Just after sunset on Tuesday, a rare kind of “blood moon” will hang in the northwestern sky over Hong Kong for almost an hour and a half.
There will not be another total lunar eclipse seen from Hong Kong until 2025. In a second, simultaneous celestial event, the blood moon at its peak will block views of the planet Uranus for 49 minutes.
Caused by an alignment that sees the moon drift into Earth’s shadow, this total lunar eclipse will have various phases, the most interesting of which is totality, when the lunar surface will turn red for 1 hour and 26 minutes. Here is everything you need to know to catch the stunning sight in Hong Kong.
What causes a blood moon?
A blood moon occurs for the entire night side of our planet when a full moon moves into the Earth’s shadow. That can happen only when the Earth is precisely between the sun and the moon.
It’s a reasonably rare event because the moon’s orbital path around Earth is inclined to the ecliptic – the path of the sun through the sky – so only occasionally is there a full moon in exactly the right position. From the moon there’s a total solar eclipse caused by the Earth.
The lunar surface turns red because the only light that reaches it has been filtered by the Earth’s atmosphere. Red light has the longest wavelength so it more easily travels through particles in our atmosphere. It’s effectively thousands of sunsets being projected onto the moon.
Why this blood moon is unique
Not only will Tuesday’s blood moon look red for a particularly long time, but it will also look very strange as it rises into the sky.
Moonrise happens at 5.37pm Hong Kong time on Tuesday, during which the moon will appear partially eclipsed, with only about three-quarters of its surface in Earth’s shadow.
At 6.16pm – with the full moon just eight degrees above the eastern horizon – totality will occur. As it does, the night sky will darken around the moon to reveal the planet Uranus on its left (eastern) side
Just a minute before the eclipse’s totality phase peaks, the moon will occult Uranus, hiding it from view until 7.47pm, when it will reappear from behind the lower portion (south) of the moon.
Here’s the full celestial schedule according to the Hong Kong Space Museum:
5.37pm – the full moon rises partially eclipsed
6.16pm – totality (a blood moon) begins
6.58pm – Uranus disappears behind the blood moon
7.42pm – totality ends and a partial eclipse begins
7.47pm – Uranus reappears
8.49pm – the partial eclipse ends
Where to watch the blood moon and occultation of Uranus
If you want to see the full moon rise partially eclipsed, it’s wise to position yourself somewhere high so you can see a clear eastern horizon.
In clear skies, the entire event will be visible to the naked eye, though to see both detail on the reddening lunar surface and Uranus clearly, use binoculars or a small telescope.
“Since the planet Uranus is a lot dimmer than the Moon, under most circumstances even if they are close together the former is often hidden in the latter’s glare,” reads the website of the Hong Kong Space Museum.
“Only in a total lunar eclipse when the brightness of the Moon drops significantly can we see the Moon and Uranus side by side.” Uranus will be visible as a tiny blue disc in binoculars or a telescope.
A three-hour live-stream of both the blood moon and the occultation of Uranus will be broadcast with commentary in Cantonese from 6pm until 9pm on the YouTube channel of the Hong Kong Space Museum.
Who else will see the super blood moon?
East and Southeast Asia, Australia, New Zealand, the Pacific Ocean and the Americas will all get some view of the total lunar eclipse.
Those in Hawaii arguably get the best view of the blood moon high in the sky in the middle of the night, although parts of the world will experience a “selenelion” eclipse, which is when both the sun and an eclipsed moon can be observed at the same time.
Russia and Southeast Asia will see an eclipsed moon rise during a sunset, while the east coast of North America – including New York – will experience an eclipsed moon setting during a sunrise.
Here’s when a blood moon will occur at local time in the Asia-Pacific region:
Manila, Philippines: 6.16pm-7.41pm PHST
Singapore: 6.46pm (moon rises eclipsed)-7.41pm SGT
Tokyo, Japan: 7.16pm-8.41pm JST
Sydney, Australia: 9.16pm-10.41pm AEDT
Auckland, New Zealand: 11.16pm-12.41am NZDT
Honolulu, Hawaii, USA: 12.16am-1.41am HST
Los Angeles, USA: 2.16am-3.41am PST
The next blood moon total lunar eclipse visible from Hong Kong will occur on September 8, 2025, during which a blood moon will be seen for 1 hour 22 minutes.