Stars & Constellations D. Crowley, 2007

Stars & Constellations G To know what a star and constellation is Thursday, August 13, 2015

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)

Observable Constellations G Orion G Although stars are always drawn, or painted, in a light yellow or white shade, there are many which are coloured, even to the naked eye G This is true in the case of one of the best known of all the constellations, Orion - also known as the Hunter G Here, the top left star in Orion - the right shoulder - Betelgeuse - is a giant red star. In comparison, the bottom right star of the constellation, Orion's right foot - Rigel - is blue G There are three stars that represent Orion's "belt", and three below which make up his "sword". Of those that are the sword, one is not a star but a nebula, where stars are formed G Orion G Although stars are always drawn, or painted, in a light yellow or white shade, there are many which are coloured, even to the naked eye G This is true in the case of one of the best known of all the constellations, Orion - also known as the Hunter G Here, the top left star in Orion - the right shoulder - Betelgeuse - is a giant red star. In comparison, the bottom right star of the constellation, Orion's right foot - Rigel - is blue G There are three stars that represent Orion's "belt", and three below which make up his "sword". Of those that are the sword, one is not a star but a nebula, where stars are formed

Observable Constellations G Ursa Major G Ursa Major - also known as the Plough - can be seen in the UK all year round G It is identifiable by the double star that represents the handle of the plough, which some people know as the horse and rider G With the naked eye, it's clear that there are two stars here, but if you turn binoculars or a telescope on this constellation, it becomes clear that there are three G Ursa Major G Ursa Major - also known as the Plough - can be seen in the UK all year round G It is identifiable by the double star that represents the handle of the plough, which some people know as the horse and rider G With the naked eye, it's clear that there are two stars here, but if you turn binoculars or a telescope on this constellation, it becomes clear that there are three

Observable Constellations G Andromeda Galaxy G The Andromeda Galaxy is about the most distant object - at 2.5 million light-years away - that it is possible for anyone to see in the night sky G Much of the lure of this galaxy is its impressive distance from us, that the time the light took to reach us began so many years before man even inhabited the Earth. Astronomy really is a time machine - you are seeing all the stars in a different time, depending how long it's taken the light from them to get to us G As the seasons change, so do the stars which are most visible - the best time to view the Andromeda Galaxy is in the autumn G Andromeda Galaxy G The Andromeda Galaxy is about the most distant object - at 2.5 million light-years away - that it is possible for anyone to see in the night sky G Much of the lure of this galaxy is its impressive distance from us, that the time the light took to reach us began so many years before man even inhabited the Earth. Astronomy really is a time machine - you are seeing all the stars in a different time, depending how long it's taken the light from them to get to us G As the seasons change, so do the stars which are most visible - the best time to view the Andromeda Galaxy is in the autumn

Observable Constellations G Pleiades G Seven stars which are clearly identifiable are called Pleiades, also known as Seven Sisters, and individually named after the sisters in Greek mythology: Sterope, Merope, Electra, Maia, Taygete, Celaeno, and Alcyone G these are relatively young stars, only a couple of million years old, and are a brilliant blue colour G These stars are most clearly visible in the Northern Hemisphere from late summer into autumn G Pleiades G Seven stars which are clearly identifiable are called Pleiades, also known as Seven Sisters, and individually named after the sisters in Greek mythology: Sterope, Merope, Electra, Maia, Taygete, Celaeno, and Alcyone G these are relatively young stars, only a couple of million years old, and are a brilliant blue colour G These stars are most clearly visible in the Northern Hemisphere from late summer into autumn

Observable Constellations G The Milky Way G The galaxy that is the Milky Way - the galaxy the Earth is part of - is another well-known feature of the night sky G It arches right overhead us, across the sky - it is a band of cloud with structure, and it is one sky feature that it is possible to see anywhere but in the most central part of cities. G The Milky Way G The galaxy that is the Milky Way - the galaxy the Earth is part of - is another well-known feature of the night sky G It arches right overhead us, across the sky - it is a band of cloud with structure, and it is one sky feature that it is possible to see anywhere but in the most central part of cities.