Astronomy Exam 1

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Galileo

Back 1

Observation w/ first telescopes that supported heliocentric view.

1st to use telescope for astronomy.

More stars, nebulous blurs(Milky Way) made of many stars.

Jupiter satellites orbit. Phases of Venus support heliocentric. Moon rough & irregular. Sunspots = imperfect.

Persecuted by Roman Inquisition.

Front 2

Isaac Newton

Back 2

"Marvelous Year"

Calculus, theory of gravity (Principia), explanation for nature of light, invented reflecting telescope.

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Newton's Laws

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1. Inertia - a body continues in a stte of motion or rest unless made to change by an outside force.

2. F=ma - the amount of acceleration that a force produces depends on the mass being accelerated.

3.Action-Reaction: when two bodies interact, they create equal and opposite forces on each other.

Universal Law of Gravity: F=GMm/r^2

Front 4

What causes tidal bulge?

Back 4

Differential gravitational force the Moon exerts on Earth's waters.A portion of the Earth's surface is always 8,000 mi closer to the Moon than the opposite surface.

Front 5

Spring vs neap tides?

Back 5

Spring tides: new and full moon phases. (Max tides)

Neap tides: near quarter moon phases.(Min. tides)

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High & low tides?

Back 6

High tide on side of Earth near Moon results from water being pulled away from the Earth & toward Moon, the high tide of the opposite side of the Moon results from Earth being pulled away from the water & toward Moon.

Low tide occurs between high tides.

Cycles high to low every 6 hrs 12 mins

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Wax vs Wane

Back 7

Wax - increasing illumination w/ time

Wane - decreasing illumination w/ time

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New Moon

Back 8

unilluminated, rises at sunrise

between new and 1st quarter is waxing crescent

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First Quarter

Back 9

half illuminated

bet. 1st Q & Full is waxing gibbous

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Full Moon

Back 10

fully illuminated, rises at sunset

between full & 3rd Q is waning gibbous

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Solar eclipse

Back 11

occur at time of New Moon if Moon lies directly between Earth and Sun

Partial - moon doesn't completely cover sun

Total - moon completely covers Sun. Lasts less than 3-7 mins at any one place.

Annular - moon nearly perfectly eclipses sun but is at a larger than normal distance from earth. Ring of sunlight around dark Moon.

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Lunar eclipse

Back 12

occur at full moon when earth lies between moon & sun.

Front 13

What are seasons caused by?

Back 13

the plane of the Earth's rotation is not aligned w/ the plane of Earth's revolution about the Sun. This is called obliquity of the ecliptic.Opposite seasons in northern & southern hemispheres.

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Examples of gravity(dominant force in solar system)

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1.Holds sun together, pressure from high temperatures tries to push sun apart.

2. causes planets,asteroids,and comets to orbit Sun.

3. Earth-Moon system causes tides.

Front 15

celestial coordinates

Back 15

locations of stars in sky.

longitude = right ascension
latitude=declination

local sidereal time = tells when a star of a particular right ascension will be at its highest point

zenith = point in sky directly overhead

ecliptic = apparent path of the sun through the sky. all planets & moon found here. constellations along this are "constellations of the zodiac."

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Aurora

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arise when charged particles are produced by a solar storm. Charged particles become part of the solar wind, when particles encounter Earth's magnetic field, they are guided to the poles. Once it hits the molecules in the atmosphere a glow is produced.

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time zones

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24, each 15 degrees wide in longitude. Time is adjusted in each so the sun will be highest pt in sky within ~ 1/2 hr of noon each day.

Front 18

precession of the equinox

Back 18

earth's axis of rotation changes the direction it's pointed w/ a cyclic period of 26,000 yrs.

Front 19

electromagnetic radiation

Back 19

astronomers observe astronomical objects by observing how they emit & absorb EM radiation.

photons

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photons (EM radiation)

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wave-like & carry energy.

diffract (spread out) when they pass by the edge of an opaque body.

wavelength of photon inversely proportional to its energy(shorter wavelength, greater energy).

When separated into their component wavelengths/energies, EM spectrum formed.

Front 21

Types of EM radiation. Dec. order of energy (short to long wavelength)

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Gamma Rays - energetic processes. observed w/ space telescopes cuz ozone absorbs most.

X-rays - energetic processes & absorbed by ozone.

UV radiation - most emitted by energetic processes & hot stars. mostly absorbed by ozone.

Visible rad. - moderate temp stars like sun emit large fraction of their energy @ visible wavelengths. Passes through atmosphere.

IR rad - most emitted by cool stars, most wavelengths absorbed by water vapor in atmosphere.

Radio Waves - smallest eng & longest wavelengths. Most emitted by plasmas associated w/ magnetic fields. Generally pass thru but shorter length radio waves bounce off ionosphere

Front 22

Visible light

Back 22

ROY G BIV

Red = longest wavelength
Violet = shortest wavelength

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Telescope collecting area

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determines how much em rad. from an object can be collected & focused in a given interval of time. Larger area = further objects.

