Download Final Exam Space Unit Review

S9 Space Notes
I. Our solar system
SOLAR SYSTEM MODELS
1) Geocentric or Earth-centered model:
Based on Aristotle’s ideas in 400 BC. He believed that
the Earth was the centre of the universe.
This theory was believed until 1500 AD!
• sun, moon, planets, and stars all rotate around the Earth
• the geocentric model held for almost 2000 years
Ptolemy used the idea of epicycles (pg. 364) (the idea that
planets move in mini circles while they orbit the Earth) to
explain why the planets sometimes changed their direction of rotation in the sky.
2) Currently accepted theory: Heliocentric model or Sun-centered model
• 1500’s Nicholas Copernicus created a model that has the sun at the centre of the universe
• all the planets orbit the sun and the stars are external to our solar system
• When Galileo designed a telescope that could look into space he found that Jupiter had 4 moons
around it. This helped disprove the geocentric model that said all bodies in the solar system
revolve around the Earth.
3) But there were still observations that the sun-centered model couldn’t explain. A
mathematician named Kepler figured out these problems mathematically: the sun is in the
center, but the orbits are elliptical not circular.
4) How do planets stay in stable orbits around the sun? NEWTON’S LAW OF UNIVERSAL
GRAVITATION which says “There is a gravitational force between all objects that pulls them
together.” Planets would just fly off through space in a straight line if no force acted on them.
The sun’s gravity pulls them towards the sun, and they go into an elliptical orbit – a balance
between moving straight and the sun’s gravity pulling them in.
5) Our Solar System
http://spaceplace.nasa.gov/solar-system-formation/en/ how our solar system was
formed
http://www.youtube.com/watch?v=DfkMJIvQOiI Inside our sun
http://www.youtube.com/watch?v=NABgdpZ2IPk NASA clip from Solar Dynamics
Laboratory (a satellite around the sun) – shows the roiling and boiling of the sun’s surface,
solar flares, sunspots
https://www.youtube.com/watch?v=F5JRVOw6mes Lunar eclipse
https://www.youtube.com/watch?v=Z7EY7PxZsnw Solar and lunar eclipse
http://www.teacherdomain/?q=lunar+and+solar+eclipse&fq_grade=PK&fq_grade=PS
II. Stars, Telescopes, EMR spectrum
1) Stars are made of mostly H and He. Our sun (sol) is 72% hydrogen. Stars emit their
own light from the high energy fusion of hydrogen atoms into helium.
2) Telescopes magnify and increase the resolving power (the detail you can see) of
objects. There are 2 types we will study; optical and radio wave telescopes. Telescopes use
waves from the EMR (Electromagnetic radiation) Spectrum to view celestial bodies.
Optical telescopes: use energy from LIGHT to view objects.
Galileo improved the 1st telescope (invented by Hans Lippershey) so that it could be used to
view space. His simple but amazing telescope magnified objects by using two lenses: the
objective lens (closest to the object you are looking at) and the ocular lens (closest to your eye).
Table 1. Three kinds of optical telescopes
reflecting telescopes
Most common. Can be very large. Have a ____________ for the
objective. Remember: mirrors REFLECT.
refracting telescopes
Have a ______ for the objective. Called a refracting telescope
because the lens bends (REFRACTS) the incoming light.
combinination telescopes Have a ________ at the front and an objective ___________ at the back.
(combine reflecting mirrors and refracting lenses).
☐ Study Fig. 5.14 p. 370. Incoming light from the object you are viewing comes in
from the left.
Further optical telescope advances
1. Combining Telescopes: Now powerful computers can combine images from 2 or more
telescopes (interferometry). The two separate telescopes act like one large telescope the size of
the total distance between the two telescopes! This provides great resolving power. The twin
Keck telescopes in Hawaii have such a high resolving power they can distinguish each headlight
on a car 800 km away! (p. 385)
2. Why do stars twinkle? Why is this a problem for astronomers? The Earth’s atmosphere
refracts starlight in random directions so astronomers can’t see stars clearly. How do
astronomers correct this problem? They use adaptive optics: computers process the images
and remove the blurring effect of the Earth’s atmosphere. The software “adapts” as the Earth’s
atmosphere changes.
3. What is light pollution? Why is this a problem for astronomers? Light pollution is the
glow in the sky at night caused by all the artificial lighting found in and around cities.
Astronomers can see only the brightest stars.
4. How do astronomers deal with air pollution? They locate telescopes in remote areas (i.e. up
north or on a mountain top).
Radio telescopes: use energy from RADIO WAVES. Radio telescopes are huge because radio
waves are so large. Visible light used in optical telescopes are often blocked by the huge
amounts of space dust. Radio telescopes solved this problem.
http://missionscience.nasa.gov/ems/emsVideo_02radiowaves.html
False colors (by computer enhancement) in radio telescope images indicate the intensity of
radio waves coming from an object.
Many radio telescopes are placed in VLA (Very Large Array) – Many radio telescopes are
connected into one very large to multiply their capabilities
EMR, Spectroscopy, star composition and movement
1) Scientists use the electromagnetic radiation (EMR) spectrum to learn a great deal about
the universe.
http://missionscience.nasa.gov/ems/emsVideo_01intro.html
Don’t forget! Wavelength measures the distance between two similar points on a wave,
and frequency is the measure of how many waves pass in a given time period
2) What are stars made of? Use a SPECTROSCOPE! A spectroscope uses visible light in the
EMR spectrum to determine the composition of stars.
