astronomy final 1

early people who thought everything revolved around the earth believed in a

geocentric cosmology

a theory in which everything orbits the earth in uniform circles can not explain

the motion of the planets

Tycho Brahe was able to deduce that a super nova was far away using

a parallax

Copernicus revives the idea of a

heliocentric cosmology

Copernicus calculates the sidereal period of the planets using

their synodic periods

the maximum elongation of a planet is

the largest angle between the planet and the sun

Copernicus's theory did nit make better predictions because he had incorrectly assumed

the planets orbits are circular

ptolemy was able to explain the retrograde motion of the planets using

epicycles

what first made ptolemy's theory appear less attractive was

technological advances leading to better observations

Galileo supported a heliocentric cosmology with his observation of

the phases of Venus

the first reflecting telescope was built by

Issac newton

the total length of a refracting telescope is

the sum of the focal lengths of the eye piece and objective lens

newton used prisms to

show that white light is composed of a spectrum of colors

Newton figured out that the magnitude of the force of gravity has the form

F= G M1 M2/ R^2

when using the scientific method one forms an initial hypothesis by

induction from observations of the world

after forming a hypothesis the next step is to

make a prediction and test it

using the scientific method you may prove

that you are wrong

if two theories explain observations equally well, the simpler theory is better. this is knows as

occams razor

during the course of a night, stars appear to

move in circular arcs around the North Star.

the sun makes a complete loop around the elliptic once every

year

Julius caesar and pope Gregory XIII changed the calendar because

a year is not a whole number of days

a group of stars forming a pattern and the patch of sky surrounding it is

a constellation

a group of stars forming a pattern is

an asterism

the moon rises at midnight the phases of the moon is

third quarter

because the moon is tidally locked to the earth

its rotation period is the same as its orbital period

sidereal means

relative to the distant fixed stars

synodic means

between alignments of three bodies, such as the sun , earth and a third object

the plane of the earths orbit around the sun is

the ecliptic

if the rotation axis of the earth were perpendicular to the plane of the earths orbit around the sun we would

not have seasons

the altitude-azimuth coordinate system is useful because

it will tell you which way to point your telescope

in the alt-az coordinate system the azimuth angle tells you

how far to rotate to the right of north

the right ascension and declination coordinate system is useful because

the coordinates of stars are always the same

in the RA and Dec coordinate system the declination angle tells you

how far to rotate up from the equatorial plane

it is cold in the winter because

our hemisphere is tilted away from the sun

compared to a solar day a sidereal day is

four times shorter

the blackbody spectrum us the spectrum of light

radiated by objects based on temperature

today a telescope generally captures images on a

CCD

Kirchhoff found that each elements has a unique

set of spectral lines

ole romer timed the eclipses of Jupiters moons and determined

the speed of light

using his double slit experiment Thomas young was able to show that light

is a wave

using math James clerk Maxwell was able to show that light

is composed of electric and magnetic fields.

thinking about the blackbody spectrum led max Planck to infer that energy

is quantized

using planks insight and his knowledge of the photoelectric effect Albert Einstein hypothesized that light

is made of photons

as an electron falls from an orbital with an energy of 12.8 eV to an orbital of energy to 10.2 eV

a photon is emitted with an energy of 2.6 eV

Keplers third law relates the size of a planets orbit to its period it states that

period^2 semiaxis major^3