Front 24

focal length

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determine scale of image formed. magnification depends on scope focal length & eyepiece focal length. f-value (length/diameter) = image brightness.

Front 25

Optical telescope types

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Refracting: focuses light w/ lenses. Expensive & suffer from chromatic aberration.

Reflecting: focus light w/ mirrors. vary in cost aberrations determined by the design.

Some use both, usually expensive.

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Photometry

Back 26

measuring of the strength(magnitude) of light. Done w/ photographic plates as detectors or CCDs (charged couple deviced)

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Magnitude scale

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invented by Hipparchus.

magnitude of a star decreases by 1 unit, star is 2.5x brighter. If dec. by 5 units, star is 100x brighter.

Front 28

Keck 10-m telescopes

Back 28

largest ground-based telescopes. Low cost design to achieve large collecting areas.

Front 29

Spectroscopy

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break up UV, optical, & IR light into its component wavelengths or energies using prisms or diffraction gratings. Used to study details of the spectrum of an object.

Front 30

Solar nebula hypothesis

Back 30

planets formed out of a rotating disk of gas & dust around the protostar that formed the Sun.

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Planet Order

Back 31

mercury, venus, earth,mars,jupiter,saturn,uranus,neptune

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Terrestrial planets

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dense rocky bodies ~ diameter of Earth or smaller which may have a gaseous atmosphere

Mercury,venus,earth,mars

Front 33

Jovian Planets

Back 33

giant gaseous many times the diameter of Earth. large & low density. All have ring systems & moons.

jupiter,saturn,uranus,neptune

Front 34

Asteroids

Back 34

orbit around sun.

most confined to an orbit between mars & jupiter. non-luminous chunks of rock smaller than a planet. most small enough that gravity doesn't force them into spheres.

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Comets

Back 35

asteroid-sized bodies that contain ice & travel in elongated orbits around Sun. absorbed energy from sun and melt & evaporate the ice and producing a huge cloud and a tail of gas and dust that reflect sunlight while near the Sun.Meteor showers occur when earth passes through the debris trail.

tail points away from sun

Front 36

Meteoroids

Back 36

non-luminous chunks of rock before they enter Earth's atmosphere. Friction from atmosphere causes them to burn and as they streak across sky they are METEORS (luminous object).

When meteor does not burn up completely and impacts earth it is a meteorite

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Yucatan Peninsula meteorite

Back 37

65 million yrs ago, cloud raised by impact covered Earth for many years and a layer of clay containing iridium settled. 75% of species wiped out, like dinosaurs.

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Planetesimal

Back 38

one of the small bodies formed from solar nebula and came together w/ others to form a protoplanet

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Differentiation

Back 39

when planetesimals grew to large enough size, release of energy by radioactivity caused layering of light & heavier materials in protoplanet

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outgassing

Back 40

process by which gasses released from planet's interior during differentiation, creating an atmosphere

Front 41

Oort Cloud

Back 41

spherical shell of comet nuclei whose orbits lie in realm out past the planets in SS.

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Models

Back 42

understand physical processed & make predictions.

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Aristotle

Back 43

developed geocentric model, dominated cosmological thought for ~1800 yrs. Used logic and detailed reasons (i.e. stellar parallax).

Earth's shadow, moon shape, earth-centered cuz everything falls, stellar parallax.

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Quintessence

Back 44

5th element in Greek model.

unchanging transparent element that formed the crystalline spheres that held the stars & planets(wanderers) in place.

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Greeks

Back 45

used invented & developed scientific theory

believed moon revolved around earth and sun more distant than moon.

Earth & moon reflective, sun creates light.

Conceptual understanding of moon phases & eclipses. Could predict accurately.

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Light year

Back 46

speed of light = 186,000mps. time it takes light travel A to B indicates distance.

5.88 x 10^12 miles = 1 light year

Front 47

Copernicus

Back 47

catholic clergy

proposed heliocentric theory in 1512.

delayed publication of Commentariolus until death.

Front 48

Astrology vs Astronomy

Back 48

astrology - believe each part of human anatomy controlled by a specific sign of the Zodiac.

Astronomy - the scientific study of celestial objects and phenomena that originate outside the Earth's atmosphere

Front 49

Johannes Kepler

Back 49

scientist,mathematician,philospher, and mystic.

Difficult life - protect mom from being burned at stake as a witch (aunt was). Had myopia and multiple vision.

Very religious but persecuted by Catholics & Protestants for Copernican views.

Worked w/ Tycho Brahe

3 laws of planetary motion. Paved way for Newtons theory of gravity.

Front 50

Kepler's Laws of Planetary Motion

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1. Planetary orbits are ellipses not circles.

2.Planet in its orbital plane sweeps out equal areas in equal amounts of time. Closer a planet is to the Sun, faster it moves.

3.P^2 = D^3. P is period of a planet's revolution around sun in yrs and D is planet's distance from Sun in AU (astronomical units)

Front 51

AU

Back 51

astronomical units = avg distance from Earth to the Sun. 93,000,000 mi.