Joesph von Fraunhofer (1820s) used a spectroscope to observe the Sun’s spectrum. He saw
dark lines in the spectrum called spectral lines but did not know what they meant. When an
element is heated and viewed through a spectroscope, that element will have a unique set of
spectral lines = an element’s signature or “fingerprint.” Early spectroscopes used prisms to
split the light. Now we use diffraction grating because they are more accurate.
By analyzing the spectrum of a star/sun we can
determine:
• What a star is made of
• the gases (atmosphere) surrounding a star
• which direction a star is moving (towards/away)
• how fast the star is moving
 Using the spectroscopes, look at different light sources (natural and man-made)
 Do Investigation 5-E pg. 381. “Long Distance Chemistry: Using Spectral Analysis to Identify
Star Composition. Answer Analyze questions 1 – 6. Defend your answer for #5.
 Do practice sheet “Analyzing Spectral Patterns BLM 5-10”
How does the EMR spectrum tell us how fast a star is moving and in what direction? Look at
the DOPPLER EFFECT!
DOPPLER EFFECT: Waves are compressed (shorter) in front of a moving object and stretched
out (longer) behind a moving vehicle. This effects color and sound.
http://www.youtube.com/watch?v=h4OnBYrbCjY the Doppler effect
• If a star is moving towards you its light waves get shorter, and the dark lines in its spectra shift
to the shorter wavelengths (the blue end) = we call this BLUE SHIFTED.
• If a star is moving away from you the dark lines shift to longer wavelengths = RED SHIFTED.
ROYGBIV!
III. Locating celestial objects (stars and planets) from Earth
How do we describe accurately where a celestial body is in the sky if that place is always
changing? We describe the position of a star/planet in the sky is described using altitudeazimuth coordinates
Altitude: angle above the horizon (i.e. “40o above the horizon” or “at an altitude of 40o”).
Altitude CANNOT be more than 90o.
Azimuth: angle clockwise from North, the direction we must face to see the star (i.e. 180oS or
“at an azimuth of 180oS). Azimuth coordinates MUST have degrees PLUS direction.
 Do the 3 practice problems on pg. 359 and the Alt-Azimuth Coordinates Practice Sheet (BLM 5Draw and label “altitude” and “azimuth” on the appropriate line for each star.
Learning check: A celestial object that is located 10o above the horizon in the northeast part of
the sky has an:
A. azimuth of 45o and an altitude of 10o
B. azimuth of 10o and an altitude of 45o
C. azimuth of 315o and an altitude of 10o
D. azimuth of 10o and an altitude of 315o
How Far is Far? Distances: LY (light year) and AU (astronomical unit) and triangulation
• since the solar system is so large we need a large unit of measurement, the astronomical unit:
1 AU is the distance from the Earth to the Sun = 150 million km
- the nearest star to the Earth is Proxima Centari, 272 000 AU
- The nearest galaxy to the milky way is Andromeda: 2 million light years away.
- The visible universe (from telescopes) has a diameter of 28 Billion light years
• But the universe is so much larger than our solar system, using AU outside our solar system is
impractical (it would be like using mm to measure distances across Canada). So astronomers
created the light year: the distance light travels in one year (63 240 AU).
• Light travels at 300 000 km/s. 1 light year = 9.5 trillion (9.5 x 1012) km. Calculate how
many light years Proxima Centauri is from Earth. ___________
• would you use AU or LY to measure how far
1) the moon is from the Earth
2) Mars is from the sun
3) Milky Way is from another galaxy
• Triangulation (parallax): estimates distance of a celestial body from Earth. Surveyors can use
it on earth to estimate distance of objects from a given point.
How do you do triangulation?
• You measure the distance of an object indirectly by making an imaginary triangle between the
observer and the object (i.e. star) whose distance you want to measure.
• Make a base line with the object to be measured in between the 2 points A and B. The larger the
baseline the more accurate the distance you calculate. Use the LONGEST baseline you can.
• Make a line from the two points to the object and measure the two angles
• Make a scale diagram (i.e. 1 cm = 10m) of the imaginary triangle to calculate the distance
Point A
baseline
Point B
Triangulating a Star: the diameter of the Earth is the baseline and we view the star from one
point on the Earth 6 months apart (i.e. in December and then again in June), lining up the star to
distant stars as the frame of reference.
 Do the practice sheet “Triangulation
Worksheet” #1 – 3. Hint for # 2: % error =
((calculated value – measured
value)/measured value) x 100.
IV. Reaching outer space! Rockets, probes, satellites
1) 3 parts of a rocket: tube, combustible material, payload
2) Combustible material (fuel) used by rockets:
a) solid: for shuttle launches: once ignited can’t turn it off
b) liquid: more complicated, more efficient because can control amount of
fuel entering combustion chamber so can stop or throttle. They have a
higher exhaust velocity than solid fuels. Check on this
c) Physics: For every reaction there is an equal and opposite reaction
d) gravitational assist “slingshot” method spacecraft use to get extra
acceleration in space
3) Probes: designed to explore celestial bodies beyond the Moon.
4) Shuttle: designed to transport equipment to the International Space Station and
other satellites, unique in that it was reusable.
5) Satellites: geosynchronous vs orbiting, how much area they can transmit over increases as go
further out (show with a flashlight), low earth orbit GPS (Global Positioning System) satellites
http://www.pbslearningmedia.org/resource/ess05.sci.ess.eiu.essatellites/earth-systemsatellites/ if this doesn’t work use this https://www.youtube.com/watch?v=mbDQSxUXefk
GPS http://www.youtube.com/watch?v=wi_3XwkA8cQ detailed
http://spaceplace.nasa.gov/gps-pizza/en/ simpler