How Do Stars Work? | Learn About Stars, Gravity & Nuclear Fusion | Science for Kids — Transcript

Full transcript

1. 0:00Hey Brainiacs
2. 0:02Outer space is so cool!
3. 0:06Lizzy and I love to get away from the bright city
4. 0:08lights to look up at the stars at night.
5. 0:13It’s fun to imagine what it would be like to explore
6. 0:17the universe in our very own spaceship and see other
7. 0:20planets, nebulas, and stars up close!
8. 0:28Welcome back to Brain Candy TV.
9. 0:35Well, today is our lucky day!
10. 0:39We’ve added hyperjets to our Weather Explorer truck
11. 0:42and we’ll be hitching a ride on this huge rocket that
12. 0:46can help us get all the way into deep space.
13. 0:50The rocket needs to be this big because it is filled
14. 0:54with a whole bunch of rocket fuel so that it has
15. 0:57enough energy to escape Earth’s gravity.
16. 1:03Gravity is what makes everything fall to the ground,
17. 1:07like when you throw a ball up into the air.
18. 1:11It’s also what keeps the moons, planets, and stars
19. 1:16moving in their orbits.
20. 1:18All massive objects have gravity, and the more massive
21. 1:22the object, the stronger the gravity.
22. 1:26But gravity is mostly noticeable around really heavy
23. 1:30objects like stars, planets, and moons.
24. 1:38Since the moon is much smaller and less massive than the Earth,
25. 1:43the moon’s gravity is weaker, so if you were standing
26. 1:47on the moon, you could throw a ball around six times
27. 1:50higher than you could on Earth.
28. 1:54And if we drove our space explorer truck on the moon,
29. 1:58it could do some amazing jumps, since the moon’s
30. 2:01gravity is six times weaker than on Earth.
31. 2:05Whoa, look how far that heavy truck can jump on
32. 2:10the moon!
33. 2:12Let’s learn more about gravity and how it works.
34. 2:18A very smart scientist named Albert Einstein
35. 2:23discovered that massive objects like stars and planets
36. 2:27will curve the space and even the time around them.
37. 2:31They sort of make a dent in spacetime which makes
38. 2:35other things fall toward them.
39. 2:38It’s sort of like if you place a heavy bowling ball
40. 2:41on a trampoline.
41. 2:43The heavy ball curves the fabric of the trampoline
42. 2:47like a planet will curve the fabric of spacetime.
43. 2:51If you place some lighter balls on the curved fabric,
44. 2:54they will get pulled toward the heavy object in
45. 2:57the centre.
46. 2:58And if you send them rolling around the edge, they
47. 3:01will orbit the centre, almost like how the moon
48. 3:04orbits the Earth.
49. 3:07Gravity is an important part of how stars and planets
50. 3:10move, but it’s also a key ingredient for how a star
51. 3:14is made.
52. 3:17OK, let’s get ready for our rocket ride into space!
53. 3:22We’re going to visit a place called a nebula, where
54. 3:26we can learn all about how stars are made and how
55. 3:29they work!
56. 3:32Lizzy is all ready go and she’s excited to learn
57. 3:35more about stars.
58. 3:37Let’s start the countdown!
59. 3:4110, 9, 8, 7, 6, 5, 4, 3, 2, 1...Fire!
60. 3:54Woohoo, we have liftoff!
61. 3:58Hang on tight Lizzy, this could get a bit bumpy!
62. 4:03Gravity is working hard to pull the heavy rocket
63. 4:06back down toward the centre of the Earth, but the
64. 4:09powerful thrust from the rocket engines is strong
65. 4:12enough to overcome Earth’s gravity.
66. 4:18Awesome, we made it all the way up into outer space!
67. 4:23Our planet Earth looks so beautiful from up here!
68. 4:28OK, Lizzy, time to activate the hyperjets and
69. 4:32explore the galaxy!
70. 4:51Whoa, look at THAT!
71. 4:54This area of space is called a nebula.
72. 4:58A nebula is a huge cloud of dust and gas.
