Stars
How far away is a star?
Students can be shown how the brightness of a light, like the light from a star, can change as the distance from the light changes. You would need a darkened room, a white board or blank wall, and two flashlights (one with a bigger light than the other). With the lights in the room off or dimmed, have one student turn on the smaller flashlight and hold it one yard from the board. Then have the student step back so he/she is two yards away from the board. Have students discuss what they see. They should notice that the light on the wall becomes more spread out and dimmer (in fact, it will be one fourth as bright as is was initially. Have the student step back again so now he/she is three yards away and have the class compare the results. Now the light should be dimmer still (one ninth as bright as the first). If this light came from a star, students should realize that the further away the star is, the dimmer it is. Ask the students if the light bulb in the flashlight is changing (they should say no). Students should realize that the light from a star is always producing the same amount of light at all times, but the distance from the observer to the star makes the light appear to be dimmer.
Students can be shown how the brightness of a light, like the light from a star, can change as the distance from the light changes. You would need a darkened room, a white board or blank wall, and two flashlights (one with a bigger light than the other). With the lights in the room off or dimmed, have one student turn on the smaller flashlight and hold it one yard from the board. Then have the student step back so he/she is two yards away from the board. Have students discuss what they see. They should notice that the light on the wall becomes more spread out and dimmer (in fact, it will be one fourth as bright as is was initially. Have the student step back again so now he/she is three yards away and have the class compare the results. Now the light should be dimmer still (one ninth as bright as the first). If this light came from a star, students should realize that the further away the star is, the dimmer it is. Ask the students if the light bulb in the flashlight is changing (they should say no). Students should realize that the light from a star is always producing the same amount of light at all times, but the distance from the observer to the star makes the light appear to be dimmer.
http://www.yorku.ca/ns1745b/fig9-light-distance.jpg
Now have a second student use the larger light at the same time as the small one. Repeat the process with both lights at the same time so students can compare how the brightness between the small and large light differ. They should see that the larger light is brighter than the small one when they are at the same distance from the wall. As both lights move further away, they both will get progressively dimmer.
What is a star made of?
The atoms that make up a star can be identified by looking at the spectrum of light it emits. Students can be shown what the light spectrum of certain elements look like using spectral glasses and the special light bulbs with specific elements inside. Once students realize that each element has a unique light spectrum, they can use this knowledge to identify what elements make up a star.
Students can use a special website to test their ability to identify elements with a given spectrum:
http://jersey.uoregon.edu/elements/Elements.html (be sure to click on Emissions)
You look at the night sky and using your knowledge of spectrology, you see the following spectrums when viewing stars. Use the link above to help you identify what element the star is made of. Scroll to the bottom of the pages for the answers.
The atoms that make up a star can be identified by looking at the spectrum of light it emits. Students can be shown what the light spectrum of certain elements look like using spectral glasses and the special light bulbs with specific elements inside. Once students realize that each element has a unique light spectrum, they can use this knowledge to identify what elements make up a star.
Students can use a special website to test their ability to identify elements with a given spectrum:
http://jersey.uoregon.edu/elements/Elements.html (be sure to click on Emissions)
You look at the night sky and using your knowledge of spectrology, you see the following spectrums when viewing stars. Use the link above to help you identify what element the star is made of. Scroll to the bottom of the pages for the answers.
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3.This star is made of what element?
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How hot is a star?
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The color of a star can help observers to estimate the temperature of a star. Very hot stars are blue in color. As they get cooler, they change from blue to white to yellow to orange and then red. Stellarium is great for seeing the color of stars without having to go outside in the middle of a cloudless night. The two pictures below were taken from Stellarium and show the color of some common stars such as the sun, Spica, Antaires, Bellatrix, and Sirius.
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The Sun
Spica
Altair
Proxima
Pollux
Sirius
Polaris
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The closest star to Earth is the Sun. The temperature of the sun is 5,800 Kelvin and it is a yellow-white color. Can you match the star temperature with the star name? Hint: remember the color order from hottest to coolest. Scroll to the bottom of the page for answers.
22,000 Kelvin: _________________ 9,500 Kelvin: __________________ 8,700 Kelvin: __________________ 7,400 Kelvin: __________________ 5,100 Kelvin: __________________ 4,370 Kelvin: __________________ |
The life cycle of Stewart the Star
As a nebula cloud of cosmic matter swirled around in space, gravity began to pull all of the material together, tighter and tighter, spinning faster and faster! As the object grew hotter and hotter, some the matter called Hydrogen began to change into something different: Helium! As this change occurred, this object in space began to glow, and Stewart the star was born.
Stewart was just like any other protostar. His insides constantly changed Hydrogen into Helium, making him glow warmly. It gave him great joy to brighten space and as he grew older he also grew hotter. He was now almost ten thousand degrees Fahrenheit! He was now about the same size of a star you might know: the sun! Stewart was proud to say that he was now a main sequence star.
Stewart glowed with his other star friends, each one a different size or color. His nearby friend, Georgette, was a giant star! She was three times as large as him! Together they gave light and warmth to the space around them.
As time went on, Stewart knew the Hydrogen in his inside was almost all changed into Helium. It was time for the next exciting change. As the last Hydrogen atom was changed, he began to cool down. His inside shrunk, but his outside layers expanded! He grew larger! And his color was changing! He was now a red giant.
