unit 1 earth’s role as a body in space. lesson 1 you are here
TRANSCRIPT
Unit 1Unit 1
Earth’s Role as a Body in SpaceEarth’s Role as a Body in Space
Lesson 1Lesson 1
You Are Here You Are Here
Earth’s Position in SpaceEarth’s Position in Space
What is Earth’s position in the What is Earth’s position in the hierarchy of space?hierarchy of space?
Earth’s Position in the UniverseEarth’s Position in the Universe
Earth Earth Solar System (3Solar System (3rdrd planet from Sun) planet from Sun) Milky Way Galaxy (the Orion Arm) Milky Way Galaxy (the Orion Arm) Universe!Universe!
http://www.atlasoftheuniverse.com/
Earth’s Motion through Earth’s Motion through SpaceSpace
What is the cause of Earth’s What is the cause of Earth’s motion through space?motion through space?
The Origin of Our Expanding Universe
• The Big Bang Theory – The theory that the
universe began as a point and has been expanding ever since
• The 3 yellow galaxies in each model are…– Moving apart
en.wikipedia.org
The Origin of the Milky WayThe Origin of the Milky Way
Astronomers Astronomers hypothesize that the hypothesize that the galaxy began as… galaxy began as… Spherical clouds in Spherical clouds in
spacespace Newer stars have Newer stars have
orbits …orbits … lying in the plane of lying in the plane of
the disk around the the disk around the nuclear bulgenuclear bulge
http://www.google.com/imgres?imgurl=http://casswww.ucsd.edu/archive/public/tutorial/images/mw.jpg&imgrefurl=http://casswww.ucsd.edu/archive/public/tutorial/MW.html&usg=__
The Milky WayThe Milky Way
http://www.astropix.com/HTML/D_SUM_S/MILKYWAY.HTM
The Origin of the Solar SystemThe Origin of the Solar System
An interstellar cloud forms a solar system by… An interstellar cloud forms a solar system by… condensing as a result of gravity and becoming condensing as a result of gravity and becoming
concentrated enough to form a star and possibly concentrated enough to form a star and possibly planetsplanets
The shape and movement of a new solar system The shape and movement of a new solar system can be described as …can be described as … A rotating disk with a dense concentration at the A rotating disk with a dense concentration at the
centercenter
A solar nebula is…A solar nebula is… A disk of dust and gas that can form a starA disk of dust and gas that can form a star
The Eagle NebulaThe Eagle Nebula
http://nssdc.gsfc.nasa.gov/photo_gallery/photogallery-astro-nebula.html
Star formation has NEVER Star formation has NEVER been observed!been observed!
Lesson 2Lesson 2
The Third Rock from the Sun!The Third Rock from the Sun!
Think About It…Think About It…
How would Earth be different How would Earth be different if its orbit was more oval if its orbit was more oval
than circular?than circular?
Earth’s Orbit and Kepler’s Earth’s Orbit and Kepler’s LawsLaws
How do Kepler’s laws describe How do Kepler’s laws describe Earth’s orbit?Earth’s orbit?
Kepler’s Laws…Kepler’s Laws…
Johannes Kepler, Johannes Kepler, working with data working with data painstakingly painstakingly collected by Tycho collected by Tycho Brahe (from 1576-Brahe (from 1576-1601) without the aid 1601) without the aid of a telescope, of a telescope, developed three laws developed three laws which described the which described the motion of the planets motion of the planets across the sky. across the sky.
Unless otherwise noted, the info on the slides on Kepler’s laws was taken from the Unless otherwise noted, the info on the slides on Kepler’s laws was taken from the following website: http://hyperphysics.phy-astr.gsu.edu/hbase/kepler.htmlfollowing website: http://hyperphysics.phy-astr.gsu.edu/hbase/kepler.html
http://www.nmspacemuseum.org/halloffame/images.php?image_id=131
Kepler’s First Law…• The Law of Orbits: All planets move in elliptical orbits,
with the sun at one focus.• An ellipse is an oval shape that is centered on two
points instead of a single point. • The orbital period of a planet is the length of time it
takes for it to travel a complete orbit around the sun. (a year!)
