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Welcome to Earth Science! Unit 6. What is Astronomy?. Astrology.

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  • The study of celestial objects, spaceand the universe. EX. moons, planets, stars, nebulae, and galaxies. Includes the physics, chemistry, mathematics, and evolution of these objects, and phenomena that originate outside the atmosphere of Earth.
  • Ex. supernovae explosions, gamma ray bursts, and cosmic background radiation.
what is a theory
What is a Theory?

Once a hypothesis has been tested multiple timesand generally accepted, it may lead to the development of a theory.

A theory is a hypothesis or a set of hypothesis that is supported by the results of significant experimentation and observation.

light and the doppler effect
Light and the Doppler Effect
  • In 1665, Isaac Newton observed that sunlight passing through a glass prism produced a rainbow of colors: red, orange, yellow, green, blue, and violet.
  • Newton named this display of colors the spectrum.
light and the doppler effect1
Light and the Doppler Effect
  • He determined that light travels in waves.
light and the doppler effect2
Light and the Doppler Effect
  • The distance from the crest of one wave to the next is a wavelength.
  • Each color in the spectrum has a different wavelength.
  • Red has the longest wavelength
  • Violet has the shortest wavelength.
light and the doppler effect3
Light and the Doppler Effect

When a light source is moving toward an observer, the wavelengths of the light produced are shorter

When a light source is moving away from an observer, the light waves produced are longer.

doppler effect
Doppler Effect

Higher Frequency

Lower Frequency

light and the doppler effect4
Light and the Doppler Effect

The shift in the wavelengths of energy emitted by an energy source moving away from or toward an observer is called the

Doppler Effect.

light and the doppler effect5
Light and the Doppler Effect
  • Scientists have been making observations for hundreds of years.
  • They continue to observe movement of red shaded galaxies. This is known as the “ Red Shift”
what does that mean
What does that mean?

Check it!

  • Which way is the galaxy moving?
    • Put up a fist if you think the galaxy is moving away from Earth.
    • Put up a five if you think the galaxy is moving toward Earth.
big bang theory
Big Bang Theory
  • The “Red Shift” is the biggest evidence for the Big Bang Theory.
  • The Big Bang Theory establishes that the universe is expanding (which can be seen through the red tint of galaxies).
the big bang theory
The Big Bang Theory
  • As the cloud expanded, some matter clumped together to form galaxies
  • The universe is continuously expanding and moving apart from one another
  • This theory also hypothesizes when time began:

period of extreme and rapidexpansion about13.7 billion years ago.

big bang theory lt 3 14
Big Bang Theory LT#3/14


  • This theory is supported by the fact that it provides explanation for observations of distant galaxies receding from our own; of the measured composition of stars, earthly gases, and residual radiation that still fills the universe.
  • Scientists use information from amounts of radiation AKA radiometric dating to calculate the age of meteorites, moon rocks, and Earth’s oldest minerals.
big bang and nucleosynthesis
Big Bang and Nucleosynthesis
  • The Universe's light-element abundance is another important criterion by which the Big Bang hypothesis is verified.
  • The cosmic formation of elements more complex than the hydrogen.
  • Light elements (namely deuterium, helium, and lithium) were produced in the first few minutes of the Big Bang.
  • Heavier elements originate in the interiors of stars which formed much later in the history of the Universe.
  • Taken place between approximately 10 seconds until 20 minutes after the Big Bang, and is calculated to be responsible for the formation of most of the universe's helium.
evolution of the universe
Evolution of the Universe

