Project/Experiment #1--The Sun

FREDERICK COMMUNITY COLLEGE

The Planets and the Solar System

The Sun Project

Directions:  Below are three different Project choices that you can complete for the Sun Project.  Please read over the directions and notes for each project carefully and complete one of the three projects listed.

The Sun Project will be Due in class on Friday, February 17th, 2012

Project Choices:

IMPORTANT NOTE:  Watch the News for the week’s weather.  These projects MUST be completed on a completely Sunny Day!!!!!

Project #1:  A Sundial

This experiment asks the question: Can the sun tell time? For elementary students, this project demonstrates how the sun can assist them in telling the time of day. You will need a stick about 12 inches long, a mound of play dough, a watch and small stones. You will also need a sunny day to complete the project. Ball up the mound of play dough and push the stick into it so that the stick stands up in the play dough. Place the play dough and stick on a sidewalk. Now look at your watch and mark the time. Look at the shadow that the stick makes on the sidewalk and place one of the small stones on the shadow and note the time of day that the shadow indicates. Every hour go back and look at the stick and the shadow and place another stone for each hour of the day on your sundial.

Read more: Fun Science Projects About the Sun | eHow.com http://www.ehow.com/list_5783058_fun-science-projects-sun.html#ixzz1BhqAeRgp

Notes:  You don’t have to build your sundial like it is described here.  You may construct your sundial creatively with different materials. 

Due in Class:  Your Homemade Sundial and a picture of the stone clock that the sun created for you.

Time Length:  Begin Making the clock at 8 Am in the morning and finish the clock on the same day at in the afternoon.  Every hour mark the position of the Sun’s shadow with a new stone.

Project #2:  Radiant Energy

This project can be performed by individual students, groups or used as a class experiment. The purpose is to determine if the sun is capable of producing heat inside of a bottle. You will need at least two bottles with corks, a thermometer, water and a variety of materials to cover one of the bottles, such as aluminum foil, cloth or plastic wrap. Cut a hole in the corks so that the bottom of the thermometer can be inserted through the hole. You should be able to see the bottom of the thermometer through the bottle. Fill both bottles with water, leaving enough space for the bottom of the thermometer at the top so that it does not touch the water. First set the two bottles in the shade for an hour and record their temperatures. Then cover one of the bottles with one of the materials you have selected and leave one uncovered. Set the bottles in direct sunlight, wait an hour and record the temperatures. Continue recording the temperatures after covering the test bottle with different materials and compare those temperatures with the temperature of the bottle that has not been covered. Take pictures to demonstrate your process and record your findings for the experiment.

Read more: Fun Science Projects About the Sun | eHow.com http://www.ehow.com/list_5783058_fun-science-projects-sun.html#ixzz1BhrCwpVG

Notes:  In this project, you must be precise with your recordings.

Due in Class:  Record Log showing your temperatures of each bottle after each hour.  Time Length:  From 8 Am to to complete this project.

Project #3:  Can the Sun Distill Water?

This project demonstrates how the sun can change salt water into drinking water. You will need a large bowl, salt, water, a glass that is shorter than the rim of the bowl, plastic wrap and an object to weigh down the plastic wrap on top of the glass. You may also need tape if the plastic wrap does not cling well. Pour water into the bowl so that it covers about 2 inches over the bottom of the bowl. Put a tablespoon of salt in the water and stir the water until the salt dissolves. Now set the glass in the middle of the bowl so that it stands upright and cover the bowl with plastic wrap. If the plastic wrap will not stick to the sides of the bowl, hold it down with tape. Find an object that will cover the top of the glass, weigh down the plastic wrap and place it over the plastic wrap on the glass. Now make a hypothesis about whether or not the sun can remove the salt from the water. Students can wait from one to eight hours to check on the project. When they do they should find salt in the bowl and clean drinking water in the glass. A taste test will prove the findings.

Read more: Fun Science Projects About the Sun | eHow.com http://www.ehow.com/list_5783058_fun-science-projects-sun.html#ixzz1Bhrrzh6M

Due in Class:  Pictures of the Project and an answer to the question Can the Sun Distill Water?  Must provide reasons as to how this happens.  You will need to do a little Internet or Book research in order to answer this question completely.
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To Help you with this project, here are some Basic Properties of Stars:

