warm-up on your warm-up response sheet, answer the following question in complete sentences: what...
TRANSCRIPT
WARM-UP
On your Warm-Up Response Sheet, answer the following question in complete sentences:What season would you most easily find Orion?
Define constellation.
TUESDAY, SEPTEMBER 22ND Today’s Agenda: Today's Objective:
All About Constellations I will identify constellations and explain the role of Polaris in ancient and modern navigation (4C, 5C).
I will explain the historical origin of the constellations (4C,5C).
TUESDAY, SEPTEMBER 22ND
Planner Box
In Class: Constellations
Homework: Article Response - Stonehenge
Career Connection & Essential Questions
Boat Captain - $102,500 / yr
What are the major constellations and stars in
the night sky?
REGRADE CONSTELLATION GRAPHING (PG. 17)
12 Constellations = 2 pts each 12 Labeled Constellations = 1 pts each 12 Color-Coded Constellations = 2 pts each 10 Stars Labeled = 2 pts each 10 Stars Highlighted = 1 pts each Glued in = 10 pts Total points possible = 100 Write their score OUT OF 100
Title: ConstellationsEQ: What are the major constellations and stars in the night sky?
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Objective: All students will identify the major constellations and stars in the night sky and explain how they are used for navigation.
Constellation:a constellation is a specific area of the celestial sphere as defined by the International Astronomical Union (IAU)
Notice the Big Dipper rectangle opens out…
The Little Dipper rectanglepoints inwards!
Polaris• Polaris - the star's current distance from the exact North Pole of the sky is the width of 1 ½ full moons. It is used for navigation.
• (Called the North Star)• From the zenith (straight above your head) to the North Star is due north
Constellations by Season
SPRING SUMMER AUTUMN WINTER
Virgo Sagittarius Pisces GeminiLibra Capricorn Aries Cancer
Scorpio Aquarius Taurus LeoCassiopeia OrionAndromeda Ursa Major
Ursa MinorCanis Major
Constellation Name – “Nick Name”
(Season)
PICTURE
The Myth:
• http://www.astromax.org/con-page/• www.ianridpath.com/startales/
contents.htm
Outside
Inside
RIGHT NOW:Take a marker and trace
the stars’ locations for each of the
constellations so you recognizethe pattern.
Puzzle ShareOne minute per constellation (16 constellations = 16 minutes)
• Zodiac constellations are on the ecliptic in the night sky.
Get out a sticky note, write your name on it at the top, and number #1-
#5.
DOL #1 Which constellation would this be?
DOL #2 Which constellation would this be?
DOL #3 Which constellation would this be?
Ursa Major
DOL #4 Which constellation would this be?
Ursa Major
DOL #5 Which star does this point to, and what is its significance?
Checking Our Work
1)Orion2)Scorpio (Scorpius)3)Cassiopeia4)Ursa Major5)Polaris, which is the North Star
MasteringAstronomy.com• Log in with the user name you created in class.• Click on “Assignments” tab.• Choose “Navigation and Stars” assignment.• You may work in partners (which means 2, not
3) but you are each being graded for your responses. I receive the grades as soon as you input your answer. There are 2 parts.
• Both sections need to be completed before the last 15 minutes.
4C/5C Quiz - Constellations
►http://goo.gl/forms/8mtXefhi2W
HOMEWORK: DUE THURSDAY.
Article Response – Find an article explaining Stonehenge’s significance as it relates to constellations and/or navigation.
Write your source & a 2-3 sentence summary.
WARM-UP
On your Warm-Up Response Sheet, answer the following question in complete sentences:What is the difference between a light year and an AU?
What constellation tells you where the North Star is? What is the real name of the North Star?
THURSDAY, SEPTEMBER 24TH Today’s Agenda: Today's Objective:
Apparent vs. Absolute Brightness
Inverse Square Law
I will explain the relationship between absolute and apparent brightness (magnitude) to the distances of celestial objects (4C,5C).
THURSDAY, SEPTEMBER 24TH
Planner Box
In Class: Inverse Square Lab
Homework: Finish Post-Lab Discussion Questions
Career Connection & Essential Questions
Astronomer - $104,000 / yr
How are apparent and absolute brightness of a celestial object related?
Apparent Brightness and Distance of Stars
EQ: How are apparent and absolute magnitude of celestial objects related to their distance?
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Appearances can be deceiving…
Does a star look "bright" because it is intrinsically very luminous?
Does a star look "bright" because it is intrinsically faint but located nearby?
To know for sure, you must know either the distance to the star, or some other, distance-independent property of the star that clues you in.
APPARENT BRIGHTNESS LAB
Apparent Brightness of Stars
How bright a star appears to be will depend upon:How bright it is physically (Luminosity)How far away it is (Distance).
POST-LAB DISCUSSION
The luminosity of light is the power (energy per second) per area. Since the energy that comes through the hole you cut is constant but spreads out over a larger area, the brightness (or intensity) of light decreases. Since the area increases as the square of the distance, the brightness of the light must decrease as the inverse square of the distance. Thus, brightness follows the inverse-square law.
If you had two light bulbs and knew that they both give off the same amount of light (same luminosity/power), then you could calculate the relative distance between the two of them simply by measuring their relative brightness. If you also knew what the luminosity/power of the bulbs was, you would then be able to determine the distance to both bulbs. Or, if you knew the distance to one of the bulbs you could determine the distance to the other one.
POST-LAB DISCUSSION
This is how astronomers use the inverse square law of light to measure distances to stars or galaxies. They find stars that are the same kind (same size and temperature) and, therefore, have the same luminosity. They measure the brightness of the stars and can determined distances if they know either what the luminosity of the stars is or the actual distance to one of the stars by some other method.
Cepheid variable stars are particularly useful in determining astronomical distances. Cepheids are stars whose brightness increases and decreases in a regular period of time. Because the relationship between brightness and period is standard, if the variability period is known then the brightness can be inferred. Once the brightness of the star is known, its distance can be calculated by comparing it to another Cepheid star. Thus, Cepheid variables act as the “standard candles” of astronomical distances.
Henrietta
Leavitt
Apparent Brightness of StarsInverse Square Law of Brightness relates the Apparent Brightness of a star (or other light source) to its Luminosity (Intrinsic Brightness)
Absolute Magnitude System
Absolute magnitude of a star is its brightness seen from a distance of 10 parsecs.What’s a parsec?
Absolute Magnitude System
The modern system of absolute magnitudes defines them as: Bigger magnitude
= fainter star.The standard of brightness is the
star Vega (0th magnitude)
Apparent Magnitude System
(Same for apparent magnitudes: bigger magnitude = fainter appearance)
Modern Magnitude System
Examples:10th mag star is 100x fainter than a 5th mag star.20th mag star is 10,000x fainter than a 10th mag
star.Faintest stars measured this far are ~30th
magnitude.
For Example…
Star A and star B both have an absolute magnitude of 2.0, but star A has an apparent magnitude of 5.0 and star B has an apparent magnitude of 7.0. Describe the relationship of their absolute brightness.
TO FIND THE DISTANCE…
The value of the distance modulus (apparent minus absolute magnitude) can give us a rough estimate of the star’s distance:
If “m – M = 0”, then the distance is exactly 10 pc
If “m – M < 0”, then the distance is closer than 10 pc
If “m – M > 0”, then the distance is farther than 10 pc
