An spectacular lunar eclipse will be taking place during the
night of 27-28 July. If weather permits,
the entire cosmic event will be visible from Srinagar and other parts of the
state. The penumbral eclipse will begin at quarter to eleven in night and end
after Fajr, making it longest eclipse of the century. The total eclipse will begin at quarter past
one and end at quarter to three. In the
night of the eclipse, full moon is also at its farthest from the earth (Apogee)
so it will look relatively smaller in the sky hence it is called micro moon in
contrast to supermoon when it appears largest.
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!
For sky-watchers there is another treat in the intervening
night of 27-28 July. The red planet Mars will be aligned with Earth and Sun.
Mars will be on the opposite side of the Sun and Earth and it will be visible
throughout night. It can be seen in the vicinity of eclipsed moon. In fact
Jupiter and Saturn will also be clearly visible during the night. It is summer
time hence night picnics may be organized by all science and nature lovers in
their neighbourhood. All astro-photographers, may aim their cameras towards sky.
The eclipse is a unique opportunity to appreciate, admire and celebrate the beauty and
inspiration of this celestial experience.
