The Sun and Other Stars &Rotation and Revolution

Unit 8Lessons 1 & 2

VOCABULARY1. Star – an object in space that produces its

own energy, including heat and light

2. Astronomical unit – the mean, or average, distance between the Sun and Earth

3. Solar flares – occasional eruptions of energy from the Sun’s surface

4. Constellation – any of the patterns that are formed by a group of stars in the night sky

5. Solar system – a star and the objects that orbit it

6. Aurora borealis – also know as the northern lights; energy from solar flares causes a display of different colored lights in the Earth’s atmosphere

7. Solar wind – a fast moving stream of particle thrown into space by solar flares

8. Polaris – the North Star; it will always be directly north of your location

9. Magnitude – the brightness of a star

10. Absolute magnitude – a star’s actual brightness

11. Apparent magnitude – how bright a star looks in Earth’s night sky

12.Gravity – the force of attraction between any two objects due to their mass

13. Orbit – the path one object takes as it travels around another object

14. Inertia – the tendency of a moving object to keep moving and an object at rest to stay at rest

15. Rotation – a complete spin on an axis; the spinning of Earth on its axis

16. Revolution – one complete trip on a closed path of one object around another object; this is the movement that Earth does around the sun

17. Universe – everything that exists – planets, stars, dust, gases, and energy

18. Galaxy – a group of stars, gas, and dust

19. Light year – the distance light travels in one Earth year; 9.5 trillion km

20. What are the layers of the Sun?

• Radiation layer– next to the core– Moves the energy produced in the core in every

direction– It can take millions of years for energy to move out

of this layer

• Core

– Most of the energy that the Sun produces is formed in its core

– At its core, the Sun has a temperature of 10 million to 20 million degrees Celsius (18 million to 36 million degrees Fahrenheit)

• Convection layer

– Gases with different energies move in circles in a way similar to air with different densities

– Energy moves out of this layer in about a week

• Photosphere

– the visible surface of the Sun

– It is not a solid surface, but a layer of gases

– It is cooler that the core

• Chromosphere

– The second layer

– It is the inner layer of the Sun’s atmosphere

– When it can be seen, it looks like a red circle around the Sun

• Corona

– The outermost layer of the Sun’s atmosphere

– It takes on different shapes around the Sun depending on changes in the temperature of the photosphere

21. Facts about the Sun

• The Sun is an average sized and temperature star

• The largest object in the solar system• The Sun’s diameter is about 1,390,000 km or

863,706 miles• The Sun is a huge sphere made up mostly of

two very light gases, hydrogen and helium

• Solar Energy, the energy generated by the sun. This energy is in the form of electromagnetic radiation and travels to the earth in waves of various lengths.

• The Earth makes this trip in one year, or in 365 ¼ days

• The Sun produces two types of energy– Thermal energy, Light energy

• The mass of the Sun makes up 99.8 percent of all the mass in the solar system.

22. Why does the Sun appear much larger than other stars?

• The Sun looks larger because it is much closer to Earth

23. Why are the planets not stars?

• Planets do not produce their own light

24. Where in the Sun is energy produced?

• In the core

25. Why is it harmful to our eyes to look directly at the Sun?

• The Sun emits powerful energy in the form of radiation, which can be damaging to our eyes

26. Why did ancient cultures group stars into constellations?

• Constellations can help provide a point of reference

27. How were constellations used in the past?

• If Polaris can be found or some other recognizable star whose direction was known, they would follow that star while you travel

28. Why do astronomers today still use constellation?

• They give us reference points for finding objects in the night sky

29. What two constellations point to Polaris?

• The Big dipper and the Little Dipper point to Polaris, the North Star

30. What does a star’s color tell you?

• A star’s color tells you about its surface temperature.

• Red and orange colors indicate cooler stars

• Yellow indicates hotter stars

• Blue white indicates the hottest stars

31. Why do some stars appear brighter than another?

• Stars appear less bright the farther they are from Earth

32. What does the strength of the pull of gravity depend on?

• The strength of the pull of gravity is affected by the total mass of the two objects and by the distances between them.

• The pull of gravity decreases when the total mass of the two objects decreases and when the objects are farther apart

33. Why does an astronaut weigh less on the moon than on Earth?

• The Moon has less mass than Earth and therefore the pull of gravity is not as strong.

34. In what direction would the planets travel if the Sun suddenly disappeared?

• Without the Sun’s gravity pulling the planets inward, the planets would fly off into space in a straight line from their position in their orbit.

35. What two things make Earth follow its path?

• As Earth orbits the Sun, it is pulled toward the Sun because of gravity.

• At the same time, Earth’s inertia makes it move away from the Sun.

36. What is the type of path does the Earth take?

• As a result of the effects of gravity and inertia, Earth moves in a nearly circular orbit called and ellipse.

37. Which movement causes day and night?

• Earth’s rotation on its axis

38. In which direction does Earth rotate?

• Earth rotates from west to east

39. Why does the Sun appear to rise in the east and set in the west?

• As Earth rotates from west to east, objects in the sky such as the Sun, Moon and stars all appear to move in the direction opposite Earth’s movement

40. What is standard time zone?

• A standard time zone is a vertical belt, about 15 degrees wide in longitude, in which all locations have the same time.

41. How many time zones are there in the U.S.?

• The U.S. states have 6 time zones.

42. List the 6 time zones

• Alaska Standard Time (AST)• Hawaii-Aleutian Standard Time (HAST)• Pacific Standard Time (PST)• Mountain Standard Time (MST)• Central Standard Time (CST)• Eastern Standard Time (EST)

43. What would happen if you traveled west across the International Date Line?

• West of the International Date Line it is 1 calendar day later than it is in places east of the line

44. Why do the constellations seem to move across the night sky?

• The constellations appear to move across the sky because Earth is rotating on its axis

45. Why do many of the constellations seem to change from season to season?

• As Earth revolves around the Sun, different constellations become visible on the night side of Earth while others become hidden in the glare of the Sun

46. What causes Earth’s seasons to change?

• As Earth revolves around the Sun, sunlight strikes different parts of Earth at different angles.

47. Which star can help you find your way when you are lost?

• Polaris, the North Star

48. How did ancient cultures use constellations?

• Constellations were used as seasonal calendars and for navigation.

49. A pattern of stars in the night sky is called a….

• Constellation.