Orbit Eccentricity…Orbit Eccentricity… The eccentricity of an ellipse can be defined as the ratio of the distance between the foci The eccentricity of an ellipse can be defined as the ratio of the distance between the foci
to the major axis of the ellipse. The more eccentric an orbit, the more of an oval it is.to the major axis of the ellipse. The more eccentric an orbit, the more of an oval it is. The eccentricity is zero for a circle. The eccentricity is zero for a circle. Of the planetary orbits, only Pluto has a large eccentricity.Of the planetary orbits, only Pluto has a large eccentricity.
http://solarsystem.nasa.gov/multimedia/display.cfm?IM_ID=175
Examples of Ellipse Eccentricity
Planetary orbit eccentricities
Mercury .206
Venus .0068
Earth .0167
Mars .0934
Jupiter .0485
Saturn .0556
Uranus .0472
Neptune .0086
Pluto .25
Kepler’s Second Law…• The Law of Areas: A line that connects a planet to the sun
sweeps out equal areas in equal times. • This empirical law discovered by Kepler arises from
conservation of angular momentum. • When the planet is closer to the sun, it moves faster,
sweeping through a longer path in a given time.
http://www.mathacademy.com/pr/prime/articles/kepler/index.asp
Kepler’s Third Law…• The Law of Periods: The square of the period of any planet
is proportional to the cube of the semimajor axis of its orbit. – P² = a³ – P = unit of time in Earth yrs, a = astronomical unit of length
• This law arises from the law of gravitation. Newton first formulated the law of gravitation from Kepler's 3rd law.
Barycenter and Earth’s Orbit…Barycenter and Earth’s Orbit…
The law of universal The law of universal gravitation states…gravitation states… that every pair of that every pair of
bodies in the universe bodies in the universe attract each other with attract each other with a force that is…a force that is…
proportional to the proportional to the product of their masses product of their masses andand
inversely proportional to inversely proportional to the square of the the square of the distance between them.distance between them.
Barycenter and Earth’s Orbit…
• A planet, such as Earth, actually orbits…– a point between it and the Sun called the
center of mass– This center of mass is called the barycenter.
http://www.barewalls.com/pv-605547_Barycenter-Diagram.html
Barycenter and Earth’s Orbit…
– http://spaceplace.nasa.gov/barycenter/
Lesson 3Lesson 3
The Third Rock from the Sun! The Third Rock from the Sun! (Continued)(Continued)
Think About It…Think About It…
How would Earth be different How would Earth be different if it did not rotate on its if it did not rotate on its
axis?axis?
Earth’s Rotation…Earth’s Rotation…
Day and night are caused by…Day and night are caused by…The rotation of the Earth on its axisThe rotation of the Earth on its axis
Earth spins…Earth spins…15 degrees each hour15 degrees each hour
There are There are 360360 degrees in a circle (the degrees in a circle (the circumference of Earth).circumference of Earth).
360 divided by 15 is 360 divided by 15 is 2424 so there are so there are 2424 hours in a day!hours in a day!
Earth’s Rotation…Earth’s Rotation…
The exact amount of time it takes Earth to The exact amount of time it takes Earth to spin one time on its axis is…spin one time on its axis is…23.9345 hours23.9345 hours
If an Earth day was 5832.5 hours long (like If an Earth day was 5832.5 hours long (like that of Venus!) then…that of Venus!) then… It would take 243 days for Earth to spin one It would take 243 days for Earth to spin one
time on its axis!time on its axis!Our day and night would be much longer! Our day and night would be much longer!
(It’d get really hot and really cold!)(It’d get really hot and really cold!)
Earth’s Rotation and Its Shape…
Earth’s rotation causes it to take the shape of an oblate spheroid.
