surface, while there is strong evidence of mantle convection beneath the lithosphere. Tectonics on Earth have caused what was once a large land mass, Pangea, to spread into several continents over billions of years. This is referred to as the continental drift. Plate tectonics has shaped a lot of the Earth’s surfaced, is still an ongoing force, and can be measured to determine past land locations on Earth.
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'