Cosmic Evolution

Formation of Milky Way

Formation of Earth

Origin of Matter


Big Bang

what is a star lt 4
What is a star? LT#4
  • A star is a body of gases that gives off a tremendous amount of radiant energy in the form of light and heat.
  • All life on Earth is dependent on the Sun, the star closest to the Earth. This is because the sun provides a critical forms of energy:

light and heat

importance of stars
Importance of Stars
  • This is important to life on Earth because:
    • Plants need light to perform photosynthesis and make energy.
  • We need a certain temperature for life to occur (Venus & Mars=no life)
      • Why?
development of a star
Development of a Star
  • Stars go through a sequence of developmental stages:
    • They are formed; evolve in size, mass, and brightness; and eventually burn out.
  • Astronomers classify stars according to their color (spectral type), composition (elements), and temperature.
structure of the sun
Structure of the Sun
  • The Sun is a medium-sized star about halfway through its predicted life span of about 10 billion years.
  • What will happen when the Sun burns out?
    • Life on Earth will end?
    • Sun will explode, supernova, and left over material will form a new star and planetary systems.
  • The sun has three basic regions:
    • The core
    • The inner zones
    • The atmosphere
the core
The Core
  • The core is the center of the sun
    • Makes up 10% of the sun’s diameter
  • The temperature of the core is about 15,000,000 degrees Celsius
    • No liquid or solid can exist at that temperature, so it is purely gas
the core lt 5
The Core LT# 5
  • The sun’s mass is 300,000 times the earth’s mass.
  • Therefore the force of gravity is much greater and the center is very dense.
  • There is constant nuclear fusion happening within the sun’s core.
nuclear fusion energy
Nuclear Fusion = Energy!
  • Nuclear fusion produces energy in the sun’s core that will reach Earth and be used to sustain life on Earth.
  • Does three things:
  • Converts hydrogen into helium (or rather, makes helium nuclei from protons)
  • Converts mass to energy.

Fusion of hydrogen helium

  • This energy causes the sun to shine
who discovered that mass changes to energy lt 8
Who discovered that mass changes to energy? LT#8
  • Albert Einstein
    • Theory of relativity
    • A lot of energy can come from little mass
    • E = mc2
    • Tells us that the energy (E) generated equals the mass lost (m) times the speed of light squared (c2).
    • Approximately half of a billion tons of hydrogen is being converted into helium each second.

That’s a lot of ENERGY!!!

