Question

Astronomy 107

1) There are two different types of radiation produced by the Sun. What are they and how do they differ from each other? (Hint: consider the different layers of the Sun)

2) Is our star one of the most common stars in the universe? Why or why not?

3) We live in the habitable zone of our Sun. What will happen in a few billion years that will change this?

Answer 1

1) production of energy takes place at the core of the sun. here hydrogen undergoes fusion to produce helium and gamma rays. so the radiation type here is gamma radiation. As these photons(radiations) moves towards the photosphere(outer layer) they get scattered due to collisions in the high density inner layers. As a result of these scatterings, the wavelength of the outgoing photons changes from gamma range to visible, infra and ultraviolet range before exiting the outer surface of the sun and moving into the outer space. so at the outer layer of the sun the type of radiation is mostly visible radiation.

2) The most common type of stars are named as Red dwarfs(M type). these are smaller in size(0.2M_o to 0.4M_o) and hence burns its fuel at a slower rate at a lower temperature. therefore they live the longest among all the stars and hence the most common(more new stars are born before old ones die off, increasing its population gradually). Sun, on the other hand, is a yellow dwarf(G type). so we can conclude that sun is not one of the most common stars in the universe.

3) Our sun has already lived half of its life. In a few billion years it will transform from yellow dwarf into a Red Giant with increased size, luminosity as well as temperature. it will also probably engulf the closer planets, namely, mercury, venus and Earth. so then Mars will replace mercury as the closest planet and the habitable zone will most likely shift and encircle Jupiter.( jupiter becomes new earth).