Pt 1 Into Astronomy

Heliocentrism

Belief in which the Earth and planets revolve around the Sun at the center

geocentrism

Belief in which the earth is at the center of the universe

Stellar parallax

the apparent movement against the background of more distant stars as the Earth revolves around the Sun.

Eccentricity

measure of how far an orbit deviates from circular

Perfectly circular orbit has what eccentricity?

0

Very eliptical orbit would have what eccentricity?

1

perihelion

point in the orbit of a planet, asteriod, or comet at which it is closest to the sun

Aphelion

the point in the orbit of a planet, asteroid, or comet at which it is furthest from the sun

Galileo Galilei

Played major role in Scientific Revolution, improved the telescope, supports Copernicanism (heliocentrism rather than geocentrism)

Nicolaus Copernicus

Correctly placed the sun at the center of the solar system but thought planets orbited around in perfect circles

Johannes Kepler

Took Copernicus’ model and improved on it, saying that planets did not orbit in perfect circles but were more eliptical. Also developed his 3 laws of planetary motion.

Kepler’s 1st Law

Law of Ellipses: planets move in elliptical orbits around the Sun

Kepler’s 2nd Law

Law of Equal Areas: planets move faster when closer to a focus and slower when farther away.

Kepler’s 3rd Law

Law of Harmonies: the time a planet takes to orbit the sun increases with the radius of its orbit (the period is proportional to half the long axis of the ellipse raised to the 3/2 power

Most eccentric planet

Mercury

Least eccentric planet

Mars

Eccentricity

the distance between the two focus points/length of the major axis (or e= (a-p)/(a+p)

AU

Astronomical Unit, or the distance from Earth to the Sun

Order of planets

Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune

slowest orbiting planet

Neptune