A ‘Blood Moon’ is coming this week - and will be should be visible to those on the west coast of America and Australia - as well as anyone on the Pacific Rim. This spectacular event where the full moon appears red is caused by a total lunar eclipse - where the moon is completely shadowed by the Earth.
This will be the first total lunar eclipse since January 2019, will occur during the full moon on the night of May 25-26 2021 – and this will also be the year’s biggest ‘supermoon’. Although the Moon’s orbit around Earth is a global phenomenon with a global schedule, whether our satellite will be above the horizon when it begins to turn strange colors will depend on shadows, angles and the quality of light visible where you are on the planet. Clear skies allowing, of course.
For those in the Pacific Rim, including much of western North America and Australia, it will afford an opportunity to create some special nightscape photos, with a setting ‘red moon’ in the ‘blue hour’ on the cards. But before we turn to photography let’s consider just what’s going on here, who’s going to see what, and when…
What is a total lunar eclipse?
Also called a ‘Blood Moon’, a total lunar eclipse is caused by a full Moon passing through Earth’s shadow in space. The Moon orbits Earth every 27 days, during which time it passes roughly between the Earth and the Sun (an invisible New Moon) and, 14 days later, moves to the other side of Earth to the Sun (a full Moon). The latter sees its near-side 100%-lit by the Sun, but just occasionally it travels precisely through the middle of Earth’s dark circular shadow in space.
• See also How to photograph the solar eclipse this June
When that happens – something that can take hours – the only light that can reach the lunar surface has first been filtered through Earth’s atmosphere. Short-wavelength blue light from the Sun tends to hit particles in Earth’s atmosphere whereas longer-wavelength red and orange light mostly travels right through.
The result, of course, is a ‘Blood Moon’, though in truth it’s more of a copper-reddish color.
Since the Moon is only going to just about enter, then quickly exit, Earth’s central shadow early in the morning of May 26 2021, this colored ‘totality’ will last only 14 minutes and 30 seconds. So photographers will need to be prepared well in advance.
• Read more: How to create a moonstack
What is a ‘supermoon’ and a ‘Flower Moon’?
The term ‘supermoon’ simply means a bigger-than-average full Moon, though the one on May 26 2021 will be the biggest of the year. That’s because the ‘Flower Moon’ – the traditional name for May’s full Moon – occurs while our satellite is at the closest point to Earth in its monthly orbit. That happens once every month because the Moon has a slightly egg-shaped orbit around Earth.
On May 26, 2021, everyone on the planet will get to see – if skies are clear – a supermoon. The key time to see and photograph that will be at moonrise in the east. So check the sunset and moonrise times where you are. However, only the Pacific Rim will see the ‘Blood Moon’.
Why does the moon go red?
As it begins to enter the dark shadow of Earth, one edge of the moon begins to look pinky-orangey-brown, changing to red as the event peaks. Once it has entered into that darkest zone of the shadow, it’s what's called totality, where sunlight is being bent through the Earth’s atmosphere and on to the moon.
So, much like a sunset is red because the light that’s entering your eyes is travelling through a lot of the Earth's atmosphere, so the light projected onto the lunar surface is also red. The physics is much the same.
Where and when to see the ‘Blood Moon’
This ‘Blood Moon’ will be most easily seen in its entirety from the West Coast of the U.S., Mexico and South America (just before moonset in the west, close to dawn), Hawaii, Australia and New Zealand (high in the sky in the middle of the night) and eastern Asia (just after moonrise in the east, close to dusk) – essentially around the Pacific Rim. However, those in central North America will be able to see some of the total phase just before the Moon sinks in the west.
Will you see it? You can easily find out exactly what time the ‘Blood Moon’ will be visible from any location. Ignore the times for the ‘penumbral’ eclipse (the Moon merely dulls slightly as it enters Earth’s fuzzy outer shadow), but be outside for the 87 minutes long ‘partial’ eclipse to watch the Moon start to go red. The division between bright and dark red can make an excellent close-up.
However, ‘total eclipse begins’ is the time you need to be ready for – and that’s 11:11 Universal Time on May 26 2021. Take into account how high the Moon will be in the sky (its altitude) and also note its compass direction. One interactive Google Map of this eclipse has useful links to PeakFinder (hit the ‘U2’ and ‘MAX’ links in the pop-up data boxes).
How to photograph the ‘Blood Moon’
Total lunar eclipses are often long, lazy spectacles where you can try a few things out, fail, and try again. Not so this one, so you need to make a plan and practice beforehand focusing your camera and changing settings manually.
A ‘Blood Moon’ is much easier to photograph than a solar eclipse, but this one is very short; you have less than 15 minutes to get a good shot of a copper-colored lunar surface. What’s more, the Moon’s path will just skim near the inner edge of the Earth’s dark shadow, so the top half of the Moon is expected to remain rather bright.
The most important thing you need? A clear sky. This is your number one priority. Check the weather reports and be mobile in the hours beforehand to maximize your chances. The west coast of the United States and Hawaii have the highest chances.
Equipment you’ll need, how to focus, and settings
For a close-up of the Moon you’ll need a DSLR or mirrorless camera with a 300mm telephoto lens on a tripod - but ideally one that is at least 600mm long. Alternatively a bridge camera, with its built-in superzoom will do the trick. Be sure to properly focus your lens. Using infinity focus might work, depending on your lens. An alternative that will work for all lenses is to use your camera’s LCD screen to look at part of the Moon zoomed-in, and then to focus until sharp (either manually or using auto-focus, though if the latter you must then switch to manual mode to prevent your camera from refocusing for your next shot).
With a shutter delay set, and shooting in RAW, during totality keep the aperture as wide as possible (a low f-number), begin with ISO 800 and use a fast shutter speed – about 1/100sec – to keep the shot sharp. It’s all a trade-off between ISO and shutter speed, but a Lunar Eclipse Exposure Calculator will help you figure out base settings for your lens. Bracketing either side of your target exposure is the way to go.
However, the low altitude of this eclipse as seen from the western U.S. does present a chance to snap a ‘Blood Moon’ with a foreground, or within a landscape composition. So bring a wide-angle lens, too.
How to photograph the ‘Blood Moon’ and the Milky Way
A nice bonus during a total lunar eclipse that often gets overlooked is how the Milky Way often appears as the Moon’s bright light is dulled. The Milky Way is usually photographed during a new moon, but a total eclipse allows you to shoot our galaxy in a different way. During the eclipse the Moon will be in Scorpius, about 20º west of our galaxy’s arc, so from a dark sky site your camera may be able to find the summer Milky Way just for a few minutes during totality. So consider a second camera fitted with a wide-angle lens at its wide aperture, and shoot at ISO 400 with varying – but much longer – shutter speeds of up to 30 seconds.
How to photograph the ‘supermoon’ at moonrise
Here’s something the entire world can do. The full moon appears above the eastern horizon around the same as the Sun sets in the west. It’s a monthly one-off; the Moon rises about 50 minutes later each night, so at all other times of the month it appears either in a lightened or darkened sky. It will rise bathed in pale orange light, turning yellow as it rises higher. Start-off with your camera set to ISO 100, f/10 and 1/125sec, but the exact settings will depend upon your lens and the quickly changing light.
The best captures of a supermoon rising and/or a total lunar eclipse close to the horizon are those that have creative compositions. If you have enough ambient light to bring out the foreground, pan out a bit from the lunar disk, find something else of interest for your composition – a building, a mountain, people or preferably something unexpected – and let the majestic Moon (and perhaps also the Milky Way) help you create an out-of-this-world shot.
Jamie Carter is editor of WhenIsTheNextEclipse.com