Page 28 - Dream June 2020

ANNULAR S LAR ECLIPSE PRECAUTIONS
Solar Eclipse
and Safety of the Eye
WK.B. Bhushan
e will have an opportunity to watch an Annular Solar Eclipse on 21 June 2020, mainly from the northern states like Rajasthan, Haryana, and Uttarakhand. The path of annularity will pass
through these states, though a partial eclipse will be visible from other parts of India including the southern states like Tamil Nadu. It is an excellent opportunity for all of us to witness this celestial drama of light and darkness. After 21 June, the next solar eclipse will be seen from Indian soil only after a decade. So better be ready to watch this annular eclipse, though in a safe way.
Looking at Sun during an eclipse or otherwise is dangerous. The safest way is to watch the eclipse indirectly, by projecting the image of the Sun using a small mirror or telescope (both Galilean and Newtonian) projection method. But watching a solar eclipse directly using a certified filter is undoubtedly a lifetime experience. However, the intrinsic human curiosity has forced many to observe solar eclipses without any safeguard or by other unsafe means. Lack of scientific information on safe viewing of an eclipse may cause serious injury to the eyes (also known as eclipse blindness), which may be temporary or permanent. It is also known as solar retinitis in the medical terminology. Careless viewing of solar eclipses has brought to light many such harmful effects. It is often believed that during an eclipse the Moon blocks enough of Sun’s light, making it safe to look at directly. However, except during totality, when the entire Sun is blocked out, the level of light and heat radiation coming from the Sun remains dangerously high.
There are several factors responsible for the damage caused to the eyes by unprotected observation of the Sun. To get an insight into how solar radiation during a solar eclipse can affect the eyes, we need to have a look at the structure of the eye.
Eye anatomy and the process of vision
Before we see anything, several small processes occur at an incredibly high speed. In order for us humans to see an object, light must fall on it to illuminate it. The object then automatically reflects part of the incident light which then enters our eyes when we look at it. The light first passes through the transparent cornea in the front part of our eye and enters the pupil, the black “hole” in the middle of the eye.
Careless viewing of solar eclipses has brought to light many harmful effects. It is often believed that during an eclipse the Moon blocks enough of Sun's light, making it safe to look at directly. However, except during totality, when the entire Sun is blocked out, the level of light and heat radiation coming from the Sun remains dangerously high.
28 dream2047/june2020