fusion lt 5
Fusion LT#5
  • Video: http://www.youtube.com/watch?v=pusKlK1L5To
  • The reactions produce high-energy photons (gamma rays) that move through the "radiative layer" surrounding the core.
  • Nuclear fusion within stars produces all elements lighterthan and including iron, and the process releases the energy seen as starlight.
  • Heavier elements are produced when certain massive stars achieve a supernova stage and explode.
  • The cooler areas of the sun will appear darker than the areas surrounding them
  • Cool, dark areas of gas within the photosphere that are caused by powerful magnetic fields are called sunspots
sunspot cycle
Sunspot Cycle
  • Sunspots initially appear in groups about midway between the sun’s equator and poles
  • As they slowly disappear, new ones appear near the suns equator
  • The cycle is usually about 11 years long
  • The magnetic fields that cause sunspots also create other disturbances
  • One of these disturbances are great clouds of glowing gases, called prominences
  • These form huge arches that reach high above the sun’s surface
    • These can arch over 300,000 miles above the surface
    • These can last for several weeks, while others can exist for up to a year
solar flares
Solar Flares
  • One of the most violentof all solar disturbances would be a solar flare
  • A solar flare is a sudden outward eruption of electrically charged atomic particles
    • They can extend up to several thousand miles within minutes
    • They are usually less than an hour in length
    • They occur near sunspots, and at a peak in the sunspot cycle, can have between 5 and 10a day
magnetic storms
Magnetic Storms
  • Some particles from a solar flare are flung out with so much force that they escape into space
  • As the gusts of solar-wind particles enter the atmosphere of the earth, they can disturb the Earth’s magneticfield
  • This disturbance is called a magnetic storm
    • These can interfere with radio communications on Earth
    • The average occurrence is less than one per year
  • Bands of light seen in the sky from earth due to magnetic storms
  • The electrically charged particles of the solar wind strike the gas particles in the upper atmosphere, producing green, red, blue or violet sheets of light
    • These are also callednorthernlights or southern lights
    • More commonly seen in the polar regions of the earth and sometimes at the equator
  • Mercury is the planet closest to the sun
  • Therefore, Mercury has a shorter orbit period than any other planet- 88 days
  • It rotates very slowly on its axis – once every 59 days
  • It is so close to the sun that light from the sun usually obscures the planet from view
  • Mercury has no moons
  • The second planet from the sun is Venus
  • The orbit of Venus is 225 days, although it also rotates very slowly-once every 243 days
  • The direction of rotation is opposite that of the other planets
    • This is the only planet in which the sun rises in the west and sets in the east
  • Venus also has nomoons
  • The third planet from the sun is Earth
  • The orbit period for Earth is 365.24 days, completing one rotation in 23 hours and 56 minutes
  • Earth is the 5thlargest planet
  • Earth has one moon
earth where life exists
Earth: Where Life Exists!
  • Life is able to exist on Earth because of the distance from the sun
    • The temperature is warm enough for water to exist as a liquid
      • Mercury and Venus are too close to the sun, therefore water evaporates
      • Mars and the other planets are so far that most of the water is in the form of ice
  • Mars is the fourth planet from the sun
  • Its orbit period is 687 days and its rate of ration is 24 hours, 37 minutes
      • The length of day on Mars and Earth are almost the same
  • Mars also has seasons like Earth because of the tilt of its axis
  • Mars has two moons
  • The first of the outer planets, 5th from the sun
  • The largest planet in the solar system
    • Its mass is two times that of the other eight planets combined
  • Its orbit around the Sun is 12years
  • Jupiter rotates faster than any other planet – every 9 hours and 50 minutes
  • Jupiter has 17moons and 4rings
  • The 6th planet from the sun
  • Saturn is about half a billionmiles fartherfrom the sun than Jupiter
  • The secondlargest planet
  • The average temperature is -284 degrees
  • Saturn has 18 moons and several rings
  • The 7th planet in the solar system
  • The thirdlargest planet
  • Uranus is the firstplanet to have been discovered
  • Uranus has 20 moons and at least 11small rings
  • Its orbit around the sun is almost 84 years
  • The 8th planet from the sun
  • Neptune is similar to Uranus in size and mass
  • Its orbit is 164 years and rotates every 16 hours
  • Neptune has 8 moons and 4rings
dwarf planets
Dwarf Planets
  • If the sun were as tall as a typical front door, Earth would be the size of a nickel and dwarf planets Pluto and Eris, for would each be about the size of a tip of mechanical pencil led!
  • Dwarf planets orbit the sun, a star.
  • Most are located in the Kuiper Belt, a region of icy objects beyond the orbit of Neptune.
  • Pluto, one of the largest and most famous dwarf planets, was once considered a planet (2006).
  • Discovering new dwarf planets all the time.
  • To honor Pluto, all dwarf planets that orbit the sun beyond Neptune are called plutoids (not dwarf planets).
dwarf planets1
Dwarf Planets
  • Dwarf planet Ceres is in the main asteroid belt between Mars and Jupiter.
  • Days and years vary on dwarf planets. One day on Ceres, for example, takes about nine hours (the time it takes for Ceres to rotate or spin once). Ceres makes a complete orbit around the sun (a year in Ceresian time) in about 4.60 Earth years.
  • Dwarf planets are solid rocky and/or icy bodies..
  • Many, but not all dwarf planets have moons.
kuiper belt the oort cloud
Kuiper Belt & the Oort Cloud
  • The Kuiper Belt and the Oort Cloud orbit around the Sun.
  • Contain many comets, asteroids, and other small bodies made largely of ice.
  • The Kuiper Belt is a doughnut-shaped ring, extending just beyond the orbit of Neptune.
  • Long-period comets (which take more than 200 years to orbit the sun) come from the Oort Cloud. Short-period comets (which take less than 200 years to orbit the Sun) originate in the Kuiper Belt.
Oort Cloud

