Stars - WhatisOutThere
Do the stars always appear in different places in the sky
Space - Stars
By Christine
Are the stars always in the sky?
What is a star?
A star is a ball of hot gas held together by its own gravity. The stars force of gravity is always causing the star to collapse. The gravity is a balance of hot gas and radiation coming from inside the star. This is called hydrostatic support. A star gives off light by nuclear burning in the stars core.
What is a star made of?
Stars are made of two very hot gases, hydrogen and helium. These are the two lightest elements. They shine by burning the hydrogen into helium in their cores, then later in life they create heavier elements.
Most stars have heavy elements, like carbon, nitrogen, oxygen and iron but only small amounts.
These elements came from the stars that existed before them. When a star runs out of fuel, it gives much of its elements back into space. New stars are made from this material, meaning that the material in stars is recycled.
Is the sun a star? How?
The sun is like any other star, it has an average size and temperature, and shines as bright as other stars do. Some stars are bigger and hotter and some a smaller and cooler. Like our sun there are billions of stars in our universe. We need the sun because it is our source of heat, light and energy, and without it we would not exist. If there was a small problem with the energy output of the sun, it could drastically affect our lives. The sun has a diameter of 1.4 million km across and an average surface temperature of 5800 Kelvin. At its equator, the sun turns once every 25 days.
Are the stars always in the sky?
– Day and night?
There are stars in the sky in the day and in the night. We can only see the stars in the night because they are shining so brightly in the night sky. Stars do glow during the day but we cannot see them because the light blue sky is so much brighter than the faint glow coming from the stars.
If you were standing on the moon for example, you would be able to see the stars both day and night.
This is because there is no atmosphere on the moon, meaning that it is always dark. Therefore you can see the stars.
Do the stars always appear in different places in the sky?
The stars move in two different ways. One is very obvious. The Earth rotates on its axis, which would make it look like the stars are moving once around the Earth every 24 hours. So it isn't the stars that are moving but the actual Earth itself. The other way, the stars are really moving through space relative to each other and Earth. But because the stars are so far away, this movement would require a telescope and precise measurements to be sure.
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Around how many stars are in the sky each night?
The number of stars in the sky still remains a mystery to this day, because there are just too many to count. Stars are not spread out everywhere in space but are grouped together in galaxies. Instead of counting the stars individually, scientists look at the size and brightness of each galaxy and estimate the number of stars that make it up. The milky way alone is made up of an estimate of 100,000,000,000 stars!! ( one hundred thousand million )! If someone tried to count the stars of the milky way, at a rate of one star per second, it would take over 3,170 years!!
How far away are the stars?
The stars are not all spread out evenly in our universe, meaning that they are not all the same distance from us. Some are closer and some are further away. If a star is glowing brightly it means it one of the closer stars. If a star is quite dim, it is much further away. Stars come in different brightness's and sizes. Larger stars shine more brightly than smaller stars do. The brightness of a star helps scientists estimate the size and how far away it is from us. The closest star is about
39,900,000,000,000 km away!!! ( thirty nine trillion,
900 billion ) but the furthest star is so much further away.
A stars temperature is determined by its colour
Characteristics?
Shapes of stars
The international research led by an Auckland astronomer has found stars are not just round twinkling dots in the night sky they can also be oval or shaped of a cigar. Dr Ian Bond from
Massey University says researchers have suspected for some time that stars come in various shapes and sizes, but there wasn't any obvious data as the stars are so far away.
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Bibliography/Picture Bibliography
Bibliography : http://imagine.gsfc.nasa.gov/docs/science/know_l2/stars.html
http://www.nmm.ac.uk/explore/astronomy-and-time/astronomyfacts/stars/what-is-a-star
http://coolcosmos.ipac.caltech.edu/cosmic_kids/AskKids/starcomp.s
html
http://starryskies.com/solar_system/sun/sun.html
http://answers.yahoo.com/question/index?qid=20080604222055AA hM8Vc
http://www.astronomywa.net.au/index.php?option=com_content&vi ew=article&id=312:how-many-stars-are-in-the-sky&catid=41:askan-astronomer&Itemid=12
http://coolcosmos.ipac.caltech.edu/cosmic_kids/AskKids/stardist.sht
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