Unit 1: Space 1

Section 10-1 Notes 2

Celestial Bodies Celestial bodies are natural objects out in space including planets, stars, moons, asteroids and comets. 3

Celestial Bodies People have used celestial bodies to track the time of year. Certain celestial bodies can be viewed (or not viewed!) in specific locations in winter, spring, summer and autumn. 4

Celestial bodies have also been a source of fear in times when we did not understand what was happening. Comets, meteors and eclipses could seem quite disturbing when not understood. 5

Constellations and Asterisms Since ancient times people have observed what appear to be patterns in the stars which we call constellations. 6

Constellations and Asterisms Different cultures came up with different stories about these constellations. Many of them were about gods, kings and queens, mythological beasts, animals and heroes. 7

Asterisms are smaller groups of stars contained within constellations. The big dipper is an asterism found within the Ursa Major constellation! 8

Constellations and Asterisms Example: Orion’s belt in the image to the right is an example of an asterism. The Big dipper and the little dipper are also asterisms, not constellations! 9

Constellations You Need to know: Several Constellations that you need to know about include – Ursa Major, – Ursa Minor – Orion. 10

Ursa Major (The Big Bear) Can be viewed from the northern hemisphere when looking north. Contains the familiar asterism called “The Big Dipper” Can help you find the North star (called Polaris) 11

Ursa Minor (The Little Bear) Can only be viewed from the northern hemisphere. Contains the guiding star known as the North Star (Polaris) 12

Orion (The Hunter) Can be seen in Newfoundland from later fall until early spring. The three stars in the middle are known as Orion’s Belt, an easily observed asterism. 13

Interesting Fact: – Orion’s Belt points to the brightest star in the sky known as Sirius. 14

MOTION OF CELESTIAL BODIES 15

The movement of the stars tells us that the earth rotates on an axis, and that the Northern end of the axis currently points toward Polaris (the north star). 16

Movement of Stars 17

Movement of the Stars As the earth rotates, the stars appear to rotate about a central point. That apparent motion is because we are moving! The stars are too far away to move that quickly across the sky. 18

Movement of The Earth (and other planets) Planets like earth move in two ways: 1) Revolutions ( also called orbits) 2) Rotations (spinning) 19

Revolutions The path of earth and other planets as they revolve around the sun are known as orbits. (Draw) Orbit 20

Movement of the Planets Gravity from the sun is what keeps planets in orbit. The speed of planet movement keeps them from falling into the sun. (Draw) 21

Our ability to see certain constellations at certain times of the year is a result of the earth’s revolution around the sun. Earth takes days to revolve around the sun. This is one year 22

Motion of Planets Ancient Greeks noticed “wandering stars” and realized they were different from the background stars. They called them planets. Mars: Retrograde MotionRetrograde Motion 23

Motion of Planets (not in notes) The other planets in our solar system also move in orbits. Some are larger than earth’s, others are smaller. 24

Motion of Planets Those planets inside Earth’s orbit (Mercury and Venus) appear to race through the sky and appear to be close to the Sun (we explore the planets in more detail later!) 25

2) Rotations Stars, planets, and moons all rotate (spin) about a central axis. The earth rotates on its axis once every 24 hours. Once a day! 26

Movement of the Sun As the earth rotates, the sun follows a daily path through the sky known as the ecliptic This changes based on the season: – Highest during summer – Lowest during winter Video: (watch to 3:40) 27

Motion of Asteroids and Comets Asteroids are small rocky bodies in our solar system. Although small is a relative term. 28

Motion of Asteroids and Comets Comets are chunks of frozen gases and cosmic dust. 29

Motion of Asteroids and Comets Asteroids and Comets orbit around the sun Most asteroids in our solar system orbit the Sun between Mars and Jupiter. 30

Motion of the Moon The moon orbits around Earth once every 28 days. It also rotates once every 28 days, so we always see the same side of the moon! 31

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