Science and Technology
In News: A rare spectacle of a “Beaver blood moon” was seen as the Earth, moon and sun align to produce a total lunar eclipse for the last time until 2025.
- This was the second blood moon of the year.
- It was visible across eastern Asia & Australia (in evening moonrise), the Pacific and North America (in early morning hours)
- It will be visible to the naked eye wherever skies are clear in those regions.
About:
- A total lunar eclipse occurs when the Earth casts its shadow completely over a full moon, blocking reflection of all direct sunlight from the lunar orb and dimming the colour of the moon to a reddish hue, hence the term “blood moon.”
- This is only possible when the orbits of the Earth, moon and sun align so that the moon is directly behind Earth relative to the sun.
- Moon’s orbit around Earth is usually tilted relative to Earth’s orbit about the sun. Hence, the moon passes above or below Earth’s shadow because of its orbit.
- Outer shadow is called “penumbra,” and the darker, inner shadow is called the “umbra,” before reaching totality.
- Reddish appearance of the lunar surface is caused by rays of sunlight around the outer edge of the eclipse shadow, or umbra, being filtered and refracted as it passes through Earth’s atmosphere, bathing the moon indirectly in a dim copper glow.
- Degree of redness depends on atmospheric conditions that vary with levels of air pollution, dust storms, wildfire smoke and even volcanic ash.
- Rarity: Total lunar eclipses occur, on average, about once every year and a half, but the interval varies.
- Beaver moon: is a moniker for November’s full moon adopted by the Old Farmer’s Almanac supposedly from Algonquian languages once spoken by Native Americans in the New England territory. When combined with the phenomena of a total lunar eclipse, it is widely referred to as a “Beaver blood moon” in the United States.
Source: Indian Express
Previous Year Question
Q.1) Consider the following phenomena:
- Size of the sun at dusk
- Colour of the sun at dawn
- Moon being visible at dawn
- Twinkle of stars in the sky
- Polestar being visible in the sky
Which of the above are optical illusions?
- 1, 2 and 4 only
- 3, 4 and 5 only
- 1, 2 and 4 only
- 2, 3 and 5 only
