NCERT Solutions for Curiosity Chapter 13 Our Home: Earth, a Unique Life Sustaining Planet

About this chapter

All life on Earth exists in an astonishingly thin shell. From the highest peak to the deepest ocean trench is only about 20 km against an Earth radius of about 6400 km — if Earth were an apple, the crust would be the apple's skin. Earth lies in the habitable zone (or 'Goldilocks zone'), the range of distances from a star over which water stays liquid . Its nearly circular orbit keeps sunlight and heat steady through the year, so most places escape extreme summers and winters. Earth is also the right size . Its gravity is strong enough to hold on to the atmosphere — Mars's atmosphere is 100 times thinner and Mercury has none — but not so strong that our own weight would crush us. The atmosphere works in three ways: oxygen for respiration, the ozone layer (a three-atom form of oxygen) that b

• Chapter opener
• .1 Why Is Earth a Unique Planet?
• .2 What Do the Planets of Our Solar System Look Like?
• .3.1 Position of the Earth
• .3.2 Size of the Earth
• .3.3 Magnetic field of the Earth
• .4.4 The importance of balance
• .5 What Keeps Life from Disappearing?
• .5.1 Asexual reproduction
• Sexual reproduction in animals