Astronomy Notes

Part 10: Basic Properties of Stars

John P. Pratt

Visual Observations

Names
  • The brightest stars have names, generally of Arabic origin.
  • They also are designated by the Greek letters, like alpha, beta, gamma, followed by the name of the constellation.
  • The Greek letters are usually in order of brightness, so brightest is usually alpha.
  • For example, the star Sirius is alpha Canis Majoris (brightest in Big Dog, Canes Major).
  • You should memorize all 15 of the brightest stars visible from your location.
Looking at Stars
  • All stars are so far away that they appear thousands of times smaller than a pinpoint.
  • They look a lot bigger than they are because the light triggers one cell in your eye, which is the smallest thing you can see.
  • Stars twinkle because as the narrow beam of light traverse the air, it can bend and miss your eye.
  • If you are using a telescope, try picking a night when the stars do not twinkle much. Called good "seeing."
  • You can see dim stars by looking several degrees away from them, using peripheral vision, because the place in your eye that focuses best is not the most sensitive to light.
  • Several stars are bright enough to see their actual colors, especially as red, orange, yellow, white and blue.
Photographs of Stars
  • Bright stars make big images in photos, but that image is not a picture of the star.
  • A big star image is formed because the light gets smeared out in a circle.
  • The rays sometimes seen coming from stars in photos are images of the secondary mirror supports.
  • The rings and disks around stars images are caused by diffraction.
  • Astronomers do not use photographs much to measure star properties.
  • Some colors in photographs are not accurate, but a caused by film failures. The Orion Nebula looks red in photos (from Hydrogen's H-alpha line) but looks green to the eye (from Oxygen).
Distances
  • The light year (ly) is the distance light travels in one year, being about six million million miles.
  • The nearest star is over four ly away. The light from the sun takes about 8 minutes to reach earth.
  • Astronomers also use the par sec (pc), which is the distance of a star with a parallax of one arc second.
  • No star is as close as one par sec, but is close to that, being 1.3 pc. Stars are about 1 pc apart in our stellar neighborhood.
  • 1 pc = 3.26 ly.
Apparent Brightness of Stars
  • Apparent brightness is how bright a star appears to be, whether or not it is a nearby star, or extremely distant.
  • We still use the Greek system of apparent magnitudes.
  • The brightest stars were said to be first magnitude.
  • The dimmest stars visible in a dark sky far from a city are sixth magnitude.
  • The dimmest stars visible in a city are often only third magnitude.
  • There are fifteen first magnitude stars visible from the U.S. You should know their names and locations.
  • All of the stars in the Big Dipper are second magnitude stars.
  • The four stars in the bowl of the Little Dipper are of 2nd, 3rd, 4th, and 5th magnitude, so they are a good measuring stick for comparisons.
  • Modern astronomers define magnitudes so that a difference of five magnitudes is a factor of 100 in brightness. That means that some very bright stars have 0 magnitude, or even negative. Sirius has magnitude -1.
  • Venus has a magnitude of -4, the moon is about -12, and the sun is -26.

Measuring Properties of Stars

Absolute Magnitude
  • Absolute magnitude is defined to be what the apparent magnitude would be at a distance of 10 pc.
  • It measures the "absolute" brightness of a star, that is, how much light it is really emitting.
  • The absolute magnitude of the sun as about +5.
  • The absolute magnitude of Rigel is about -7, meaning it is really incredibly bright.
  • Many of the stars visible in the sky are the bright beacons. There are many closer stars too dim to see.
  • Absolute magnitude usually means the brightness at all wavelengths, also called absolute bolometric magnitude.
  • If one wants to refer only to wavelengths of visible light, then it is the absolute visual magnitude.
Spectra
  • A sprectrograph spreads the stars light into all of its component colors onto photographic film.
  • From stellar spectra, we can determine temperature, composition, pressures, rotational velocities, etc.
  • Most spectra have many absorption lines causes by cooler gases which absorb the light.
  • Stars are classified by their overall spectral characteristics.
  • The classes are O, B, A, F, G, K, M ("Oh, be a fine girl, kiss me.")
  • Those classes correspond to blue (O,B), white (A, F), yellow (G), orange (K) and red (M) stars.
Spectral Class Facts Worth Memorizing

Color
Spectral Class
Temperature (K)
Absorption Lines
Example Stars
Blue
O
30,000
Ionized Helium
Orion's Belt
Blue
B
18,000
Helium
Spica
Blue-White
A
10,000
Hydrogen (thick lines)
Sirius, Rigel
White
F
7,000
Hydrogen (thin lines)
Procyon
Yellow
G
5,500
Ionized Metals
Sun, Capella
Orange
K
4,000
Neutral Metals
Arcturus
Red
M
3,000
Molecules
Antares, Betelgeuse

The Doppler Shift
  • Light eminating from a source moving away from you is red-shifted, that is, the lines are moved toward red.
  • Light from a source moving toward you is blue-shifted.
  • The Doppler shift is used to measure a stars radial velocity, the velocity toward or away from us.
  • A star's rotation rate can be measured by broadening of spectral lines (half of star approaching, half receding).
Measuring Distances to Stars
  • Parallax (seeing nearby stars move relative to distant stars) can only be used for the nearest stars, within 100 pc.
  • Remember the parallax of even the very nearest star is less than one second of arc, which is extremely small.
  • There are other ways to calculate distances to more distant stars when other things are known, such as the luminosity.
Luminosity and the Stefan-Boltzman Law
  • The luminosity of a star is another unit to refer to the absolute magnitude of a star (at all wavelengths).
  • The unit is the luminosity of the sun. That is, the luminosity of the sun is 1.
  • The Stefan-Boltzman law is that the luminosity of every square meter of a star increases as the fourth power of the temperature.
  • That means that Luminosity is proportional to AT4, where A is the surface area, and T is the temperature.
  • For the nearest stars where the distance is known, one can calculate the luminosity because the apparent brightness decreases with the square of the distance.
  • There are other ways to determine the luminosity of certain stars, as will be discussed later.
Stellar Diameters
  • There are only a very few stars large enough to measure the diameters directly.
  • Most stars have their diameters calculated from their temperature and luminosity, using the Stefan-Boltzman law.
Stellar Masses
  • Masses for stars can be measured using binary stars (two stars in orbit around their center of mass).
  • The sum of the masses is known from the orbital period using Kepler's laws.
  • The ratio of the masses is known from measuring its distance from the center of mass.
  • From the ratio and sum of the masses, the mass of each can be calculated.
Stars with nearly identical spectra usually have nearly identical masses.

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