As Earth rotates on its axis, centrifugal force causes the Earth’s mass to move away from its center at the equator where this force is greatest.
There is a slight bulging at the equator and a slight squishing at the poles.
See next slide!
Earth’s Rotation and Its Shape…
Simulation: http://www.cleonis.nl/physics/phys256/equatorial_bulge.php
Earth’s Rotation and Its Shape…
http://www.cleonis.nl/physics/phys256/equatorial_bulge.php
Earth’s Orbit and Seasons…Earth’s Orbit and Seasons…
The ecliptic The ecliptic is…is…the plane in the plane in
which Earth which Earth orbits around orbits around the Sunthe Sun
http://en.wikipedia.org/wiki/Ecliptic
Earth’s Orbit and Seasons…Earth’s Orbit and Seasons…• Remember, Earth’s axis is…Remember, Earth’s axis is…
– the imaginary line that cuts through the north and the imaginary line that cuts through the north and south poles. south poles.
– The tilt of Earth’s axis relative to the ecliptic is 23.5 The tilt of Earth’s axis relative to the ecliptic is 23.5 degrees. degrees.
http://republicanredefined.com/2010/03/02/chile-quake-shifted-earths-axis-and-made-days-shorter/
The Seasons!The Seasons!
http://www.exploratorium.edu/ancientobs/chaco/HTML/TG-shadows.html
The Seasons!The Seasons!
What causes summer in the northern What causes summer in the northern hemisphere? hemisphere? when it is tilted toward the Sun during Earth’s when it is tilted toward the Sun during Earth’s
orbitorbitWhat causes winter in the northern What causes winter in the northern
hemisphere?hemisphere?when it is tilted away from the Sun during when it is tilted away from the Sun during
Earth’s orbitEarth’s orbit
The Seasons!The Seasons!
The seasons in the northern and southern The seasons in the northern and southern hemispheres are…hemispheres are…opposites!opposites!
Lesson 4Lesson 4
The Man in the MoonThe Man in the Moon
Think About It…Think About It…
How would Earth be different How would Earth be different if it did not have a moon?if it did not have a moon?
The Moon’s orbit is tilted 5°…
http://earthsky.org/astronomy-essentials/what-is-the-ecliptic
Precession
Precession is… the wobble in Earth’s
rotational axis.
One full cycle of precession takes… 26,000 years!
The force that causes precession is… the sideways pull from the
Moon’s gravitational force on Earth.
Precession…
Our current north star is… Polaris
In about 12,000 years, our new north star will be… Vega
http://www.wwu.edu/skywise/a101_precession.html
A New North Star and Our Seasons…
Winters in the N. hemisphere will be…colder (Earth will be farthest from the Sun in
July – our new winter!)Summers in the N. hemisphere will be…
warmer (Earth will be closest to the Sun in January – our new summer!)
Next slide…
A New North Star and Our Seasons…
http://apollo.lsc.vsc.edu/classes/met130/notes/chapter16/precession.html
Tides…
Tides are…the periodic rise and fall of sea level.
High tide…Highest level to which the water rises
Low tide…lowest level of the water
Tides: Bay of Fundy…
http://www.srh.noaa.gov/jetstream/ocean/fundy_max.htm
http://www.amusingplanet.com/2012/03/tides-at-bay-of-fundy.html
Low Tide
High Tide
The Cause of Tides… Tides are caused by…
the gravitational attraction among Earth, the Moon, and the Sun.
The Moon and the Earth experience unbalanced gravitational and centrifugal forces due to the fact that they… orbit around their barycenter (Remember that word?!)
These forces generate… tidal bulges on opposite sides of Earth.
See next slide…
Tides…
http://mail.colonial.net/~hkaiter/Moon_Phases_Tides.html
Tide Simulation: http://astro.unl.edu/classaction/animations/lunarcycles/tidesim.html
Lesson 5Lesson 5
Twinkle, Twinkle, Our Big Star!Twinkle, Twinkle, Our Big Star!