Long-period comets

> 200 year orbit


Kuiper Belt

Short-period comets

<200 year orbit

moons orbit a round planets
Moons: Orbit Around Planets
  • A moon is any natural satellite (as opposed to a human-made satellite) that orbits a planet.
  • They are generally solid bodies, and few have atmospheres.
  • Astronomers have found at least 146 moons orbiting planets in our solar system.
  • Another 28 moons are awaiting official confirmation of their discovery.
  • This number does not include the six moons of the dwarf planetsor tiny satellites that orbit some asteroids and other celestial objects.
  • In the terrestrial (rocky) planets of the inner solar system:
    • Mercury and Venus have nomoons at all, Earth has one and Mars has twosmall moons.
  • In the outer solar system, the gas giants Jupiter and Saturn and the ice giants Uranus and Neptune have numerous moons.
planets and moons
Planets and Moons

The asteroid belt is a region of space between the orbits of Mars and Jupiter where most of the asteroids in our Solar System are found orbiting the Sun.

johannes kepler orbits
Johannes Kepler& Orbits

Johannes Kepler created three laws of planetary motion:

  • The orbits are ellipses
  • NOT circles
      • With Sun at one focus
  • Equal areas in equal times
    • A planet’s speed varies as it moves around its elliptical orbit
    • The orbital period of a planet is related to the size of its orbit
kepler s second law
Kepler’s Second Law
  • Describes the fact that a planet moves fastest in its orbit when it is nearest the Sun.
  • If you imagine a line connecting the planet and the Sun, the line sweeps out equal areas in equal times.
  • Area A = Area B = Area C

Maximum speed

Decreasing speed

Minimum speed

kepler s second law2
Kepler’s Second Law
  • Perihelion = point in orbit nearestto sun
  • Aphelion = point in orbit furthest from sun
kepler s third law
Kepler’s Third Law
  • The further a particular planet is from the sun, the longer its period (time) of revolution.
  • 1. Farther planets have longer orbital paths
  • 2. Farther planets have slower orbital paths
sir isaac newton
Sir Isaac Newton
  • Newton’s Laws of Gravity

First Law

    • All objects with mass will be acted on by gravity and will pull all other objects with a certain gravitational force.
newton s laws of gravity
Newton’s Laws of Gravity

Newton’s Second Law

The mass (weight) of an object will determine the amount of gravitational forcethat object possesses. The greater the mass, the greater the gravitational force.

newton s law of inertia
Newton’s Law of Inertia

States that an objects motion will not change unless that object is acted on by an outside force.



Stable Orbit

gravity and inertia orbit
Gravity and Inertia= Orbit
  • Inertia – causes a planet to move in a straight line.
  • Gravity – pulls a planet toward the sun.

Earth’s Direction of Rotation:


Angular Rate of Rotation:

THINK – one complete rotation

360degrees in 24hours

Rate= 3600/24 hours = 150/hour

  • The orbiting of one celestial body around another celestial body. EX. Earth orbits around the Sun!
  • Earth’s Angular Rate of Revolution

1. 360 degrees

2. 365 days

3. Rate = 3600/365 days ~ = 10/day

effects of earth s revolution
Effects of Earth’s Revolution
  • Nighttime constellations change in a yearly cycle.
  • Constellation– groups of stars that form patterns of imaginary things such as animals, legendary heroes, and mythological gods
  • Zodiac– a band of 12 constellations that forms a background for the Sun as seen from the revolving Earth
  • Revolution + Earth’s Tilt = Seasons!
winter solstice
Winter Solstice
  • Northern Hemisphere tilted away from the sun
  • Occurs around December 21
  • Sun overhead at 23.5°S (declination); Tropic of Capricorn. This is the
  • location that has the sun's rays striking the earth at a right angle or perpendicular to the surface on this day.
  • Latitudes south of 66.5°S (South Pole) have 24 hrs daylight; latitudes north of 66.5°N(North Pole) have 24 hrs darkness
  • Daylengthincreases from 0 hours from the N. Pole to the Arctic circle, to 12 hours at the equator, to 24 hours at the Antarctic Circle (and down to the S. Pole).
summer solstice
Summer Solstice
  • Northern Hemisphere tilted toward the sun
  • - Occurs around June 21
- Sun overhead at 23.5°N (declination); Tropic of Cancer. This is the location that has the sun's rays striking the earth at a right angle or perpendicular to the surface on this day.
- Latitudes north of 66.5°N(North Pole) have 24 hrs daylight; latitudes south of 66.5°S (South Pole) have 24 hrs darkness
  • - Daylength increases from 0 hours from the S. Pole up to the Antarctic Circle, to 12 hours at the equator, to 24 hrs at the Arctic circle (and all the way up to the N. Pole)
the equinoxes
The Equinoxes
  • Vernal (Spring) and Autumnal (Fall)
  • Typically occur March 20 and September 22
  • Sun is over the equator
  • All points all over the

