A partial lunar eclipse was be visible in Hong Kong on November 19 2021 (Friday). This was the second lunar eclipse in 2021, after the first one in May. Members of the public enjoyed this event during the evening when the Moon rose from the east-northeast horizon. At the time of moonrise at 5:38pm that day, the "maximum eclipse" stage had already ended. The Moon was leaving the umbra gradually and the partial eclipse ended at 6:47pm when the Moon exited the Earth's umbra completely. The whole eclipse ended when the Moon leaves the penumbra at 8:06pm.
During the partial lunar eclipse, the Moon would not be completely covered by the Earth's umbra. However, since the Moon was at a low altitude and the sky was not completely dark when the eclipse was in progress, it took a bit longer to pin down the Moon. At 6:00pm that day, the Moon was still less than 5 degrees above the horizon, so special attention should be paid to the height of obstacles in the east-northeast direction when selecting a site for observation.
Type: Partial lunar eclipse
Main Visible Area: America, Pacific Ocean, East Asia, Australia, Northern Europe
This video simulates the telescopic and naked eye views of the partial lunar eclipse observed in Hong Kong.
When the Sun, the Earth and the Moon are aligned, the Moon will enter the Earth's shadow, resulting in a lunar eclipse. Depending on how the Moon comes in contact with the Earth's shadow, lunar eclipses can be divided into three types, namely the penumbral eclipse, partial eclipse and total eclipse. A penumbral lunar eclipse happens when the Moon enters the penumbra of the Earth; whereas a partial lunar eclipse happens when only part of the Moon enters the umbra. When the Earth's umbra covers the Moon completely, a total lunar eclipse results. A partial lunar eclipse can be divided into five stages: Moon enters penumbra, Moon enters umbra, Maximum eclipse, Moon exits umbra and Moon exits penumbra. Only the last two stages can be seen in Hong Kong during the partial lunar eclipse this time.
These two images were taken during the phase of the penumbral lunar eclipse before the partial lunar eclipse on 7 August, 2017. The image on the left was taken 1 hour before the partial eclipse. The image on the right was taken 10 minutes before the partial eclipse. The penumbral lunar eclipse is not obvious at its early stage. When the partial eclipse approaches, it can be seen easily that the surface of the Moon is dimmer.
The Hong Kong Space Museum live-streamed the partial lunar eclipse via its YouTube channel. Curators introduced the science behind lunar eclipse and shared interesting tidbits related to this astronomical phenomenon.