Stars & Constellations D. Crowley, 2007

Stars & Constellations G To know what a star and constellation is

How big is the universe? G Cut out the pictures, order them, and stick them into your book… PersonSchoolTownCountry PlanetSolar systemGalaxyGalaxies UNIVERSE

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Stars G What is a star? What is the sun? G Stars form from clouds of dust, which spiral together due to gravitational attraction. The gravity compresses the matter so much that intense heat develops, causing a nuclear fusion reaction G Stars emit light and radiation (unlike planets) due to this nuclear reaction - they are the sources of light! G But remember - the sun is a star too! It just looks different to all the other twinkles in the sky, because it is so much closer to us than any other star! G What is a star? What is the sun? G Stars form from clouds of dust, which spiral together due to gravitational attraction. The gravity compresses the matter so much that intense heat develops, causing a nuclear fusion reaction G Stars emit light and radiation (unlike planets) due to this nuclear reaction - they are the sources of light! G But remember - the sun is a star too! It just looks different to all the other twinkles in the sky, because it is so much closer to us than any other star!

Stars G Why is our star (the sun) so big? How far away are other stars? G Our sun looks much bigger than all the other stars we can see, but actually its quite ordinary (not the biggest, not the smallest) G Our sun is one of many millions of stars which forms the galaxy The Milky Way G The distance between stars is usually millions of times greater than the distance between planets in our solar system - but remember, these planets are millions of kilometers apart themselves! G Why is our star (the sun) so big? How far away are other stars? G Our sun looks much bigger than all the other stars we can see, but actually its quite ordinary (not the biggest, not the smallest) G Our sun is one of many millions of stars which forms the galaxy The Milky Way G The distance between stars is usually millions of times greater than the distance between planets in our solar system - but remember, these planets are millions of kilometers apart themselves!

Star Movement G Why do the stars move across the sky? G The stars seem to move across the sky because the Earth is rotating. Just like we see the sun rise and set, the stars seem to move across the sky as the Earth spins. G Why do the stars move across the sky? G The stars seem to move across the sky because the Earth is rotating. Just like we see the sun rise and set, the stars seem to move across the sky as the Earth spins.

How many stars? G How many stars are there?! G This is a tough question to answer, as there seem to be lots to count G We estimate there are thousands or millions of stars in our galaxy, the Milky Way G And don’t forget there are billions of other galaxies… G That makes for a lot of stars! G How many stars are there?! G This is a tough question to answer, as there seem to be lots to count G We estimate there are thousands or millions of stars in our galaxy, the Milky Way G And don’t forget there are billions of other galaxies… G That makes for a lot of stars!

Constellations G What are constellations? Can you name any? G Constellations are groups of stars which may resemble something. We make up constellations, so it makes it easier for us to spot individual stars G It helps as it breaks the night sky up into manageable bits, so you may be able to identify a group of stars very quickly and easily, e.g. The Big Dipper G What are constellations? Can you name any? G Constellations are groups of stars which may resemble something. We make up constellations, so it makes it easier for us to spot individual stars G It helps as it breaks the night sky up into manageable bits, so you may be able to identify a group of stars very quickly and easily, e.g. The Big Dipper

Constellations E.g. the Big Dipper; Orion; Cassiopeia etc…

Using Constellations G How do you think constellations can be useful? G Many would have used the constellations for religious purposes - i.e. they may have formed a shape which early people took to mean something G Agriculture has also benefited from constellations - some constellations are only seen during certain parts of the year - this helped before proper calendar systems! G Navigation also used constellations, and sometimes still does today. Some constellations could be spotted, e.g. Ursa Minor contain Polaris, the North Star (which always points North). Once navigators had found North, they could observe its height in the sky and hence work out their latitude (how far North / South they are). Now they know how far North they are + the direction they’re traveling G How do you think constellations can be useful? G Many would have used the constellations for religious purposes - i.e. they may have formed a shape which early people took to mean something G Agriculture has also benefited from constellations - some constellations are only seen during certain parts of the year - this helped before proper calendar systems! G Navigation also used constellations, and sometimes still does today. Some constellations could be spotted, e.g. Ursa Minor contain Polaris, the North Star (which always points North). Once navigators had found North, they could observe its height in the sky and hence work out their latitude (how far North / South they are). Now they know how far North they are + the direction they’re traveling

Reading the night sky G Have a go at the worksheet, reading the night sky… G Constellations move in the night sky because the Earth is rotating G We see different constellations at different times of the year because the Earth orbits around the sun G However some constellations can be seen all year round. Some, like Cassiopeia are circumpolar - this means they circle above the pole, so can always been seen (the Earth’s orbit around the sun does not affect their viewing) G Navigation utilises constellations - it helps locate a specific star, such as Polaris (the North Star). Knowing this, plus how high the star is in the sky gives a navigator their direction + their latitude (how far North / South they are) G Have a go at the worksheet, reading the night sky… G Constellations move in the night sky because the Earth is rotating G We see different constellations at different times of the year because the Earth orbits around the sun G However some constellations can be seen all year round. Some, like Cassiopeia are circumpolar - this means they circle above the pole, so can always been seen (the Earth’s orbit around the sun does not affect their viewing) G Navigation utilises constellations - it helps locate a specific star, such as Polaris (the North Star). Knowing this, plus how high the star is in the sky gives a navigator their direction + their latitude (how far North / South they are)