world have about

12 hours of daylight

and 12 hours of night

rotation vs revolution
Rotation vs. Revolution



Movement of Earth around the sun

Once a year

1 degree of orbit/day

Causes seasons and length of day/night

Proof: Parallax (apparent movement of the stars)

  • Movement of Earth around its axis
  • Once a day
  • 15 degrees longitude/hour
  • Causes night and day
  • Proof: Foucault's Pendulum and


earth s place in the universe
Earth’s Place in the Universe

Light Year

  • The distance light travels in one (1) year.
  • 6,000,000,000,000 miles (6.0 x 1012)
  • The speed of light is 186,000 mi/sec.
  • We see all night stars as they WERE when the light left that star.
    • When we look at distant stars and galaxies, we look back in time.
the milky way galaxy
The Milky Way Galaxy
  • Our sun is only one of the estimated 180 Billionstars that make-up the Milky Way Galaxy.
  • The Milky Way is aSpiralgalaxy.
lunar orbit
Lunar Orbit
  • The orbit of the moon around the earth forms an ellipse, not a circle
    • This makes the distance between the earth and its moon vary
      • When the moon is furthest from the earth, it is at apogee
      • When the moon is closest to the earth, it is at perigee

The Moon has a rotational period of 27.3 days

lunar rotation
Lunar Rotation
  • In addition to orbiting the earth and revolving around the sun, the moon also spins on its axis
    • It spins very slowly, completing a rotation only once during each orbit around the earth
    • Because the rotation and revolution of the moon take the same amount of time, observers on earth always see the same side of the moon
  • An eclipse occurs when one planetary body passes through the shadow of another
  • When the moon is between the earth and the moon, there can be a total or a partial solareclipse
solar eclipses
Solar Eclipses
  • Solar eclipses onto are seen by people in one part of the earth in particular
  • Because the earth rotates, total solar eclipses never last more than seven minutes in a single location
lunar eclipses
Lunar Eclipses
  • Lunar eclipses occur when the earth is between the moon and the sun
phases of the moon
Phases of the Moon
  • New Moon Phase
    • When the moon is between the sun and the earth, the side of the moon facing the earth is unlighted
    • During the new moon phase, there is no area of the moon visible from the earth
phases of the moon1
Phases of the Moon
  • Waxing-crescent phase
    • As the moon orbits around earth, part of its lighted half is visible
    • When the visible portion of the moon increases, it is said to be waxing
    • When a sliver of the moon is visible from the earth, it enters this phase
phases of the moon2
Phases of the Moon
  • First Quarter Phase
    • When the moon has moved through one quarter of its orbit
    • It looks like a semicircle and half of the lighted side of the moon is facing the earth
phases of the moon3
Phases of the Moon
  • Waxing-Gibbous Phase
    • When the visible portion of the moon is larger than a semicircle and still increasing
phases of the moon4
Phases of the Moon
  • Full Moon Phase
    • This is when the moon appears as a full circle
    • This is when the earth is between the sun and the moon and the entire half of the moon reflecting the light of the sun is visible from earth
phases of the moon5
Phases of the Moon
  • After the full moon, the portion of the moon visible from earth decreases; this is called waning
    • Waning-gibbous is larger than a semicircle, but is decreasing
    • Last-quarter is when it is only a semicircle yet again
    • When only a sliver is visible, it enters the waning-crescent phase
    • The entire sequence starts over