Download Space Exam Review

EARTH AND SPACE UNIT
Earth and Space Unit
The Study of the Universe
Lets study the Structure of the Sun
THE SOLAR SYSTEM
Measuring Distances in the Solar System
 1 AU is the average distance between the Sun
and the Earth (150 000 000 km)
 1 AU = 150 000 000 km
o Jupiter is 780 million km from the Sun,
therefore, Jupiter is 5.2 AU from the Sun
Asteroids
 small celestial objects in the Solar System
composed of rocks, minerals and metals
 smaller than planets, range in size, have no
definite shape
 lots located in the asteroid belt between
the orbits of Mars and Jupiter (this asteroid
belt also separates the inner and outer
planets)
Satellites
 small celestial bodies that orbit a larger one
(planet) in a fixed path (example – moons)
Meteoroids
 celestial objects even smaller than asteroids composed of rock
and iron or dust – many are asteroid fragments
 can vary in size, from the size of dust particles to the size of
buildings
 When they are caught in the Earth’s atmosphere, friction causes
them to burn up, creating a streak of light across the sky. They are
then referred to as Meteors or A SHOOTING STAR!!! (Which occur
once every 15 minutes on average).
 If the meteor does not burn up completely, small pieces may land
on the surface of the Earth, which is referred to as a Meteorite
Comets
 large chunks of ice, dust and rock that orbit the Sun (the orbit can take a few
years to a hundred thousand years) (nicknamed “Dirty Snowballs”)
 can be 100m to 40 km in diameter
o Short-period comets: originate from just beyond Neptune and orbit the
Sun in less than 200 years (for example, Halley’s Comet which takes 75-76
years to orbit)
o Long-period comets: originate from a spherical cloud of debris further
than Pluto and orbit the Sun in more than 200 years (for example, HaleBopp Comet which takes 2380 years to orbit)
 When comets come close to the Sun, the surface sublimates (changes from
solid to gas) and the icy nucleus heats up; therefore, gases and dust escape
in cloud called a “coma”. Radiation and solar wind from the Sun exert a force
on the coma causing a gaseous tail.
Planetary Motion
Axial Tilt:
the Earth’s axis is tilted
23.5o from the plane of
the Earth’s orbit.
So the Sun and planets
appear to move along a
tilted line in the sky.
Rotation –
the turning of an object around its own axis
**The Earth’s rotation is 24 hours
 creates day and night
Revolution – the movement of an object around
another object (orbit); this movement is not in a perfect
circle, but in an elliptical shape
Since the Sun in not directly in the centre of the ellipse,
the Earth is actually closer to the Sun in December than
it is in June!!!
The Earth revolves around the sun every 365.24 days
 this is our year
Tides
The water moves
more than the
solid Earth does.
There are two high
tides and two low
tides per day.
Solar vs. Lunar
Tides
The Sun is more massive but
very far away:
Solar tide = ½ Lunar tide
Solar and Lunar tides may
work together or against
each other.
The Earth’s rotation
makes the sky
appear to revolve
around us.
Polaris: does not
appear to move
because it's aligned
with the Earth's axis.
Classifying Stars
• Stars are classified by their size,
temperature and brightness.
• The sun is neither the largest nor
the brightest star but it is the
closest to us.
Apparent Magnitude
• A star’s apparent magnitude is its brightness as
seen from Earth.
• How does it appear.
• The sun appears to be the brightest
Absolute Magnitude
• A star’s absolute magnitude is the brightness the
star would have if it were at a standard distance
from Earth.
•
http://cassfos02.ucsd.edu/public/tutorial/HR.html
Life Cycle of a Star
Small or Medium Star
Black Dwarf
Red Giant
1.Nebula/Protostar
Giant or Supergiant Star
Supernova
Black Hole
Neutron Star
• 1 light year is the distance that light can
travel in 1 year, at its speed of 300 000
km/s
• 1 light year = 9.5x1012 km
STAR CLUSTERS
All galaxies contain star clusters
which are groups of stars that:
• Develop together from
the same NEBULA
• Are gravitationally bound
• Travel together
STAR CLUSTERS
There are two types of star clusters:
• Open star clusters are collections of six to
thousands of usually young stars
• Globular clusters are ball-shaped
collections of thousands to millions of very
old stars
There are approximately 20 000 open star
clusters found within the main disc of the
Milky Way.
TYPES OF GALAXIES
Galaxies are collections of millions
to hundreds of billions of stars,
planets, gas, and dust, measuring
up to 100 000 light years across.
They come in different shapes and
sizes and are spread across
the Universe