Whenever supermoons and eclipses make the news, people’s interest in the night sky soars.
Big and bright in all its visible phases, the Moon (Earth’s closest neighbour in space) is difficult to miss, even in the daytime.
Late last month, many will have noticed our Moon appeared bigger and brighter than usual. On 27th April, its waxing gibbous orb culminated in a lovely super full Moon, which rose in the east just after sunset. Spectacular for a couple of days before and after sundown, it also appeared beautiful for early risers as it sank to the west in the early hours.
This was the first of two super full Moons in 2021. If you missed it, the good news is we won’t have to wait long for the next one, which also comes with a twist!
Mark the evening of Wednesday 26th May in your calendars, not just for the next supermoon but also for a total lunar eclipse.
What makes a supermoon super?
The supermoon phenomenon that people notice occurs when a full Moon phase coincides with the Moon’s closest approach to Earth. The Moon’s orbit around Earth is an ellipse, not a circle, so its distance from Earth can vary from a 406,000km at the furthest point of the ellipse (the apogee) to 357,000km at the closest (the perigee). A supermoon that happens at perigee, will appear 14% bigger and 30% brighter than its opposite, a micromoon. Only some supermoons get properly noticed since those that occur around the new Moon phase are virtually invisible, and the crescent phases are not as noticeable.
Supermoon (perigee) and micromoon (apogee) (timeanddate.com)
And the total lunar eclipse?
The second celestial event for 26th May is a total lunar eclipse, also known as a ‘blood moon’. This happens when the full Moon, Earth, and the Sun line up. This alignment term is delightfully called a ‘syzygy,’ from a Greek word meaning ‘being paired together’.
The Moon does not create its own light but instead is illuminated due to its surface reflecting the Sun’s rays. During a total lunar eclipse, Earth blocks direct sunlight from reaching the Moon. From the Moon’s perspective, the Sun is behind Earth, resulting in the Earth’s shadow falling on the Moon instead of the Sun’s rays.
The total lunar eclipse starts once the moon is completely inside the umbra. And the moment of greatest eclipse happens with the Moon is halfway through the umbra as shown in this graphic (NASA)
Exactly where and when will we see the eclipse?
Conditions permitting, night owls will be treated to the entire eclipse from beginning to end. The eclipse will last five hours, beginning at 8:47pm on the 26th and concluding at 1:49am on the 27th. However, the period of totality will be very brief, lasting only 14 minutes from 11.11pm to 11.25pm. We might call this a ‘shallow’ total eclipse since the Moon will only just make it into Earth’s umbral shadow.
Since it will be occurring late in the evening, the Moon will be high in the sky throughout, and therefore is less likely to be obstructed by cloud (emphasis on ‘less’ likely)!
It won’t matter where you are in New Zealand – as long as the clouds stay away, you will see this eclipse.
Stages and times of the lunar eclipse. All times are local time (NZST) for Auckland (timeanddate.com)
Where does the term ‘blood moon’ come from?
It’s all to do with light and the atmosphere. The sky is blue because as the Sun’s light hits our atmosphere, more blue light is scattered across the sky than the other colours. Red light is often seen during sunset because we view it through the thicker parts of Earth’s atmosphere, and being of a longer wavelength, more red light gets through. When the Moon goes into Earth’s shadow, the reddish light passing through Earth’s atmosphere around the limb of Earth refracts onto the Moon, creating a blood-red colour across the lunar surface.
Unlike solar eclipses, lunar eclipses are completely fine to view with the naked eye.
Looking forward to November 2021
If the weather is not cooperative for the May event, or even if it is, we suggest you mark 19th November in your calendars as well. Although this will be a partial eclipse, it will be close to total and will reach its maximum earlier in the evening than the May event. It has the potential to be quite pretty as it will be sitting just above the beautiful Matariki star cluster.