The Moon is going to put on a spectacular show this week and stargazers around the World are getting ready to observe the May 26th Super Flower Moon, blood Moon and lunar eclipse. But what are all these events? Why do they happen? And, most importantly …will YOU be able to see them? Let’s get our facts straight!
Eclipses, occultations, transits…which is which?
Astronomers use several terms to describe a passage of one celestial body in front of the other as seen from Earth.
They call it an eclipse when the Moon passes in front of the Sun (Solar Eclipse) or the Moon disappears into the Earth’s shadow (Lunar Eclipse). Another term, occultation, describes a passage of a larger body in front of a smaller one, for example when the Moon (lunar occultation), planets (planetary occultation) and asteroids (asteroid occultation) pass in front of individual stars or other planets. During an occultation the background body gets completely covered by the one passing in front.
Finally, a transit is yet another word we use to describe the passage of a smaller body in front of a larger one – such as an exoplanet in front of its parent star or the inner planets (Mercury and Venus) in front of the Sun. In that case the foreground body is usually the one we are interested in.
Eclipses, occultations and transits are all similar events in a sense that they are possible simply because of a peculiar geometry, an alignment of celestial bodies along our line of sight. But they are not only beautiful to observe, but also very important for scientists. They allow us to use various clever techniques to obtain new data that otherwise would have been unavailable. It is no surprise then that some people become eclipse chasers and travel the world to catch and record these unique astronomical events.
The whats, hows and whens of lunar eclipses
When the Sun, the Earth and the Moon align and the Earth’s shadow falls on the Moon, a spectacular event called a lunar eclipse occurs. Naturally, this alignment is only possible during the Full Moon phase, although lunar eclipses do not happen every Full Moon. The reason is the 5 degree tilt of the plane of the Moon’s orbit in respect to the Earth’s orbital plane. As a result of this misalignment, the Moon sometimes passes above or below the Earth’s shadow (in that case no eclipse occurs) or only grazes the Earth’s inner shadow (in that case a partial lunar eclipse occurs), or even passes only through the Earth’s outer shadow (in that case a penumbral lunar eclipse occurs). As a rule, we can observe a total lunar eclipse from any given point on Earth approximately once every 2.5 years.
May 26th Full Moon
This month the Moon will reach its Full Phase on May 26th at 12:13 pm BST. Just like other Full Moons of the year, the May Full Moon has a traditional name, Flower Moon, because this is the time when flowers begin to bloom in many parts of the World.
The 2021 May Full Moon is also a Supermoon. ‘Super’ here refers to the Moon being near its closest point to the Earth and therefore looking a bigger and brighter than usual.
Fun fact: a New Moon can also be a Supermoon, though new supermoons don’t usually get much attention as, by definition, they are not visible from Earth.
May 26th total lunar eclipse
The May 26th Full Moon will be aligned with the Sun and the Earth so that the total lunar eclipse will occur. But whether or not you will be able to see the event depends on where you live. The observers in New Zealand, Australia, Japan, the US (Hawaii, Alaska and Western coast) and Western South America will be able to enjoy the total eclipse in full. Stargazers in some other parts of the World will only see a part of the eclipse (check the detailed map of the May 26th lunar eclipse). Sadly, the May lunar eclipse will not be visible from the UK. But, thanks to modern technology we can still take part in the eclipse-gazing virtually!
The May 26th eclipse will last 5 hours and 2 minutes, of which the full eclipse will last 14 minutes. The totality will occur at 12: 11 pm BST (7:11 am EDT).
What’s with the Blood Moon? Will the Moon really turn red during the upcoming lunar eclipse?
During a total lunar eclipse the Moon does not disappear from the sky completely. It turns dark and, often, copper red. That’s why we call total lunar eclipses Blood Moons. This ‘bloody’ appearance has to do with the Earth’s atmosphere! You see, while the rocky body of the Earth does block the sunlight, the light still passes through the gaseous envelope surrounding the Earth, our air. There it gets separated into different colours with shorter waves (i.e. blue) being filtered out and longer ones (i.e. red) passing through. It is this remaining light that illuminates the Moon and paints it red!
Fun fact: the fully eclipsed Moon can also sport other colours, such as brown or yellow, depending on the condition of the Earth’s atmosphere!
Check out our May 2021 Stargazer’s calendar to find out what’s up in the sky this month. If you are a beginner stargazer, the following Open source planetarium software and free night sky apps for stargazers might help you navigate the night sky. Alternatively, you can visit our Portable Planetarium and embark on a journey of the virtual heavens with one of our knowledgeable Star Dome presenters. We hope to see you on one of our shows!