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Modern Astronomy and Cosmology |
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| Study of the entire universe using scientific instruments, methods and simulations |
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Distance from the sun to the earth |
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150 million km 1.5 x 10^11 = 93 million miles |
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| A group of superclusters in which our cluster is a part of |
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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 |
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| Rate of expansion of the universe that seems to be increasing as if it were pushed outward by some unknown sources of energy |
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1)Prehistoric (<500 B.C.) 2)Classical (500 B.C. - 1400 A.D.) 3)Renaissance (400-1650) 4)Modern (After 1650 |
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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" |
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All celestial objects (stars, planets, sun, moo) moved as if attached to the celestial sphere |
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Motion around the Celestial Sphere |
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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 |
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| Determined by the time spent in front of a particular constellation |
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Who invented the telescope? |
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Johannes Lippershey, dutch spectacle maker Galileo took idea from Lippershey |
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1) Magnify Images 2) Gather lots of light and see faint objects |
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Sir Isaac Newton 1643-1727 Cambridge University |
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Considered most influential person in the history of physics Founding father of planetary motion |
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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 |
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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 |
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Newtons 2nd Law Acceleration |
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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) |
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Amount of matter an object contains Measure of an objects inertia Never changes |
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Newtons Second Law of Motion |
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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) |
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Newtons Third Law of Motion |
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When two objects interact, they create equal and opposite forces on each other |
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Newtons Law of Universal Gravity |
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Everything attracts everything else G (gravitational constant) = 6.67 x 10^-11 Nm^2/kg^2 |
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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 |
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Photoelectric Effect (Einstein) |
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| Light of a specific energy strikes solid surfaces, only electrons of a specific energy is ejected. |
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| h = 6.63 x 10^-34 Nms(Newton meter seconds) |
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Refractor - light bent by lenses Reflector - light bent using mirrors |
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Changing of the direction of a beam of light as it enters a new medium For example - entering water, lenses, atmosphere |
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Largest visible telescopes Keck twin- 10 meter, multi-mirror telescopes in Hawaii |
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| How big must a telescope be to see two objects individually |
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| One of the first recorded astronomical objects |
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Advantages of space based/ground based telescopes |
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Ground - Increased collecting power, equipment easily fixed Space - freddom from atmospheric blurring/absorption |
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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 |
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| Shifting of large blocks of the Earth's surface |
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Primarily Nitrogen(78.08%) and Oxygen (20.95%) Remaining about 1% Include Carbon dioxide, ozone, water, and argon First three being important for life |
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| Visible light reacts with the Earth's surface and converted to heat |
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| Direction from the north magnetic pole to the south pole |
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