Whenever a lunar eclipse approaches or a striking full moon fronts the homepage, Bing runs moon questions. The centrepiece is always the same: why the Moon turns red during a total eclipse. Learn that one mechanism and most of the quiz falls into place.
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Why the Moon turns red
A lunar eclipse happens when Earth passes directly between the Sun and Moon, casting its shadow across the lunar surface. The Moon glows red, the 'blood moon', because Earth's atmosphere bends and filters sunlight, letting mostly red wavelengths through, the same scattering that colours sunsets.
Eclipse types and safety
Total, partial and penumbral are the three lunar eclipse types, depending on how deeply the Moon enters Earth's shadow. Unlike a solar eclipse, a lunar eclipse is completely safe to watch with the naked eye, and Bing likes testing that difference. Lunar eclipses only occur at full moon; solar eclipses only at new moon.
Phases and supermoons
The Moon cycles through its phases in about 29.5 days. A supermoon is a full moon near the Moon's closest approach to Earth, appearing slightly larger and brighter. Questions also touch on the Moon always showing the same face to Earth, because its rotation is tidally locked to its orbit.
Answering on eclipse days
If the homepage shows a red moon, expect the blood-moon question, the answer is Earth's shadow plus atmospheric scattering. For dates and visibility questions, a quick search of the specific eclipse confirms when and where it can be seen.
Frequently Asked Questions
Why does the Moon turn red during a lunar eclipse?
Earth blocks direct sunlight and its atmosphere filters and bends the remaining light, letting mostly red wavelengths reach the Moon, creating the 'blood moon'.
Is it safe to watch a lunar eclipse?
Yes, completely safe with the naked eye, unlike a solar eclipse, which requires eye protection, a favourite Bing comparison question.
What is a supermoon?
A full moon that coincides with the Moon's closest approach to Earth in its orbit, making it appear slightly larger and brighter than usual.