The Universe

1
The Universe

• TCAP Review 6

2
Components of the Universe - Stars

• Main Sequence Stars Main sequence stars are
  usually medium sized stars. Our sun is a main
  sequence star.

3
Components of our solar system

• The Sun is by far the largest object in the solar
  system. It contains more than 99.8 of the total
  mass of the Solar System (Jupiter contains most
  of the rest). Everything found in our solar
  system revolves around the sun.

4
Planets

• There are eight major planets in our solar
  system. A planet is a celestial body moving in
  an elliptical orbit around a star.
• We have two systems of planets in our solar
  system
• The inner planets which are small dense and
  rocky.
• The outer planets which are large and made of
  gases.

5
Dwarf Planets

• A dwarf planet is a celestial body massive enough
  to be spherical, in orbit around the Sun, which
  are not satellites. The crucial factor dividing a
  planet from a dwarf planet is that a planet must
  have succeeded in clearing the area of its orbit
  from debris and other objects, whereas a dwarf
  planet has not.

6
Moons

• Many people think that moons are smaller than
  planets. This, however, is not true. There are
  several moons in the Solar System which are
  larger than both the planets Mercury and Pluto.
  Neither are the moons less exciting than the
  planets. There are moons with volcanos,
  atmospheres, and even quite possibly liquid water
  oceans. The difference between what we call a
  moon and what we call a planet has to do only
  with around what the world revolves, or circles.
  If the object circles the Sun it is called a
  Planet, however, if it circles another world
  instead of the Sun then it is called a moon.

7
Our Moon
8
Comets

• A comet is an icy small Solar System body that,
  when close enough to the Sun, displays a visible
  coma (a thin, fuzzy, temporary atmosphere) and
  sometimes also a tail. Comets are often referred
  to as "dirty snowballs." They are left over from
  the formation of stars and planets billions of
  years ago. Before zipping around the Sun with
  their characteristic big tails, comets that we
  see in our solar system start out as big chunks
  of rock and ice just floating around in something
  called the Oort Cloud. When the gravity from a
  large passing body, like a star, becomes strong
  enough, some large chunks of ice get pulled away
  from the cloud and head toward the Sun. As that
  ball of ice gets close enough to the Sun, its
  heat begins to melt some of the ice that makes up
  the comet. The melted ice becomes a gaseous tail
  that extends away from the source of the heat (in
  this case, the Sun). The tail is pushed out by
  the Sun's solar wind.

9
Comet
10
Asteriods

• Asteroids are metallic, rocky bodies without
  atmospheres that orbit the Sun but are too small
  to be classified as planets. Known asteroids
  range in size from the largest -- Ceres, the
  first discovered asteroid in 1801 -- at about 600
  miles (1,000 kilometers) in diameter down to the
  size of pebbles. Most asteroids are found in a
  belt between the orbits of Mars and Jupiter.

11
Meteoroid, Meteorite and Meteor

• A meteoroid is a small rock or particle of debris
  in our solar system. They range in size from dust
  to around 10 metres in diameter (larger objects
  are usually referred to as asteroids).
• A meteoroid that burns up as it passes through
  the Earths atmosphere is known as a meteor. If
  youve ever looked up at the sky at night and
  seen a streak of light or shooting star what
  you are actually seeing is a meteor.
• A meteoroid that survives falling through the
  Earths atmosphere and colliding with the Earths
  surface is known as a meteorite.

12
Meteoroid, Meteorite and Meteor
13
Rotation and Revolution

• Rotation means to turn on its axis. The Earth
  and moon rotate on their axis. Prograde rotation
  is a planet spinning counterclockwise and retro
  grade is a planet spinning clockwise. Venus and
  Uranus are the only planets with retrograde
  rotation.
• Revolution means to revolve around another body.
  The Earth revolves around the sun in an orbital
  path. The moon revolves around the Earth in an
  orbital path.

14
(No Transcript)
15
What makes a day

• The time it takes Earth to complete one rotation
  is considered a day. It takes 24 hours to
  complete is responsible for day and night.

