The full Moon of this Friday, May 5, will pass into eclipse – very slightly!
The Moon descends south across the ecliptic about 17 hours before encountering Earth’s shadow, so it traverses only the penumbra, or outer shadow, as shown in this diagram from page 99 of Astronomical Calendar 2023.
A scarcely discernible spectacle, and it will be centered over the Indian Ocean.
From anywhere within this “almost shadow (as paene umbra means in Latin), part of the Sun can be seen – a large part in the outer penumbra, a mere speck in the inner penumbra. But the Sun’s surface is so brilliant that even this speck gives a kind of daylight, as it does on Earth when the Sun is setting. So the part of the full Moon in the outer penumbra seems hardly dimmed at all; only the inner fraction, near the Moon’s north pole, will betray a subtle gray.
Just possibly, alert observers in Australia, India, or Africa will be able to testify that an eclipse really happened.
Eclipsed books
Don’t forget your chance to revisit the glorious eclipses of the past by acquiring the Astronomical Calendars of past years.
__________
This weblog maintains its right to be about astronomy or anything under the sun.
The maximum penumbral eclipse occurs here at 3.23am. I don’t feel the need to get up and look.