73. 5:03They are mostly made of the lightest and simplest
74. 5:06forms of matter – hydrogen and helium gas.
75. 5:11When these clouds of gas float around in space,
76. 5:15they slowly get pulled together by their own gravity
77. 5:18and start to spin.
78. 5:21The gas cloud spins faster as more material is
79. 5:25pulled into the centre and it flattens out into the
80. 5:29shape of a disc.
81. 5:31This is called an accretion disk.
82. 5:35The gas and dust get hotter and hotter as gravity
83. 5:39continues to squeeze it together.
84. 5:42Remember when we learned how all matter is made of
85. 5:45tiny things called atoms?
86. 5:48Atoms have little invisible force fields around them
87. 5:51that stop them from getting very close to each other.
88. 5:55But in the right conditions, they can be made to
89. 5:58smash together.
90. 6:01It’s sort of like if there are two cars driving down
91. 6:04the road with force fields.
92. 6:07At slow speeds, they will just push each other away
93. 6:10when they get close.
94. 6:13But if the cars are driving super fast, the force
95. 6:17fields will not be strong enough to keep the cars
96. 6:20apart and they will slam into each other with
97. 6:23incredible force.
98. 6:28When gravity squeezes the gas clouds,
99. 6:31the atoms will bump into each other which heats the
100. 6:34gas to extreme temperatures and makes the atoms move
101. 6:39around super fast.
102. 6:42Eventually the immense heat and pressure will force
103. 6:46two atoms to smash together to make a new,
104. 6:49heavier atom.
105. 6:52This process is called nuclear fusion and it releases
106. 6:56a bunch of energy.
107. 6:58This nuclear fusion energy pushes outward and
108. 7:02fights against the gravity.
109. 7:05The more the gas cloud is squeezed by gravity,
110. 7:09the more nuclear fusion energy is released, until
111. 7:12there is enough nuclear fusion to stop gravity from
112. 7:16squeezing it any further.
113. 7:19When the outward push of nuclear fusion equals the
114. 7:22inward pull of gravity, it creates a stable star!
115. 7:28Hey this looks kind of familiar.
116. 7:31It looks just like the sun!
117. 7:33That’s because the sun IS a star, just like the
118. 7:37thousands of tiny stars we see in the night sky.
119. 7:41It’s just way closer to us than any other star,
120. 7:45so it looks much bigger and brighter.
121. 7:50Our sun is a medium-sized star, but it's gigantic
122. 7:56compared to planet Earth.
123. 7:58If Earth was shrunk down to the size of a quarter,
124. 8:01the sun would be 2.6 meters tall!
125. 8:07Look how much bigger the sun is when Earth is placed
126. 8:10right next to it!
127. 8:12Whoa, the sun is HUGE!
128. 8:17The brightest star in our night sky (after the sun)
129. 8:20is called Sirius.
130. 8:23It burns hotter than the sun, so it
131. 8:25glows a bright blue colour and Sirius is about 1.7
132. 8:30times as big as the sun.
133. 8:32But these medium-sized stars are tiny compared to the
134. 8:37largest stars in the universe called hypergiant stars!
135. 8:43One of these hypergiant stars is called UY Scuti
136. 8:47and it’s estimated to be 1700 times bigger than the sun.
137. 8:53I’ve placed a scale model of sun and Earth right
138. 8:57beside UY Scuti to compare the size.
139. 9:01Can you find them?
140. 9:03There they are!
141. 9:05Let’s zoom out to see how big our Earth and sun are
142. 9:09compared this awesome hypergiant star!
143. 9:15Wow, our planet and sun are like tiny specks compared
144. 9:20to UY Scuti!
145. 9:23Awesome, we learned all sorts of cool stuff about how
146. 9:27stars are made and how they work.
147. 9:31But the coolest thing about stars is what happens when
148. 9:34they meet their demise!
149. 9:37Check out our next episode where we’ll explore the
150. 9:40universe to learn amazing facts about neutron stars,
151. 9:45black holes, and supernovas!
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