An spectacular lunar eclipse will be taking place at moon
rise on Wednesday, January 31. The total lunar eclipse of 31 January 2018 will
occur during a “supermoon”, i.e., a full moon that coincides with perigee of
the moon (the closest distance that the moon comes to earth during its orbit
around the earth). The “super-moon” appears about 14% larger than a regular
full moon. Another coincidence is that the full moon of 31 January is also
talked of as a “blue moon” in the English media - a blue moon is said to occur
when two full moons occur in the same calendar month. Also, this supermoon is
the third in a trilogy of super moons, following those of 3 December 2017 and 1
January 2018.
It will be visible in
Jammu and Kashmir between 6:20 pm up to
8 pm. I am fascinated by moon since my childhood. When I was a youngster
my father brought for me a popular science book in Urdu ‘Nau Saiyare Ektis
Chand’. Through this book I came to know that moon is a non luminous body and
it shines by reflecting the solar light. I was so upset by this fact that I hid
the book lest others may know about the truth that moon does not have its own
light. I was naïve like any other child of my age.
A lunar eclipse occurs when the Moon passes behind the
Earth so that the Earth blocks the Sun's rays from striking the Moon. This can
occur only when the Sun, Earth, and Moon are aligned exactly, or very closely
so, with the Earth in the middle. Hence, a lunar eclipse can only occur during
the night of a full moon. It might be expected that during every full moon the Earth's shadow will fall on the Moon,
causing a lunar eclipse. Lunar eclipses are not observed every month
because the plane of the Moon's orbit around the Earth is tilted by about five
degrees with respect to the plane of Earth's orbit around the Sun. Thus, when a
full moons occurs, the Moon usually lies to the north or south of a direct line
through the Earth and Sun. Although a lunar eclipse can only occur when
the Moon is full, it must also be positioned very near the intersection
of Earth's orbital plane about the Sun and the Moon's orbital plane about the
Earth that is, at one of its nodes.
The shadow of the Earth can be divided into two distinctive
parts: the umbra and penumbra. Within the umbra, there is no
direct solar radiation. Due to the Sun’s large angular size, solar light is
only partially blocked in the outer portion of the Earth’s shadow or penumbra.
A penumbral eclipse occurs when the Moon passes through the Earth’s
penumbra. A partial lunar eclipse occurs when only a portion of the
Moon enters the umbra. When the Moon travels completely into the Earth’s umbra,
one observes a total lunar eclipse.
Unlike a solar eclipse, which can only be viewed from a
certain relatively small area of the world, a lunar eclipse may be viewed from
anywhere on the night side of the Earth. A lunar eclipse lasts for a few hours,
whereas a total solar eclipse lasts for only a few minutes at any given place,
due to the smaller size of the moon's shadow.
Since moon is a non luminous body, lunar eclipses (unlike
Solar Eclipses) are completely safe to observe with the naked eye - no special
equipment or filters are needed. Sometimes a Total Lunar Eclipse is best viewed
without any optical aid, and just lying under the stars watching the change as
the Moon first gets slightly darker (penumbral phase), then starts to get eaten
away (partial phase), finally turning deep red or copper coloured as it enters
totality. During a total lunar eclipse, the sun’s direct light is blocked by
the earth and does not reach the moon. A small amount of the sunlight that
passes through earth’s atmosphere, however, is refracted or “bent” towards the
moon by the atmosphere and is reflected towards us on earth by the moon.
Particles in the atmosphere also preferentially scatter away the bluer light of
shorter wavelengths and only the redder light that has relatively longer
wavelengths gets through, similar to the sunlight we see at sunset and sunrise.
This redder light reaches the moon because of the bending (refraction).
Therefore the moon appears copper-coloured during a total lunar eclipse. The
exact colour will depend on the nature and quantity of the dust particles,
water droplets and aerosols present in the earth’s atmosphere at that time. Hence
it is an indicator of earths atmospheric pollution!
The eclipse is a unique opportunity to admire and celebrate
the beauty and inspiration of this celestial experience. It is also preferable to offer two rak’aat Salate Khusoof.