Now the helium inside of Stewart was changing into a different thing: Carbon. His insides shrunk again and his outside layers shot out all around him! A planetary nebula shooting out into space. The inside of Stewart that was still left was now a white dwarf.
Stewart's friend Georgette was also changing. But she was so much bigger than him, her change was different. Her insides kept changing and changing until her inside was turned into Iron and she became a red supergiant! That was when there was a giant blast and Georgette's outer layers exploded out into a supernova! Stewart thought it was so cool to see. Then Georgette changed into a neutron star. If she had been any bigger, she might have become a black hole!
Stewart spent the last of his days changing from a white dwarf to a black dwarf, billions of years old. He had a long and happy life and he saw all of space.
(information from: http://imagine.gsfc.nasa.gov/docs/teachers/lessons/xray_spectra/background-lifecycles.html)
As a nebula cloud of cosmic matter swirled around in space, gravity began to pull all of the material together, tighter and tighter, spinning faster and faster! As the object grew hotter and hotter, some the matter called Hydrogen began to change into something different: Helium! As this change occurred, this object in space began to glow, and Stewart the star was born.
Stewart was just like any other protostar. His insides constantly changed Hydrogen into Helium, making him glow warmly. It gave him great joy to brighten space and as he grew older he also grew hotter. He was now almost ten thousand degrees Fahrenheit! He was now about the same size of a star you might know: the sun! Stewart was proud to say that he was now a main sequence star.
Stewart glowed with his other star friends, each one a different size or color. His nearby friend, Georgette, was a giant star! She was three times as large as him! Together they gave light and warmth to the space around them.
As time went on, Stewart knew the Hydrogen in his inside was almost all changed into Helium. It was time for the next exciting change. As the last Hydrogen atom was changed, he began to cool down. His inside shrunk, but his outside layers expanded! He grew larger! And his color was changing! He was now a red giant.
Now the helium inside of Stewart was changing into a different thing: Carbon. His insides shrunk again and his outside layers shot out all around him! A planetary nebula shooting out into space. The inside of Stewart that was still left was now a white dwarf.
Stewart's friend Georgette was also changing. But she was so much bigger than him, her change was different. Her insides kept changing and changing until her inside was turned into Iron and she became a red supergiant! That was when there was a giant blast and Georgette's outer layers exploded out into a supernova! Stewart thought it was so cool to see. Then Georgette changed into a neutron star. If she had been any bigger, she might have become a black hole!
Stewart spent the last of his days changing from a white dwarf to a black dwarf, billions of years old. He had a long and happy life and he saw all of space.
(information from: http://imagine.gsfc.nasa.gov/docs/teachers/lessons/xray_spectra/background-lifecycles.html)
http://www.enchantedlearning.com/subjects/astronomy/stars/lifecycle/
What fuels a star like our sun?
Nuclear Fusion
Nuclear Fusion
(Above) First, two separate hydrogens react together. After the reaction, a positron and a neutrino come out of the reaction leaving the two hydrogens formed together. Then those stuck hydgrogens react with a single hydrogen. After the reaction a photon leaves and a 3Helium is formed.
(Above) Second, this same reaction occurs again, so now there is two 3Heliums left from these two separate reactions.
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(Above) Last, these two 3Heliums meet up and react together. After the reaction, two lonely hydrogens come out of the reaction and go there separate ways and a 4Helium is produced.
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Nuclear fusion fuels stars. In our sun, Hydrogen atoms combine in a series of reactions (see above) to form Helium. For more information on the chemical process and reactions, click here.
The above video explains the history of the universe. It tells of the theory of the Big Bang. It explains how everything we know of started in one small point in space that expanded out to form what we know today. It tells of our galaxies among the 125 billion galaxies in the universe. It explains how the universe is grown bigger through expansion and explains how by reversing the expansion through time we can tell how everything that exists had once started all clumped together in one small atom. The first 8 minutes explains what the big bang is. After that, it tells of how humans came to this theory and what led up to this thought through history. The first humans would explain the things they saw in the sky with stories of the gods. (11:00) and how the sights seen in the sky would tell of fate (13:00). It tells of the first conclusions that were incorrect (15:00). Ancient Greeks (16:00) , Ptolemy (17:00), Heliocentrism and Copernicus (20:00), Galileo, Newton, Einstein, an infinite universe (38:00), the explanation of gravity (42:00), an expanding universe (46:00), to the big bang theory (47:00), Hubble and the expanse of the universe (52:00), Alternative theory the Steady State universe (55:00), evidence supporting the Big Bang (1:00:00), the way to measure the aftershock radiation of the Big Bang (1:05:00), the creation of the elements (1:11:00), problems with the Big Bang (1:12:00), picture of universe when it was a "baby" (1:28:00), full timeline of big bang (1:18:00), and what's to come (1:25:00)
Answers:
What is a star made of?
1. Carbon
2. Hydrogen
3. Helium
How hot is a star?
Spica: 22,000 K
Sirius: 9,500 K
Altair: 8,700 K
Polaris: 7,400 K
Pollux: 5,100 K
Proxima: 4,370 Khttp://www.essex1.com/people/speer/main.html
What is a star made of?
1. Carbon
2. Hydrogen
3. Helium
How hot is a star?
Spica: 22,000 K
Sirius: 9,500 K
Altair: 8,700 K
Polaris: 7,400 K
Pollux: 5,100 K
Proxima: 4,370 Khttp://www.essex1.com/people/speer/main.html
