Transcript Space - Rock Springs Middle School

TCAP Review 6
Components of the Universe - Stars
 Main Sequence Stars: Main sequence stars are usually
medium sized stars. Our sun is a main sequence star.
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.
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.
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.
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.
Our Moon
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.
Comet
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.
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 Earth’s
atmosphere is known as a meteor. If you’ve 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 Earth’s
atmosphere and colliding with the Earth’s surface is known
as a meteorite.
Meteoroid, Meteorite and Meteor
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.
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.
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.
Seasons
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.
Solstice
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.
Equinox
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.
Moon Phases
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
Lunar Eclipse
Solar Eclipse
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.
Tides
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.
Spring and Neap tides