Question

Multiple choice: Which one of the following statements about our Sun is true?

(a) The Sun consists primarily of hydrogen and helium.

(b) The Sun is a very active star, blasting waves of energy, solar flares, and winds continuously and uniformly with time.

(c) The apparent motion of sunspots on the Sun is caused mainly by Earth’s orbit.

(d) Being an uncharged (i.e., neutral) star, the Sun does not have a significant magnetic field.

(e) Sunspots were first discovered recently, using telescopes in space.

Multiple choice: Which one of the following statements about our Sun is true?

(a) Being farther from the center of the Sun, the chromosphere has a lower temperature than the photosphere.

(b) Sunspots appear dark because there isn’t any nuclear fusion occurring in them, unlike the case in the surrounding photosphere.

(c) The chromosphere appears reddish pink because it reflects Hα emission from the photosphere.

(d) Coronal mass ejections occur when the nuclear-fusion rate in the Sun suddenly increases by a large amount.

(e) The Sun’s rotation period can be determined by tracking the positions of long-lived sunspots.

Multiple choice: Which one of the following does not change during the course of one full 22-year solar activity cycle?

(a) The frequency of sunspots.

(b) The Sun’s overall magnetic field orientation.

(c) The Sun’s rotation speed.

(d) The frequency of coronal mass ejections.

(e) The frequency of prominences and flares.

Answer 1

Question 1 : True statement is a)

Reason, the Sun is mainly composed of hot gases along with plasma, where the proportion of hydrogen is 70% and Helium is 27% of the total mass, therefore Sun consists primarily of Hydrogen and Helium.

b) Though the sun is a very active star and blasts waves of energy, solar flares, and winds but it is not continuous and uniform with time. These solar activities depends upon the magnetic activity at different regions on sun.

c)The reason for apparent motion of the sunspots is due to the spinning of Sun in space. In fact the motion of the sun spots is an indication that sun is spinning in space.

d) The energy production in the sun takes place at its core due to nuclear fusion reaction. This releases tremendous amount of energy which gets converted into light, heat. Due to this, the temperature of the gases on the sun is increased to a large extent causing the electrons to be stripped away from the atoms resulting in formation of plasma. Thus plasma consists of many free charge particles. In the convection zone, plasma from below photosphere moves up due to convection. This moving free charges produces magnetic field. Thus the sun has a significant magnetic field.

e) Sunspots were discovered very long time ago. They were observed with naked eye approximately 2000 years back in China while in seventeenth century, the famous astronomer Galileo observed sunspots and their motion by using the telescope made by himself.