The Earth, Moon and Sun

• The Earth is a rocky planet that rotates in a near circular orbit around the Sun
• The Earth rotates on its axis, which is a line through the north and south poles

  • The axis is tilted at an angle of approximately 23.5° from the vertical
• The Earth completes one full rotation (revolution) in approximately 24 hours (1 day)

  • This rotation creates the apparent daily motion of the Sun rising and setting
  • Rotation of the Earth on its axis is responsible for the periodic cycle of day and night
• The Earth's rotation around its axis creates day and night

  • Day is experienced by the half of the Earth's surface that is facing the Sun
  • Night is the other half of the Earth's surface, facing away from the Sun
• • Day and night are caused by the Earth's rotation

  A) earth tilt

  B) day

  C) equator

  D) night

  E) sun rays

  
• The Earth's rotation on its axis makes the Sun looks like it moves from east to west

  • At the equinoxes the Sun rises exactly in the east and sets exactly in the west
  • Equinox (meaning 'equal night') is when day and night are approximately of equal length
• The exact locations of where the Sun rises and sets changes throughout the seasons
• In the northern hemisphere (above the equator):

  • In summer, the sun rises north of east and sets north of west
  • In winter, the sun rises south of east and sets south of west
• The Sun rises in the east and sets in the west. Its approximate area changes throughout the year

  A) summer

  B) equinox

  C) winter

  D) noon

  E) south

  F) east

  G) west

  
• The Sun is highest above the horizon at noon (12 pm)
• In the northern hemisphere, the daylight hours are longest up until roughly the 21st June

  • This day is known as the Summer Solstice and is where the Sun is at its highest point in the sky all year
• The daylight hours then decrease to their lowest around 21st December

  • This is known the Winter Solstice and is where the Sun is at its lowest point in the sky all year
• The Earth orbits the Sun once in approximately 365 days

  • This is 1 year
• The combination of the orbiting of the Earth around the Sun and the Earth's tilt creates the seasons
• Seasons in the Northern hemisphere caused by the tilt of the Earth (1)

  • Over parts B, C and D of the orbit, the northern hemisphere is tilted towards the Sun
  • This means daylight hours are more than hours of darkness
  • This is spring and summer
  • Over parts F, G and H of the orbit, the northern hemisphere is tilted away from the Sun
  • The situations in both the northern and southern hemisphere are reversed
  • It is autumn and winter in the northern hemisphere, but at the same time it is spring and summer in the southern hemisphere

  
• Seasons in the Northern hemisphere caused by the tilt of the Earth (2)

  • At A and D:
  • Night and day are equal in both hemispheres
  • These are the equinoxes
  • At C:
  • This is the summer solstice
  • The northern hemisphere has the longest day, whilst the southern hemisphere has its shortest day
  • At G:
  • This is the winter solstice
  • The northern hemisphere has its shortest day, whilst the southern hemisphere has its longest day

  
• Earth Orbit

  A) spring

  B) earth titled on axis

  C) summer

  D) autumn

  E) winter

  
• The southern hemisphere is tilted away from the Sun

  • This means there are shorter days than night
  • This is autumn and winter
• The Moon is a satellite around the Earth

  • It travels around the Earth in roughly a circular orbit once a month
  • This takes 27-28 days
• The Moon revolves around its own axis in a month so always has the same side facing the Earth

  • We never see the hemisphere that is always facing away from Earth, although astronauts have orbited the Moon and satellite have photographed it
• The Moon shines with reflected light from the Sun, it does not produce its own light
• The way the Moon's appearance changes across a month, as seen from Earth, is called its periodic cycle of phases
• Phases of the Moon as it orbits around Earth

  • In the image, the inner circle shows that exactly half of the Moon is illuminated by the Sun at all times
  • The outer circle shows how the Moon looks like from the Earth at its various positions
• Phases of the Moon

  A) first quarter

  B) earth

  C) waxing crescent

  D) moon

  E) new

  F) waning crescent

  G) last quarter

  H) waning gibbous

  I) full

  J) waxing gibbous

  
• In the New Moon phase:

  • The Moon is between the Earth and the Sun
  • Therefore, the sunlight is only on the opposite face of the Moon to the Earth
  • This means the Moon is unlit as seen from Earth, so it is not visible
• At the Full Moon phase:

  • The Earth is between the Moon and the Sun
  • The side of the Moon that is facing the Earth is completely lit by the sunlight
  • This means the Moon is fully lit as seen from Earth
• In between, a crescent can be seen where the Moon is partially illuminated from sunlight
• It takes one month for the moon to orbit the Earth which creates the moon cycle
• What does the moon look like in its 1st quarter?

  Half lit.
• What happens to the moon 7 days after the 1st quarter?

  it will be fully lit
• Why does the moon rise and set?

  Earth rotates on an axis
• What is the time for a complete lunar cycle?

  28 days
• Why does the moon have phases?

  we see the moon because of the reflected light from the sun and this light only illuminates the side facing the sun so during each phase we see part of the dark side and part of the light side
• Why do we never see the other side of the moon?

  the moon rotates on an axis and our speed of rotation matches the moon