The countdown has finally begun for one of the biggest incidents of the century - the longest lunar eclipse.Lunar eclipse 2018 will occur on the late hours of July 27 early hours of July 28. The total lunar eclipse is a unique celestial phenomenon in which people will have a chance to take a glimpse of the so-called "blood moon", which is a phenomenon in which the mood looks red in colour. The chandra grahan will last for 1 hour and 43 minutes, wherein the moon will be in perfect alignment with the sun and Earth. The partial phases of this eclipse will last for a period of 6 hours. The event is much more than a one-night cosmic wonder. Before you get all excited about watching the blood moon, read these interesting science facts about lunar eclipse 

1. The moon orbits the earth around 12 times in a year. The occurrence of eclipse does not happen every time the moon orbits the earth. This is because orbital planes of the earth and moon differ only slightly. The two intersect at angle of around 5-degrees.

2. Simply put, this July lunar eclipse or chandra grahan will be such that the earth will come directly between the sun and moon. As a result, the sunlight will be blocked from reaching the moon's surface and will cast a shadow over it.

3. But the event will not be visible in all parts of the world, as is the case with most eclipses. But need not worry as India will fall under the zone in which the blood moon will be visible.

4. The story behind blood moon: During chandra grahan, the moon will be at farthest distance from the earth. As a result, revolution of the moon around the planet will seem slower than usual. As mentioned above, the moon will also fall under the region over which the earth casts its shadow. This region is known as the umbra. This will shield the moon from the sun for a much longer duration. A red light will be reflected of the moon's surface, and thus we all see a magnificent red or blood moon.

5. The tinge of light is because of an interesting fact. There are colours with shorter wavelengths and there are colours with longer wavelengths. Lights like blue are refracted at sharper angles and thus have shorter wavelights. Lights like red on the other hand, do not diverge very far from their original path and thus have longer wavelengths. Low-frequency waves refract just enough to pass the earth and land on the moon. This is the reason why lunar eclipses appear red.

6. Lunar eclipse 2018 is however, the second blood moon of 2018. Earth witnessed a "super blue blood moon" on the night of January 31. Many parts of the world were able to see the super blue blood moon.

7. People in India will be able to witness chandra grahan. Some parts of North-east India may not be able see the entire lunar eclipse. People in North America and north-western parts of South America will not be able to witness the event. Portions of the eclipse will be viewed by most parts of Europe, Australia, Japan, China and western Africa.

The blood moon will begin at 11.43 pm on July 27 and will end on 5.34 am on July 28.

Books are available in the Library on the Topic Lunar eclipse 2018, go through the books and write the reviews.

Name of the Book: Exploring Space

Author: Barbara Bourne, Wendy Saul

Name of the Book: Eclipse – A Celestial Shadow Play

Author: B. S. Shylaja, H R Madhusudan

Name of the Book: Universe

Author: Discovery Channel, Young Discoverer Series