Chapter 10, Problem 1RQ

What is a habitable zone, and how is the idea useful? Is a planet in the habitable zone necessarily habitable? Explain.

To determine

The definition of the habitable zone with its usefulness and discuss the habitability of the planets belonging to the same habitable zone.

Answer to Problem 1RQ

Habitable zones are the area around the central star which has an possiblity of supporting life. Every planet present in an habitable zone does not neseccarily support life as there are various other factors which are required for life to exist on a planet.

Explanation of Solution

Habitable zone is an area around a particular star i.e. the orbital region which has an ability to support different forms of life. The sustenance of life on a particular planet is determined by presence of the various life supporting matters such as water, oxygen, carbon dioxide etc. The planets belonging to the same habitable zone has a higher possibility of life sustenance as the conditions they are exposed to is similar.

All the planets present in a habitable zone does not necessarily support life because there are various other factors which is helpful to determine the habitability of the planet. Factors which are necessary to support life on a planet is as given below.

Luminosity- It is defined as the brightness of the planet in other words the temperature on the planet.

If the solar system in which the sun is the central star is considered, the luminosity of the planets can be determined by the distance of the planets from the sun.

To maintain an optimum temperature the planet need to be in a region which is neither too close to the sun nor too far. Closeness to the sun makes the planet hotter and the distant planets are at very lower temperature. Thus luminosity which can be determined by the distance from the sun plays an important role in sustenance of life.

Size of planet- Except the distance of the planet from the central star, its size plays an important role to sustain life. The planet needs to be large enough to retain heat and to bear plate tectonics to regulate the climate.

Atmospheric conditions- The atmosphere on the planet should be sufficient to retain the liquid water on the surface. Also its presence prevents the exposure of the life to various harmful radiations which play a vital role of existence of life on the planet.

Conclusion:

Thus, habitable zones are the area around the central star which has a possibility of supporting life. Every planet present in an habitable zone does not necessarily support life as there are various other factors which are required for life to exist on a planet.