Astronomical knowledge

Nature photographers and other earth lovers always look forward to the blues moment, which is the transitional stage between day and night in the twilight-before sunrise or shortly after sunset, the sun is below the horizon, but the earth and the sky are still full of beautiful blue light.

After sunset on August 2 1, this photo taken in Nadam Pezzo, Corthie, Italy during the blues period captured a scene close to the full moon, when the moon was rising against the sun and hanging beside the rugged Italian Alps.

The pyramid-shaped peak in the picture is called Antrau Peak, also known as the king of dolomite. It is a famous alpine peak in this area and is shrouded in the same blue as the sky. The moonlight is yellow, but even so, this full moon is called seasonal "blue moon" by some people.

This is because there is a saying that if there are four full moons in a season, the third one will be called blue moon. If we define a season as the time between the solstice (summer solstice or winter solstice) and the neighboring vernal equinox (autumnal equinox or vernal equinox), then the fourth full moon of the current season will rise at the blues moment on September 20th-a little earlier than the autumnal equinox in September.

(Translation: Beijing Planetarium)