Presentation is loading. Please wait.

Presentation is loading. Please wait.

Stars.

Similar presentations


Presentation on theme: "Stars."— Presentation transcript:

1 Stars

2

3 What powers a star? A star is ‘powered’ by nuclear fusion reactions in its core. Nuclear fusion involves light atomic nuclei joining together to form heavier ones. Each fusion reaction produces a small amount of energy, but there are billions of reactions per second. Each second, the Sun produces 4 × 1026 joules of energy. It would take 2,000 million nuclear power plants a whole year to produce the same amount of energy on Earth. Photo credit: © Tom Tschida/NASA In the Sun, and in most stars, hydrogen atoms fuse together to form helium. This provides the energy for life on Earth.

4 How are elements made? Nuclear fusion in stars produces new atoms.
In the early stages of a star’s life, nuclear fusion mainly produces light elements such as helium. When all the hydrogen has been used up, other elements are fused together to make the heavier elements of the periodic table. Photo credit: NASA Headquarters - Greatest Images of NASA (NASA-HQ-GRIN) The Ring Nebula as imaged by the Hubble Space Telescope. The nebula is around one light year in diameter and is 2,000 light years from Earth. The blue areas of the nebula show the presence of superheated helium gas clouds, and the red and green areas show ionized oxygen and nitrogen. However, not all elements are made in the early stages of a star’s life. Some of the heavier elements are only made when a star explodes at the end of its life.

5 Heavy elements on Earth
Photo credit: © gary718, Shutterstock.com 2011

6

7 The life cycle of a star Every star goes through a life cycle. A star’s life cycle is determined by its size. neutron star red super giant super nova black hole main sequence star white dwarf black dwarf red giant

8 How do stars begin and end?
Teacher notes This animation introduces how stars are formed, and how small, massive and really massive stars die.

9 Life cycle of small stars
Teacher notes This ordering activity could be used as a plenary or revision exercise on the lifecycle of small stars, and the difference between small stars and large stars in the following activity. Mini-whiteboards could be used to make this a whole-class exercise.

10 What is a supernova? Teacher notes
This seven-stage animation explains what a supernova is and the stages in its formation.

11 How are black holes formed?
The end of the life cycle of really massive stars is different to that of massive stars. After a really massive red giant collapses in a supernova explosion, it leaves an object so dense that nothing, not even light, can escape its gravitational pull. This is called a black hole. Some scientists believe that there are black holes at the centre of galaxies. Photo credit: NASA Headquarters - Greatest Images of NASA (NASA-HQ-GRIN) The spiral galaxy NGC 4414 as imaged by the Hubble Space Telescope. The core of the galaxy contains mainly older yellow and red stars. The outer spiral arms contain young, blue stars. The outward spiralling arms of the galaxy are very rich in interstellar dust. If light cannot escape from a black hole, then how can a black hole be observed? 11

12 How can a black hole be ‘seen’?
Teacher notes This three-stage animation explains how we know black holes exist, and where, even though they cannot be seen. 12

13 Life cycle of large stars
Teacher notes This ordering activity could be used as a plenary or revision exercise on the lifecycle of large stars, and the difference between large stars and small stars in the previous activity. Mini-whiteboards could be used to make this a whole-class exercise.

14 Terms about the life cycle of stars
Teacher notes This matching activity could be used as a plenary or revision exercise on the life cycle of stars. Students could be asked to complete the questions in their books and the activity could be concluded by the completion on the IWB.

15 Stars life cycle summary

16 The worksheet ‘Stars’ accompanies this presentation.

17 Glossary Teacher notes
black hole – An object whose gravitational pull is so strong that nothing can escape, not even light. It is formed after a really massive star collapses in a supernova. galaxy – A vast collection of millions of stars. nebula – A massive cloud of gas and dust in which a star is formed. neutron star – The very dense core that remains after a massive red giant collapses in a supernova. nuclear fusion – The process in which lighter atomic nuclei join together to make heavier atomic nuclei and a massive amount of energy is released. red giant – The huge red star formed when a star expands and shines less brightly as it starts to die. supernova – The huge explosion that occurs when a massive red giant is at the end of its life. white dwarf – The core that remains after the outer layers of a small red giant drift away.

18 Anagrams

19 Multiple-choice quiz Teacher notes
This multiple-choice quiz could be used as a plenary activity to assess students’ understanding of stars. The questions can be skipped through without answering by pressing the forward arrow. Students could be asked to complete the questions in their books and the activity could be concluded by the completion on the IWB.


Download ppt "Stars."

Similar presentations


Ads by Google