the earth in space - cambridgecsd.org
TRANSCRIPT
The Earth in Space
I. The Solar System - the solar system is described as the Sun, the
eight planets (3 dwarfs) that orbit the Sun, and the small
interplanetary bodies such as asteroids and comets.
A. The Sun - is a medium age star (between 5 and 6 billion years
old), and is composed of mainly helium and hydrogen. The sun emits
radiation in many wavelengths with temperatures ranging from 7,000
to 90,000 degrees F. The Sun has a period of high activity of solar
storms, also called sunspots, every eleven years.
B. Terrestrial Planets - these are the four closest planets to the
sun that include Mercury, Venus, Earth and Mars. They are mainly
composed of rock surrounded by a thin envelope of gas.
C. Gas Giants - these are the five outer planets that are mainly
composed of water vapor, methane, ammonia gases. They include
Jupiter, Saturn, Uranus, Neptune and the 3 dwarfs.
D. Asteroids - Located in a belt between Mars and Jupiter,
asteroids are rocky objects that range in size from 600 miles across to
mere pebbles. There are thousands of asteroids in the solar system.
E. Comets - are icy objects that originate from far out of the solar
system. Because they are composed of ice, the energy from the Sun
vaporizes the ice and forms a comet’s tail.
F. Meteorites – smaller chunks of rocks traveling within the solar
system. Classified as stony or iron.
II. Models of Celestial Motion -
A. Geocentric Model of the Universe - this proposed that the earth
was the center of the universe, around which all of the stars and
planets rotated. This was first proposed by Aristotle, a Greek
philosopher (384-322 BC). This did not fully explain the motions of
the planets.
B. Heliocentric Model of the Universe - this proposed that the
earth, along with the other planets orbited around the Sun. This was
developed by Nicholas Copernicus , a Polish Astronomer, in 1514.
II. Apparent Motion of the Celestial Objects
A. Apparent Motion of Celestial Objects - All celestial objects
appear to move across the sky in an arc from east to west. The
speed of movement of celestial objects is approximately 15
degrees per hour, which is also known as the daily motion.
1. Evidence of the Earth’s Rotation - two pieces of
evidence can be used to suggest that the
earth is rotating.
a. Foucault’s Pendulum - when a pendulum is
allowed to swing freely, over time it will change the
path of its swing as the earth rotates under it.
b. The Coriolis Effect - the tendency of particles
on earth to be directed to the right of travel in the
Northern Hemisphere.
V. The Earth’s Revolution - the earth is also revolving around the Sun.
Revolution is the movement of one body around another. The period
of the earth’s revolution is 365.25 days.
A. --Time and Earth Motions - time is greatly influenced by the
motions of the earth, and other celestial bodies.
1. Year - is the time it takes for the earth to make one complete
orbit around the Sun.
2. Month - is the time it takes for the Moon to go through one
full period of phases.
3. Solar Noon - Time of day when the sun is at its highest
altitude above the horizon.
The Pale Blue Dot
B. Orbital Motion - In our solar system, the earth, moon, and
other planet’s orbits are elliptical. An ellipse is a curved path of
a moving object. The eccentricity of an ellipse can be
determined by the following formula (see reference tables):
Eccentricity = distance between foci/length of major axis
1. Earth’s Orbit –
2. Motions of the Moon - The moon revolves around the earth
once every 27 1/3 days.
Theory of the Moon's Formation - The moon is
believed to have been formed when a massive
object collided with the Earth early in its
formation.
a. Phases of the Moon - because the Moon is revolving
around the earth, one side is always bathed in shadow
from the Sun. When this shadow is observed from earth,
it appears to change the visible portion of the Moon.
i. The phases of the Moon include: New Moon,
New Crescent, First Quarter, New Gibbous,
Full, Old Gibbous, Third Quarter, Old
Crescent, and New Moon again.
iii. The Moon and the Tides - Tides are the
result of the gravitational attraction between the
Sun, Moon, and Earth. The tidal bulge is the
high water mark that is raised by the Moon and
Sun's Gravity.
