The term 'blood' or 'bloody' as applied to a fully eclipsed Moon, invoking images of horror and fright, is shunned by most astronomers, both professional and amateur. It is a description that our nearest terrestrial neighbour doesn't befit any time.
Only poets, soothsayers, storytellers and occultists are fond of it. The technically correct term is 'copper-red' or 'coppery red', and it is generally a dull red or orangish red.
However, someone with dichromatic vision like me (belonging to eight percent of the male population) is not the type to offer any definitive judgement. Plain red will do for me. No blood need to be shedon this count.
Solar and lunar eclipses as seen from the Earth would not have been possible at all but for a very fortuitous and remarkable circumstance relating to the three celestial bodies. The apparent sizes of the Sun and the Moon as seen by us on Earth just happen to be nearly the same, approximately half a degree in angular diameter.
When the Earth comes between the Sun and the Moon as on a full moon day, the latter can be found in the shadow of the Earth, and hence sunlight will not be falling on it directly. This is when a lunar eclipse occurs. As seen from any point on the Earth, the eclipse may be partial or total.
One might expect the Moon to be completely hidden from view during a total lunar eclipse. However, the whole of the Moon can be seen clearly as a faint coppery red object because of sunlight scattered by the Earth's atmosphere, predominantly in the red, falling on the lunar surface and thereby illuminating it.
It is a wonderfully beautiful sight to behold. During the eclipse, the Moon itself will be located within the umbral shadow of the Earth as illustrated in Fig.1.
Fig. 2 is a picture of how the Moon looked near totality during one of the numerous previous total lunar eclipses. The actual appearance and colour depend on the level of dust in the atmosphere where the phenomenon is observed.
When and where
Avid night sky watchers are waiting for another great opportunity to see a total eclipse of the Moon early in the night of 7-8 September this year, just a few days from now.
If the recent pattern of dismal weather allows a window of opportunity, the event should be visible from everywhere in the country. Unlike a total solar eclipse that lasts at best a few minutes, a total lunar one lasts much longer. The duration of the totality of the forthcoming one will be about 80 minutes. Again, very much unlike total solar eclipses, the lunar eclipse can be observed over a vast stretch of the Earth's surface.
How to see the eclipse
Watching a bright full Moon and a lunar eclipse that follows on the same night is exciting. Both the partial and total phases can be distinguished quite easily with the naked eye from a convenient vantage point, even in light-polluted urban environments. If it is a clear night sky in a location sufficiently far away from disturbing lights, the effect is all the more impressive. Unlike during a solar eclipse, no filters or optical aids are necessary, but a pair of binoculars, even small ones, enhances the view considerably.
A good 7×50 or similar low-powered binoculars provides a superb view, almost as good as the one through a small telescope with a large field of view, enveloping all of the lunar disk. The dull red hue of the lunar surface is significantly accentuated in such a view.
Total lunar and solar eclipses
Total solar eclipses at any given location are extremely rare events, with a frequency of one in about 375 years. It is therefore no surprise that a place like Mysuru has not seen one in living memory (an annular solar eclipse was visible on Dec. 26, 2019, but weather played spoilsport).
In contrast, total lunar eclipses are far more frequent, typically a few times per decade. The disparity arises because a total lunar eclipse is visible from the entire hemisphere of Earth experiencing night, whereas a total solar eclipse is visible only over a very narrow path on Earth's surface.
A plea for reason
Eclipses and similar natural phenomena have, across civilisations, given rise to a vast storehouse of irrational beliefs, myths, and superstitions. No system of knowledge has been completely immune to these influences, and modern media too often fuel rather than dispel them. In our society, people are even discouraged from witnessing these spectacular celestial events directly.
Most such beliefs are fanciful creations of the human mind, lacking any tangible evidence consistent with the scientific method of inquiry. The forthcoming lunar eclipse, therefore, should be seen as an opportunity not just to marvel at one of nature's most awe-inspiring spectacles, but also to strip away the layers of myth and superstition that obscure it. The plain truth is that eclipses bear no connection whatsoever to everyday human affairs. To suggest otherwise is nothing less than an eclipse of reason itself.
[The author is a former Professor of Physics and Principal of RIE Mysore and an amateur astronomer who loves watching celestial events, particularly total solar eclipses in different parts of the world. His writings can be accessed at: https://drsnprasadmysoreindia.blogspot.com/ ]