Question

A 400 km thick, bright layer around the sun is known as _________.
A. Photosphere
B. Chromosphere
C. Terrestrial
D. None of these

Answer 1

Hint:- The sun is an ordinary star like other stars in our galaxy. It is a hot ball of gases and lacks a solid surface. It was born about 4.5 billion years ago. Life on earth is impossible without the sun as it is the only source of heat and light, the two main prerequisites for life to sustain.

Complete step-by-step solution:-
The sun’s atmosphere is composed of six layers. These include the innermost core, radiative zone, convective zone, photosphere, chromosphere, and outermost corona. Of these the outer three layers i.e. photosphere, chromosphere, and the corona receive energy from the inner layers. We see this energy reaching us in the form of sunlight.
The photosphere is that layer of the sun which is visible to our eyes. It is the lowest layer of its atmosphere just beneath the chromosphere. It is about 400 km thick. This layer is extremely white and slowly becomes opaque to the human eyes. This is why beyond this layer we cannot see the sun. The photosphere receives energy from the core which in the form of photons moves towards the solar surface and radiates out as light energy. A ray of light takes 8 minutes to reach our planet earth. The solar flares that we observe on the outer atmosphere of the sun originate from the photosphere. The flares produce X-rays, UV radiations, electromagnetic radiations, and radio waves.
So the correct answer is option (A), Photosphere.

Additional information:-
The distance of the sun from our earth is about 150 million kilometers. As the sun rotates on its axis, it shows differential rotation. This is because its different layers rotate at different speeds. The solar poles take more than 30 days to complete one rotation whereas the equatorial region takes only 24 days.

Note:- The photosphere’s bright light is due to bubbling particles of Plasma. It also contains dark and cool sunspots. These sunspots appear on the photosphere when the sun’s magnetic field is disrupted on the surface.