Class 8 Science Chapter 13, Our Home: Earth, a Unique Life Sustaining Planet, is the concluding chapter of the middle-stage Curiosity series. It brings together physics, chemistry and biology to explain why Earth supports life, how reproduction keeps life going, and the environmental threats our planet faces.
What Class 8 Science Chapter 13 Covers
13.1–13.2 A unique planet: Earth is the only planet known to support life. The chapter recalls the eight planets in order from the Sun, and Activity 13.2 has you compare each planet’s temperature, size and atmosphere.
The habitable zone: Earth sits at just the right distance from the Sun for water to stay liquid. Any closer and the water would boil away; any farther and it would freeze. This band is the habitable or ‘Goldilocks’ zone, and so much water is what makes Earth look blue from space. Mars lies at the edge of the zone; it may once have had lakes, but no proof of life has been found.
13.3 What else makes life possible: a nearly circular orbit keeps the seasons from swinging to extremes. Gravity is strong enough to hold the atmosphere but not so strong that living things would be crushed. The ozone layer blocks ultraviolet rays, the magnetic field turns away high-energy particles, and the greenhouse effect keeps the planet warm enough.
13.4 Sustaining life: the atmosphere, hydrosphere, geosphere and biosphere interact, cycling water and nutrients between living and non-living things.
13.5 Reproduction: without reproduction life would vanish. Asexual reproduction copies a single parent: a money-plant cutting, the ‘eyes’ of a potato or a piece of ginger (Activity 13.3), bacteria and amoebae splitting in two, hydra budding. Sexual reproduction brings new features into each generation, and the embryo develops inside or outside the body depending on the animal.
13.6 The triple planetary crisis: climate change from burning fossil fuels, biodiversity loss when habitats are destroyed, and pollution that causes smog and acid rain. The chapter, and the Grade 8 book, closes with ‘It’s never the end, my friend!’
Exercises in Chapter 13
- Give one major reason Mars cannot support life today.
- List features of Earth that we take for granted, such as air that does not escape into space.
- Grow new plants from a money-plant cutting, potato eyes or ginger and record what you see.
Read Class 8 Science Chapter 13 Online
More Chapters
- Previous: Chapter 12: How Nature Works in Harmony
- Hindi medium: Class 8 Science Chapter 13 PDF in Hindi (Jigyasa)
- All Science chapters and the other Class 8 books: Class 8 NCERT books 2026-27
- All Class 1 to 12 NCERT Textbooks: NCERT Books PDF (Class 1–12)
FAQ
What is the habitable or Goldilocks zone?
The range of distances from a star where the temperature lets water stay liquid; Earth lies inside it, Mars at its edge.
What is the triple planetary crisis?
Climate change, biodiversity loss and pollution, the three human-caused threats to life on Earth named in Chapter 13.
What is the difference between asexual and sexual reproduction?
Asexual reproduction needs one parent and makes exact copies; sexual reproduction lets new features appear in the next generation.