Think About It…
Is it possible to make electricity by using the same energy that
powers the Sun?
A Little Bit About the Sun…
How many Earths could be lined up edge to edge to fit across the Sun?109
The Sun makes up…99% of the mass of the solar system!
A pair of dice with the density of the Sun…would weigh 2 pounds!
The solar interior is made of plasma.
The Sun’s Atmosphere…The Sun’s Atmosphere…
The Sun’s The Sun’s atmosphere consists atmosphere consists of…of…Photosphere… Photosphere…
the lowest layer the lowest layer 400 km thick400 km thickHot! (5800 K) Hot! (5800 K) the visible surface the visible surface
of the Sunof the Sunhttp://www.solarviews.com/images/VSS00031.jpg
The Sun’s Atmosphere…The Sun’s Atmosphere…
The Sun’s The Sun’s atmosphere consists atmosphere consists of…of…Chromosphere…Chromosphere…
Above the Above the photospherephotosphere
2500 km thick2500 km thickVery hot! (30,000 Very hot! (30,000
K)K)
The Sun’s Atmosphere…The Sun’s Atmosphere…
The Sun’s The Sun’s atmosphere consists atmosphere consists of…of…Corona…Corona…
Extends several Extends several million km from the top million km from the top of the chromosphereof the chromosphere
Very low density – Very low density – only visible during an only visible during an eclipseeclipse
Extremely hot! (1 to 2 Extremely hot! (1 to 2 million K)million K)
Solar Wind and Earth’s Solar Wind and Earth’s Magnetic Field…Magnetic Field…
Solar wind is…Solar wind is…A supersonic plasma that flows outward from A supersonic plasma that flows outward from
the corona at high speeds the corona at high speeds It consists of charged particles or ions It consists of charged particles or ions
Solar wind bathes each planet in a flood of Solar wind bathes each planet in a flood of high-energy particles. (Which isn’t very high-energy particles. (Which isn’t very good for us!)good for us!)
Next slide…Next slide…
Solar WindSolar Wind
Solar Wind and Earth’s Solar Wind and Earth’s Magnetic Field…Magnetic Field…
Earth’s magnetic field protects us from the Earth’s magnetic field protects us from the solar wind by…solar wind by…deflecting these particles and trapping them in deflecting these particles and trapping them in
two huge rings called the Van Allen beltstwo huge rings called the Van Allen belts
http://www.redorbit.com/education/reference_library/space_1/solar_system/2574610/van_allen_radiation_belt/
Earth’s Magnetic Field…Earth’s Magnetic Field…
The Auroras…The Auroras…
The auroras are created when…The auroras are created when…high-energy particles in the Van Allen belts high-energy particles in the Van Allen belts
collide with gases in Earth’s atmosphere collide with gases in Earth’s atmosphere which give off lightwhich give off light
See next slide…See next slide…
The Auroras…The Auroras…http://www.lovethesepics.com/2011/02/24-amazing-auroras-aurora-borealis-aurora-australis/http://www.lovethesepics.com/2011/02/24-amazing-auroras-aurora-borealis-aurora-australis/
Sunspots…Sunspots…
Sunspots are…Sunspots are… dark spots on the surface of the photospheredark spots on the surface of the photosphere
For sunspots to reach their maximum number in For sunspots to reach their maximum number in a solar activity cycle takes…a solar activity cycle takes… 11.2 years11.2 years
The absence of sunspots in the later half of the The absence of sunspots in the later half of the 1600’s caused the…1600’s caused the… Little Ice Age (Brrrrr!)Little Ice Age (Brrrrr!)
Fusion or Fission?Fusion or Fission?
• Fusion is…Fusion is…– the combining of lightweight nuclei (hydrogen) the combining of lightweight nuclei (hydrogen)
into heavier nuclei.into heavier nuclei.
