MOD2: Astronomical Phenomena Before the Advent of Telescopes

• MOON - also known as a satellite, is a natural object that orbits a larger object.
• SOLAR ECLIPSE - a type of eclipse that occurs when the Moon passes between the Sun and Earth, and the Moon fully or partially blocks the light from the Sun.
• LUNAR ECLIPSE - one of the cyclically recurring apparent forms of the moon
• GIBBOUS - the figure of the moon that is more than half full, looking swollen on one side
• CRESCENT - the figure of the moon that appears as a curve with pointy ends
• WAXING - growing; describes the moon when the illuminated portion is increasing
• WANING - shrinking; describes the moon when the illuminated portion is decreasing
• PLANET - a planet is a large round object that orbits the Sun and has cleared out most of the other objects in its orbit.
• SOLAR SYSTEM - The Sun and all of the planets, comets, etc. that revolve around it.
• RISING & SETTING OF THE SUN

  • Babylonian and Egyptian civilizations used a primitive version of a sundial, called gnomon, in systematically observing the motion of the sun
  • By looking at the shadows that the gnomon casts, they were able to observe that the sun rises in the eastern part of the sky, reaches its highest point in midday, and sets in the western part of the sky
• POINT WHERE THE SUN RISES AND SETS ON THE HORIZON

  • The points where the sun rises and sets on the horizon vary over a year and these variations happen periodically - they observed that these variations are related t the weather
• POINT WHERE THE SUN RISES AND SETS ON THE HORIZON

  • Sun would rise and set at slightly different times every day. It would also take a slightly varied path across the sky every day of the year - The combination of Earth's elliptical orbit and the tilt of it's axis results in the Sun taking different paths across the sky at slightly different speeds each day. This gives us different sunrise and sunset times each day.
• POINT WHERE THE SUN RISES AND SETS ON THE HORIZON

  • The path the sun appears to take around the celestial sphere each year is called the ecliptic
• Earth’s moon is the fifth biggest moon in the solar system.
• On average, the distance between the Earth and the moon is 384,000 kilometres.
• It takes 27 days, 7 hours, and 43 minutes for our Moon to complete one full orbit around Earth. This is called the sidereal month, and is measured by our Moon's position relative to distant “fixed” stars.
• It takes our Moon about 29.5 days to complete one cycle of phases (from full Moon to full Moon). This is called the synodic month.
• There are eight phases within about a month.
• A new moon appears only when the moon is on the side of the earth most directly in line with the sun.
• Within a few days after the dark moon, a thin waxing crescent moon may be seen low in the western sky shortly after sunset.
• First quarter - Half the side of the moon facing the earth appears illuminated.
• During the next week, more and more of the sunlit part is exposed to us as the moon goes through its waxing gibbous phase.
• Full Moon- the whole side of the moon is now illuminated to viewers from the Earth. The full moon  rises in the east as the sun sets in the west. 
• The cycle reverses during the following two weeks as  we see less of the sunlit side while the moon  continuously moves in its orbit. This movement produces the waning gibbous
• Last quarter - like the first quarter, it is seen illuminated on half the side facing the Earth
• The following crescent gets thinner and thinner, it is known as the waning crescent moon or the old moon as it approaches the phase of the new moon to complete the cycle
• LUNAR ECLIPSE - SEM
• SOLAR ECLIPSE - SME
• LUNAR ECLIPSE

  • When the moon passes into the shadow of the Earth.
  • Full Moon
  • Twice every year
  • 1 hour
• SOLAR ECLIPSE

  • Occurs when the Moon's shadow fall of the Earth.
  • Because of the large size of the sun, rays of sunlight taper to provide an umbra and a surrounding penumbra.
  • New moon
  • Twice every three years
  • Few minutes
• Diurnal motion is the apparent daily revolution of the celestial sphere around the celestial poles as a direct effect of the Earth’s rotation on its axis. In other words, it refers to the apparent movement of stars and other celestial bodies around Earth. The circular path that the celestial bodies take to complete the diurnal motion is called diurnal circle. The apparent motion of celestial bodies viewed from Earth is east to west. If you observe the night sky, the stars seem to move in a counter clockwise direction (from east to west)
• Annual motion is the apparent yearly movement of the stars as observed from Earth as a direct effect of the Earth’s revolution around the sun.
• As the sun revolves around the ecliptic, it intersects the celestial equator twice during a year at two points. These points are called the equinoxes: vernal and autumnal. During an equinox, the length of daytime is almost equal to the length of nighttime. Vernal or spring equinox happens every March 20 while autumnal equinox occurs every September 22.
• PLANETS DISCOVERED BEFORE THE INVENTION OF TELESCOPE

  1. Mercury
  2. Venus
  3. Mars
  4. Jupiter
  5. Saturn
• The sun revolves 360 degrees a year around a path on the celestial sphere called the ecliptic.