16
Why do we have seasons on Earth?

• The Earth's seasons are not caused by the
  differences in the distance from the Sun
  throughout the year (these differences are
  extremely small). The seasons are the result of
  the tilt of the Earth's axis.
• The Earth's axis is tilted from perpendicular to
  the plane of the ecliptic by 23.45. This tilting
  is what gives us the four seasons of the year -
  spring, summer, autumn (fall) and winter. Since
  the axis is tilted, different parts of the globe
  are oriented towards the Sun at different times
  of the year.
• Summer is warmer than winter (in each hemisphere)
  because the Sun's rays hit the Earth at a more
  direct angle during summer than during winter and
  also because the days are much longer than the
  nights during the summer. During the winter, the
  Sun's rays hit the Earth at an extreme angle, and
  the days are very short. These effects are due to
  the tilt of the Earth's axis.

17
Seasons
18
Solstice

• A solstice is an astronomical event that occurs
  twice each year as the Sun reaches its highest or
  lowest excursion relative to the celestial
  equator on the celestial sphere. As a result, on
  the day of the solstice, the Sun appears to have
  reached its highest or lowest annual altitude in
  the sky above the horizon at local solar noon.
• The summer solstice is June 21. We have more
  daylight hours on this day than any other day of
  the year in the Northern Hemisphere.
• The winter solstice is December 21. We have less
  daylight hours on this day than any other day of
  the year in the Northern Hemisphere.

19
Solstice
20
Equinox

• An equinox occurs twice a year, when the tilt of
  the Earth's axis is inclined neither away from
  nor towards the Sun.
• The fall equinox is September 21.
• The spring equinox is March 21.
• On these two dates we have equal amounts of
  daylight and darkness all over the Earth.

21
Equinox
22
Moon Phases

• The moon goes through phases as it revolves
  around the Earth because it reflects sunlight.
  It takes about one month for the moon to complete
  one lunar cycle, which is one revolution. It
  also takes the moon about one month to rotate on
  its axis. It revolves and rotates at the same
  speed.

23
Moon Phases
24
Eclipse

• A lunar eclipse occurs when the moon passes
  through the shadow of the earth ( During a Full
  moon). A lunar eclipse can last up to an hour and
  a half. During a lunar eclipse the moon may turn
  a reddish color. It is not dangerous at all to
  look at a lunar eclipse because the moon does not
  make its own light.
• A Solar Eclipse occurs when the moon goes in
  front of the sun and blocks most of the sun's
  light from the earth (During a New Moon). During
  a total eclipse all you can see from earth is a
  ring of light around the moon which is part of
  the sun the moon did not cover. It is dangerous
  to look at a solar eclipse directly, even if you
  have sun glasses or smoked glass

25
Lunar Eclipse
26
Solar Eclipse
27
Tides

• The moon's gravity pulls the oceans nearest it
  towards it hence the high tide on the lunar side
  of the earth. The Moon's influence gets weaker
  with distance so the ocean on the far side of the
  Earth form the moon gets 'left behind'. In effect
  the Earth is pulled slightly more towards the
  moon than the oceans on the opposite side of the
  Earth. So there is a bulge or high tide at the
  same time on both sides of the Earth. Because of
  this there are two high tides and two low tides
  at each location on the earth every day.

28
Tides
29
Spring and neap tides

• When the Sun, Earth Moon are in alignment with
  one another ( during new or full moons) spring
  tides occur. Spring tides happen twice a month
  Spring tides are higher than average. When the
  Sun - Earth line is at right angles to the Earth
  (During 1st and last quarter) we see "neap"
  tides, which are lower than average. A tide in
  which the difference between high and low tide is
  the least. Neap tides occur twice a month when
  the Sun and Moon are at right angles to the
  Earth. When this is the case, their total
  gravitational pull on the Earth's water is
  weakened because it comes from two different
  directions.

30
Spring and Neap tides