• Fission is…Fission is…– The splitting of heavy atomic nuclei into The splitting of heavy atomic nuclei into
smaller, lighter atomic nucleismaller, lighter atomic nuclei
Fusion…Fusion…
Fusion occurs…Fusion occurs… in the stars!in the stars!
The two atoms that combine to form and The two atoms that combine to form and atom of helium are…atom of helium are…Hydrogen nuclei (deuterium and tritium)Hydrogen nuclei (deuterium and tritium)
Fusion…Fusion…
The mass that is lost when two hydrogen The mass that is lost when two hydrogen nuclei combine to form helium …nuclei combine to form helium …… … gets converted into energygets converted into energy
Albert Einstein’s theory of special relativity Albert Einstein’s theory of special relativity explains this!explains this!
http://www.nobelprize.org/nobel_prizes/physics/laureates/1921/einstein-bio.html
Fusion and Electricity Production…
“The power produced by a fusion reactor will be converted to electric energy or other goods like hydrogen or desalinised water.
Neutrons produced in the D-T fusion process carry 4/5 of the energy.
One or two fluids circulate in the blanket and in the diverter/FW to extract the energy and to provide stable operational temperature of the components.
The fluids must flow at high velocity (often in conditions of turbulent flow) while structural materials, pipes, junctions must withstand neutron bombardment, corrosion/erosion, high operational temperature, high heat flux.”
What??!!
http://www.isfrt-erice.enea.it/Page2.htm
Fusion and Electricity Production…
China claims fusion reactor test a success
Government hopes fusion provides clean, limitless energy source …
“BEIJING - Scientists on Thursday carried out China's first successful test of an experimental fusion reactor, powered by the process that fuels the sun, a research institute spokeswoman said.
China, the United States and other governments are pursuing fusion research in hopes that it could become a clean, potentially limitless energy source.
Fusion produces little radioactive waste, unlike fission, which powers conventional nuclear reactors.”
http://www.msnbc.msn.com/id/15043462/
updated 3:22 p.m. ET, Thurs., Sept. 28, 2006
Lesson 6Lesson 6
Twinkle, Twinkle, Our Big Star! Twinkle, Twinkle, Our Big Star! Continued…Continued…
Think About It…
What would happen to Earth if the Sun were turned off today?
The Electromagnetic Spectrum…
Electromagnetic radiation consists of … … electric and magnetic disturbances that travel
through space as waves. Electromagnetic radiation includes…
radio waves, microwaves, infrared energy, visible light, ultraviolet radiation, x-rays, and gamma rays
The electromagnetic spectrum… Organizes the forms of EM energy
EM energy… …is classified by wavelength and… … moves at the speed of light
The Electromagnetic Spectrum…
http://www.lbl.gov/MicroWorlds/ALSTool/EMSpec/EMSpec2.html
Energy Flows From the Sun…
http://virtualskies.arc.nasa.gov/weather/images/2b1.png
Energy Flows From the Sun…Radiation
the transfer of energy through space by visible light, ultraviolet radiation, and other electromagnetic waves
All substances that have temps over absolute zero emit radiation!
The hotter the substance, the shorter the wavelength.
http://ossfoundation.us/projects/environment/global-warming/earths-radiation-budget
Absorption of The Sun’s Energy by the Earth…
About 50% of incoming solar radiation is absorbed by the Sun.
Absorption of The Sun’s Energy by the Earth…
Which gas absorbs Which gas absorbs harmful ultraviolet harmful ultraviolet radiation from the radiation from the sun?sun?
OzoneOzone
http://mmedia.pl/ozone-layer-diagram-for-kids
Differential Heating…Differential Heating…
Which heats up and cools down more Which heats up and cools down more slowly?slowly?WaterWater
This is called differential heating.This is called differential heating.This is what tempers the climate in This is what tempers the climate in
coastal areas.coastal areas.
Photosynthesis…
http://abhsscience.wikispaces.com/Photosynthesis+TD
Food From the Sun!
http://wowk.images.worldnow.com/images/19108684_BG1.jpg