Neap Tide - Lowest tidal range of the month
Spring Tide - Highest Tidal Range of the month
- The Moon's tidal force may also flex the earth's
outer crust, which may trigger earthquakes and
volcanoes.
iv. Eclipses
- Solar Eclipse - when the moon passes in front
of the Sun.
-
- Lunar Eclipse - when the Earth casts its
shadow on the Moon.
III. Beyond the Solar System - the solar system is one of 100 billion other
stars that together make up the Milky Way galaxy. A galaxy is a huge
cluster of stars that spirals around a central point. The solar system is
about half way out in the center of one of the arms of the Milky Way.
The Milky Way Galaxy is approximately 100,000 light years across.
A light year is the distance that light travels in one year (6.25 trillion
miles). Light travels at 186, 000 miles per second. The Milky Way is
part of a cluster of 30 galaxies in our local area.
A. Types of Galaxies - There are three main types of galaxies,
spiral, elliptical, and irregular.
B. Stars - A star is defined as a large, hot, glowing ball of gas that is
powered by nuclear fusion. Stars are classified by their size,
temperature, color, and brightness. This classification is usually
based on a stars age or stage of life. The various stages and types of
stars include: nebula, proto-stars, main sequence, dwarfs, giants,
super giants, neutron stars, pulsars, super nova, and black holes.
Interstellar medium
Nebula
Protostar
Main Sequence
Red Giant
Planetary Nebula
White Dwarf
Red Supergiant
Super Nova
Black Hole
Neutron Star – Pulsar
Star System Formation
1. Star Classification - The Hertzsprung- Russell or HR
diagram is used to classify stars by their color, temperature,
and luminosity.
2. Spectral Analysis and Doppler Shift
- Spectrum - (continuous spectrum) The different
wavelengths of visible light (VIBGYOR).
- Full Spectrum - A complete spectrum with no breaks.
- Bright Line Spectrum-(Emission Spectrum) Specific
wavelengths of visible light emitted from a substance.
- Dark Line Spectrum - (Absorption Spectrum)
Specific Wavelengths of visible light a
- Spectral Classification of Stars - Stars are
classified by their unique spectral lines. Stars
have unique spectral fines mainly due to their
different temperatures.
Spectral Class
Effective Temperature
(K) M/MSun R/RSun
O 28,000 - 50,000 20 - 60 9 - 15
B 10,000 - 28,000 3 - 18 3.0 - 8.4
A 7,500 - 10,000 2.0 - 3.0 1.7 - 2.7
F 6,000 - 7,500 1.1 - 1.6 1.2 - 1.6
G 4,900 - 6,000 0.85 - 1.1
0.85 - 1.1
Spectral Class
Effective Temperature
(K) M/MSun R/RSun
K 3,500 - 4,900 0.65 - 0.85
0.65 - 0.85
M 2,000 - 3,500 0.08 - 0.05
0.17 - 0.63
L? <2,000
- Doppler Shift - The change in wavelength
associated with a moving object. If the object is
moving towards you the waves are compressed
and the wavelength is decreased due to the
objects forward motion (blue shift). If the object
is moving away from you, the waves are
separated and the wavelength is increased due
to the object moving away from you (red shift).
-
- Galactic Motion - observations of other galaxies based
on Doppler shift suggest that all objects in the universe are
traveling away from one central point. This has given rise to the Big Bang
theory, which describes that all matter and energy were at
one central point about 13 -15 billion years ago, and
exploded outward forming the universe as we know it.
Intelligent Life in the Universe
The Drake Equation – N = R* x fp x ne x fl x fi x fc x L
N = Number of Intelligent Civilizations in
the Milky Way Galaxy
R* = How many stars form per year in the
galaxy
fp = What percent of theses stars have
planets
ne = of these plants what percent would
harbor life
fl = of these planets what percent would life
be able to evolve
fi = of these planets what percent would
intelligent life be able to evolve
fc = of these planets what percent would
develop technology
L = How long would a technological society
last?