Stars & ConstellationsStars & Constellations

D. Crowley, 2007D. Crowley, 2007

Stars & ConstellationsStars & Constellations

To know what a star and constellation is To know what a star and constellation is

Wednesday, April 19, 2023

How big is the universe?How big is the universe?

Cut out the pictures, order them, and stick them into your book…

Cut out the pictures, order them, and stick them into your book…

Person School Town Country

Planet Solar system Galaxy GalaxiesUNIVERSE

SizesSizes

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StarsStars What is a star? What is the sun?

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

Stars emit light and radiation (unlike planets) due to this nuclear reaction - they are the sources of light!

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!

What is a star? What is the sun?

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

Stars emit light and radiation (unlike planets) due to this nuclear reaction - they are the sources of light!

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!

StarsStars Why is our star (the sun) so big? How far away are other

stars?

Our sun looks much bigger than all the other stars we can see, but actually its quite ordinary (not the biggest, not the smallest)

Our sun is one of many millions of stars which forms the galaxy The Milky Way

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!

Why is our star (the sun) so big? How far away are other stars?

Our sun looks much bigger than all the other stars we can see, but actually its quite ordinary (not the biggest, not the smallest)

Our sun is one of many millions of stars which forms the galaxy The Milky Way

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 MovementStar Movement

Why do the stars move across the sky?

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.

Why do the stars move across the sky?

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?How many stars?

How many stars are there?!

This is a tough question to answer, as there seem to be lots to count

We estimate there are thousands or millions of stars in our galaxy, the Milky Way

And don’t forget there are billions of other galaxies…

That makes for a lot of stars!

How many stars are there?!

This is a tough question to answer, as there seem to be lots to count

We estimate there are thousands or millions of stars in our galaxy, the Milky Way

And don’t forget there are billions of other galaxies…

That makes for a lot of stars!

ConstellationsConstellations

What are constellations? Can you name any?

Constellations are groups of stars which may resemble something. We make up constellations, so it makes it easier for us to spot individual stars

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

What are constellations? Can you name any?

Constellations are groups of stars which may resemble something. We make up constellations, so it makes it easier for us to spot individual stars

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

ConstellationsConstellationsE.g. the Big Dipper;

Orion; Cassiopeia etc…

Using ConstellationsUsing Constellations How do you think constellations can be useful?

Many would have used the constellations for religious purposes - i.e. they may have formed a shape which early people took to mean something

Agriculture has also benefited from constellations - some constellations are only seen during certain parts of the year - this helped before proper calendar systems!

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

How do you think constellations can be useful?

Many would have used the constellations for religious purposes - i.e. they may have formed a shape which early people took to mean something

Agriculture has also benefited from constellations - some constellations are only seen during certain parts of the year - this helped before proper calendar systems!

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 skyReading the night sky Have a go at the worksheet, reading the night sky…

Constellations move in the night sky because the Earth is rotating

We see different constellations at different times of the year because the Earth orbits around the sun

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)

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)

Have a go at the worksheet, reading the night sky…

Constellations move in the night sky because the Earth is rotating

We see different constellations at different times of the year because the Earth orbits around the sun

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)

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 ConstellationsObservable Constellations Orion

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

This is true in the case of one of the best known of all the constellations, Orion - also known as the Hunter

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

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

Orion

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

This is true in the case of one of the best known of all the constellations, Orion - also known as the Hunter

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

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 ConstellationsObservable Constellations Ursa Major

Ursa Major - also known as the Plough - can be seen in the UK all year round

It is identifiable by the double star that represents the handle of the plough, which some people know as the horse and rider

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

Ursa Major

Ursa Major - also known as the Plough - can be seen in the UK all year round

It is identifiable by the double star that represents the handle of the plough, which some people know as the horse and rider

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 ConstellationsObservable Constellations Andromeda Galaxy

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

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

As the seasons change, so do the stars which are most visible - the best time to view the Andromeda Galaxy is in the autumn

Andromeda Galaxy

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

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

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 ConstellationsObservable Constellations Pleiades

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

these are relatively young stars, only a couple of million years old, and are a brilliant blue colour

These stars are most clearly visible in the Northern Hemisphere from late summer into autumn

Pleiades

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

these are relatively young stars, only a couple of million years old, and are a brilliant blue colour

These stars are most clearly visible in the Northern Hemisphere from late summer into autumn

Observable ConstellationsObservable Constellations The Milky Way

The galaxy that is the Milky Way - the galaxy the Earth is part of - is another well-known feature of the night sky

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.

The Milky Way

The galaxy that is the Milky Way - the galaxy the Earth is part of - is another well-known feature of the night sky

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.