Earthshine, often known as "Da Vinci glow," is a phenomena in which
sunlight is twice reflected, softly illuminating the black limb of the
crescent moon right before and after the new moon.
On several days this week and once again the next weekend, the dark limbs
of the moon will exhibit the "Da Vinci glow" phenomena.
The soft light, commonly referred to as "Earthshine," is sunlight that is
first reflected by Earth onto the surface of the moon and then into the
observer's eyes. The result is a hazy, spectral light on the shaded side of
the moon that faces Earth.
Only when a thin crescent moon is visible near the horizon during both the
final few days and the first few days of the moon's orbit of Earth, which
occurs this week, is it feasible to see Da Vinci shine.
According to NASA(opens in new tab), Leonardo da Vinci gave the phenomena
its name when he hypothesized that it was the result of sunlight reflecting
off the Earth's seas and illuminating the moon's black surface in the 15th
century.
According to NASA(opens in new tab), clouds and sea ice are really the main
contributors of Da Vinci light.
According to
Almanac.com, "Da Vinci glow" is also referred to as "moon glow," "ashen glow," and, in
mythology, either the "new moon in the old moon's arms" (for a waning
crescent moon) or the "old moon in the new moon's arms" (for a waxing
crescent moon).
On May 19, there will be a new moon, but it won't be visible since it will
be nearly halfway between Earth and the sun and will be obscured by its
glare. The old moon and new moon are often too small, too dark, and too low
in the sky to be viewed without a telescope the morning before and the
evening following.
If the sky are clear, it will be possible to see Da Vinci shine in the
mornings for a few days prior to the new moon and in the evenings for a few
days thereafter.
This week, around the hour before sunrise in the eastern sky, you may see
the Da Vinci light on the moon:
Waning crescent moon with a 22% illumination on Monday, May 15.
Tuesday, May 16: Waning crescent moon, lit at 14%
Wednesday, May 17: Waning crescent moon, 7% lit.
Next weekend, at about an hour after sunset, you may see the Da Vinci shine
on the moon in the western sky:
5%-illuminated waxing crescent moon on Sunday, May 21.
Monday, May 22: A waxing crescent moon with 10% illumination
Tuesday, May 23: The best way to view the 17%-illuminated waxing crescent
moon near to Venus' Da Vinci glow is with the naked eye, any pair of
astronomy binoculars, or a decent small telescope.
The optimum time to view it in 2023, according to
Timeanddate.com, is in the few days
before and following the new moon on April 20 and May 19. According to
NASA, the reflected light is 10% brighter than usual during those months.
The phenomena, though, could be in danger. According to researchers at the
Big Bear Solar Observatory in California, the number of low clouds over the eastern Pacific
Ocean is decreasing as seas warm. This, in turn, results in a minor decrease
in Earth's reflectiveness and, therefore, the intensity of the Da Vinci
glow.
