Physics

• Astronomy

  The science of the universe outside of our planet. The branch of physical science dealing with heavenly bodies.
• Astronomy has resulted in many practical inventions and ideas such as calendars, navigational techniques, laws of motion, engineering of products and increased understanding of energy and weather.
• Ancient Greek Philosophers


  • Proposed a spherical Earth
  • Supported the spherical Earth through observations of the moon's shadow during lunar eclipses
  • Listed arguments for a spherical Earth including the position of the North star, the shape of the moon and the sun, and the disappearance of ships over the horizon

  
• Around 240 BC, Eratosthenes attempted to measure the circumference of the Earth and computed it to be approximately 46,250 km.

  
• Astronomical phenomena known to astronomers before the advent of telescopes

  • Daily and annual motion of the stars
  • Rising and setting of the sun
  • Phases of the moon
  • Visibility of planets
  • Eclipses

  
• Diurnal motion


  The apparent daily revolution of the celestial sphere around the celestial poles as a direct effect of the Earth's rotation on its axis
• Annual motion


  The apparent yearly movement of the stars as observed from Earth as a direct effect of the Earth's revolution around the sun
• Precession of the equinoxes


  The cyclic precession or wobbling of the Earth's axis of rotation caused by the gravitational force of the sun and the moon on Earth
• Babylonian and Egyptian civilizations used a primitive version of a sundial called gnomon to systematically observe the motion of the sun.

  
• Phases of the moon


  • New moon
  • Waxing crescent moon
  • First quarter moon/Half moon
  • Waxing gibbous moon
  • Full moon
  • Waning gibbous moon
  • Third/Last quarter moon
  • Waning crescent

  
• Astronomers have discovered that Mercury, Venus, Mars, Jupiter, and Saturn are planets because they have noticed that the stars are in a fixed position with respect to each other, but these "stars" change positions periodically.

  
• Types of eclipses


  • Lunar eclipse (total or partial)
  • Solar eclipse

  
• A lunar eclipse can occur only when the moon is full, and a solar eclipse can occur when the moon moves between the sun and Earth.

  
• Eclipse


  When a heavenly body such as a moon or a planet moves into the shadow of another heavenly body

  
• Types of eclipses on Earth


  • Eclipse of the moon (lunar eclipse)
  • Eclipse of the sun (solar eclipse)

  
• Lunar eclipse


  1. The moon moves in an orbit around Earth

  2. Earth moves between the sun and the moon

  3. Earth blocks the sunlight that normally is reflected by the moon

  4. Earth's shadow falls on the moon

  
• Solar eclipse


  1. The moon orbits Earth

  2. The moon moves between the sun and Earth

  3. The moon blocks the light of the sun from reaching Earth

  4. The moon casts a shadow onto Earth

  
• Tycho Brahe


  Danish astronomer and nobleman who made accurate observations of the movement of celestial bodies in an observatory built for him by King Frederick II of Denmark in 1576
• Johannes Kepler


  German mathematician and astronomer who discovered the basic laws that describe planetary motion
• Tycho Brahe and Johannes Kepler


  Brahe mistrusted Kepler with his astronomical data in fear of being shadowed by his assistant
• Brahe assigned to Kepler the interpretation of his observations of Mars, whose movement did not match Brahe's calculations</b>
• Kepler's first law (law of ellipses)


  Planets follow an oval or an ellipse orbit, with the Sun at one focus of the ellipse

  
• Kepler's second law (law of equal areas)


  An imaginary line drawn from the center of the Sun to the center of a planet sweeps out an equal area of space in equal time intervals
• Kepler's third law (law of harmonies)


  The square of a planet's orbital period is proportional to the cube of a planet's average distance from the Sun
• Kepler was able to formulate his laws of planetary motion from Brahe's data
• Tycho Brahe determined the position of 777 fixed stars accurately

  
• After Brahe died, Emperor Rudolf II assigned Kepler as the new imperial mathematician and passed on Brahe's writings, instruments, and the Rudolphine tables to him
• The Rudolphine tables were the most accurate tables known to the astronomical world
• Cubes of the planet's average distance from the sun


  This occurs when a planet is nearest the sun
• Planetary law that describes how fast a planet moves in its orbit


  It states that there is an imaginary line from the center of the sun to the planet and this sweep out equal areas within equal time intervals
• Danish astronomer who determined the position of 777 fixed stars accurately

  Tycho Brahe

  
• Planets in order of longest time to make one complete revolution around the sun

  • Pluto
  • Neptune
• cubes of the planet's average distance from the sun


  cubos de la distancia media del planeta al sol
• This occurs when a planet is nearest the sun


  Esto ocurre cuando un planeta está más cerca del sol
• Planetary law that describes how fast a planet moves in its orbit


  Ley planetaria que describe qué tan rápido se mueve un planeta en su órbita
• It states that there is an imaginary line from the center of the sun to the planet and this sweep out equal areas within equal time intervals


  Establece que hay una línea imaginaria desde el centro del sol hasta el planeta y que barre áreas iguales en intervalos de tiempo iguales

  
• Danish astronomer who determined the position of 777 fixed stars accurately

  Astrónomo danés que determinó con precisión la posición de 777 estrellas fijas

  
• Pluto


  Plutón
• Neptune


  Neptuno
• The Greeks observed that when the ship sailed, the hull disappeared first, which implied that the surface of Earth was flat