Study Guide for Exam 3 AST Steps to testing an observation Observation Hypothesis Prediction Test A scientific theory must make testable predictions Key Everything highlighted in yellow is a quiz question Science Units Meter measures distance Most modern telescopes are reflectors Modern telescopes are generally either located on mountains or in space because Second measures time Constellations The human tendency to find patterns where none exist Telescopes there is less atmosphere to see through Earth s tilt Earth s axis is actually tilted with respect to the plane of its orbit Earth s tilt causes it s seasons Kepler Kepler s First Law The orbital paths of planets are elliptical with the Sun at one focus Any given point on the ellipse has the same sum of the distance from each focus the major diameter Kepler s Second Law While orbiting the Sun an imaginary line connecting Sun and planet sweeps out equal areas of the ellipse in equal intervals of time Kepler s Third Law The square of a planet s orbital period is proportional to the cube of its semi major axis P 2 a 3 where P is years and a is in A U Orbital period time taken to traverse the full elliptical orbit Perihelion point of closest approach to the sun a 1 e Aphelion point of greatest approach to the sun a 1 e Semi Major Axis half the length of the long side of the ellipse Eccentricity distance between the foci divided by the length of the major axis A circle is just an ellipse with an eccentricity of zero Does not affect the period of mas of the planet Sun system at one focus Newton s First Law of Motion An object at rest remains at rest and a moving object continues to move forever in a straight line with constant speed unless some external force changes their state of motion Also known as Law of Inertia Newton s Second Law of Motion The acceleration of an object is directly proportional to the net applied force and inversely proportional to the object s mass Acceleration rate of change of velocity or speed Inversely proportional to mass the heavier the less you accelerate for the same force applied net force sum of forces acting on you Newton s Third Law of Motion To every action there is an equal and opposite reaction Universal gravitation 6 67 x 10 11 Nm 2 Kg 2 Diffraction limit The amount to which diffraction limits how well we can resolve objects depends on both the aperture of the telescope and the wavelength of the light Relates the peak radiated wavelength to the temperature Can calculate surface temperature of other planets using this law Shows the color and spectra Modified Kepler Law The orbit of a planet about the sun is an ellipse having the center Newton Diffraction Limit Wien s Law Earth s atmosphere is not transparent to all electromagnetic radiation Terrestrial Planets Facts on Terrestrial Planets Closest planets to the sun Venus is closest in size to Earth Made up of Mercury Venus Earth and Mars Venus and Earth are warmer than Mars and Mercury due to the greenhouse effect however the greenhouse effect takes place on Mars as well Carbon dioxide water vapor and methane are all green house gases Both Mars and Venus have atmospheres composed of mainly carbon dioxide Principle Processes Shape the Surfaces Impact cratering meteorite impacts rough up the surface Tectonism convection currents drive the tectonic plates against each other Volcanism eruption of hot material from the lower crust and upper mantle Erosion smooth s out surface topology by action of wind and water Jovian Planets Facts on Jovian Planets Jupiter Saturn Uranus and Neptune are all known as the Jovian Worlds Jupiter is the most massive of the Jovian planets They receive less energy from the sun compared to the terrestrial worlds as they are further away from the sun Have many rings and moons widely spaced orbits large radii and masses composed of mainly gas no solid surface low density fast rotation and strong magnetic fields They are large cold and massive We know less of Jovian worlds than we do terrestrial worlds because of how far away We only see the outermost parts of the Jovian worlds atmospheres which seem to look they are from the sun and us as well Uranus is the only Jovian planet that does not exhibit any internal heating Uranus has extreme seasons due to its tilt Each season winter and summer last 42 continuous years All have offset field lines less in Jupiter but very much so in Neptune and Uranus which is probably why Uranus has such extreme seasons Unlikely to find life in the Jovian worlds Their Atmosphere like cloud tops The cloud tops are where the atmosphere merges into a more condensed atmosphere and later and further along into the planet the atmosphere then merges into denser liquids or solid cores Cold at the cloud tops Chemically different clouds form at different levels in the Jovian worlds due to the difference in their condensation points Contain high temperatures This comes from the Jovian worlds continued collapse and liberation of gravitational energy However Saturn is exempt from this because on Saturn Helium sinks deep into the core depleting it from the atmosphere and enriching the core This liberates additional gravitational energy which is an example of differentiation What makes up Jovian Planets Made of larger less dense materials than terrestrial planets Jupiter and Saturn s compositions are similar to the sun s composition Uranus and Neptune are much more dense than Jupiter and Saturn and so their composition is nothing like the suns On the inside things are hot and dense Under enough pressure molecular hydrogen condenses into a metallic state known as metallic hydrogen Metallic hydrogen is when the electrons dissociate from protons in hydrogen under the right temperature and pressure This happens on Saturn less as Saturn has less pressure Not as sustained as the Great Red Spot On the surface of Neptune One of the most prominent features of Jupiter About the size of two Earths Methane causes Uranus and Neptune to appear blue Great Red Spot Will swallow up smaller storm systems Great Dark Spot Magnetosphere Rings Roche Limit Substantial magnetic fields of the Jovian worlds Jupiter has the king of magnetospheres Tells us what is going on in regard to the surface rotation of the planets All Jovian planets have rings except Saturn s are the most obvious Rings are unstable and some of their material may drift away or spiral into the atmosphere through collision Definition A distance from massive objects