Home > Flashcards > Astronomy > Exam 1

Details Title: Exam 1 Description: Flash Cards for Exam 1 chapters 1-6 Total Flash Cards: 37 Created: 02/09/2008 10:32:10	To study from this set of flash cards, or to create your own your own study flash cards, register HERE. If you are already a registered user, CLICK HERE.
Cards Term           Astronomy  Definition Study of the heavens     Term          Modern Astronomy and Cosmology  Definition Study of the entire universe using scientific instruments, methods and simulations Term        Distance from the sun to the earth Definition 150 million km   1.5 x 10^11   = 93 million miles  Term         Astronomical Unit Definition 3 x 10^ 8 Term         Light Year  Definition 9.46 x 10^8 meters Term         "The Great Attraction"  Definition A group of superclusters in which our cluster is a part of Term         Dark Matter  Definition Motion of the stars in galaxies suggesting that there is an additional gravitational force due to a large amount of unseen matter   What we see may be as little at 10% of total  Term       Dark energy  Definition Rate of expansion of the universe that seems to be increasing as if it were pushed outward by some unknown sources of energy Term  1)Prehistoric (<500 B.C.) 2)Classical (500 B.C. - 1400 A.D.) 3)Renaissance (400-1650) 4)Modern (After 1650        Definition 1) Obscene motion of stars and planets. Learned to keep time 2)  Measurements of planetary motion made construction of simple geometrical models for motion 3) Telescope leading to mroe sophisticated models 4) Earth considered creator of the universe.  All stars attached to a "Celestial Sphere"  Term         Perception  Definition  All celestial objects (stars, planets, sun, moo) moved as if attached to the celestial sphere       Term         Motion around the Celestial Sphere  Definition Earth takes approximated 365 days each year to revolve around the sun   Tilt of earths axis 23.5 degrees causes seasons    June - Summer solstice March, Summer - Equinox December - Winter Solstice  Term         Zodiacs  Definition Determined by the time spent in front of a particular constellation Term         Who invented the telescope?  Definition Johannes Lippershey, dutch spectacle maker   Galileo took idea from Lippershey  Term         Importance of telescope  Definition 1) Magnify Images 2) Gather lots of light and see faint objects  Term       Sir Isaac Newton 1643-1727 Cambridge University  Definition Considered most influential person in the history of physics   Founding father of planetary motion  Term         Newtons 1st Law  Definition The Law of Inertia   A body continues in a state of rest, or motion in a straight line at constant speed, unless a force is applied to it  Term       Newtons Second Law Motion  Definition An object is said to be in uniform motion if its speed and direction remain unchanged   Has constant velocity   Force will cause it to have non-uniform motion (chanigng velocity)   Acceleration - change in velocity  Term         Newtons 2nd Law Acceleration  Definition An object increasing or decreasing in speed along a straight line is accelerating   Constant speed moving in a circle is accelerating   Produced by a force and the two are proportional (i.e. forces)    Measured in meters/second^2 (m/s^2)  Term       Newtons Second Law Mass  Definition Amount of matter an object contains   Measure of an objects inertia   Never changes  Term         Newtons Second Law of Motion  Definition F = ma   Amount of acceleration (a) that an object undergoes is proportional to the force applied(F) and inversely proportional to the mass (m) of the object    Measured in kilograms (kg)  Term         Newtons Third Law of Motion  Definition When two objects interact, they create equal and opposite forces on each other  Term         Newtons Law of Universal Gravity  Definition Everything attracts everything else   G (gravitational constant) = 6.67 x 10^-11 Nm^2/kg^2  Term         Weight  Definition Force related to gravity Term         Escape Velocity  Definition To be able to escape into space from a celestial object, mass must obtain a critical speed called "escape velocity"   Escape velocity of moon = 2.4km/s of earth = 11km/s    Determined by:  Vesc = 26M/R)^1/2  Term         Photoelectric Effect (Einstein)  Definition Light of a specific energy strikes solid surfaces, only electrons of a specific energy is ejected.  Term         Planck's Constant  Definition h = 6.63 x 10^-34 Nms(Newton meter seconds) Term         Types of Telescopes (2)  Definition Refractor - light bent by lenses Reflector - light bent using mirrors  Term       Refraction  Definition Changing of the direction of a beam of light as it enters a new medium   For example - entering water, lenses, atmosphere  Term         Keck Telescopes  Definition Largest visible telescopes   Keck twin- 10 meter, multi-mirror telescopes in Hawaii  Term         Resolving Power  Definition How big must a telescope be to see two objects individually Term         The Crab Nebula  Definition One of the first recorded astronomical objects Term        Advantages of space based/ground based telescopes Definition Ground - Increased collecting power, equipment easily fixed   Space - freddom from atmospheric blurring/absorption  Term         Earth  Definition Radius = 6,400 km Bulges at equator due to rotation Crest = Oxygen 45% and Silicon 27%   Core 6,400 K = 110,000 degrees F   Small S/V ratio  Term         Plate Tectonics  Definition Shifting of large blocks of the Earth's surface Term         Earth's Atmosphere  Definition Primarily Nitrogen(78.08%) and Oxygen (20.95%)   Remaining about 1% Include Carbon dioxide, ozone, water, and argon  First three being important for life     Term         The Greenhouse Effect  Definition Visible light reacts with the Earth's surface and converted to heat Term         Polarity  Definition Direction from the north magnetic pole to the south pole