Celebrating Solstice and Learning Something New.
Yesterday, as many of you are most likely already aware, the Sun, the Moon and the Earth come into alignment. They do this on a regular basis, but on June 21, 2020, this happening was made all the more special for all sorts of reasons.
Firstly, this alignment produced a rare event with an annular solar eclipse taking place on the same day as the June solstice – the summer solstice in the Northern Hemisphere and the winter solstice in the Southern Hemisphere.
This coincidence of an annular eclipse on the same day of the June solstice will only take place on one other occasion this century (in 2039), so – in my books – that made this eclipse a rare occurrence indeed.
Next, there was more than just this lucky coincidence of nature because several other events had to occur as well.
Annular eclipses can only take place during the Moon’s new phase when the New Moon is at, or very close to, a lunar node*, allowing the Sun, the Moon, and the Earth to align in a straight line or one that is almost straight, and the Moon must also be near apogee, its farthest point from the Earth. (Phew!)
Finally, all of these conditions have to happen at the same time for the apparent size of the Moon to be (or appear) almost the same as the apparent size of the Sun because, during an annular solar eclipse, the Moon only covers the Sun’s centre, leaving a ring of fire or ‘annulus’ visible around the Moon.
It feels like a big ask, but the universe is amazing and all of those events transpired yesterday, and while they did, I sat in the comfort of my own home and watch the spectacle unfold online via TimeandDate.com.
The ring of fire only lasted for a short period of time but it was incredible. One day I hope to witness a ring of fire in person.
Here’s a screenshot I took while enjoying the show.
– ⋅ o ♥ o ⋅ –
And here’s what I learnt yesterday:
For this to happen, allowing us to witness that amazing ring of fire, the length of the umbra part of the Moon’s shadow must be shorter than the distance between the Moon and the Earth. Yesterday, I learnt the Moon was approx. 390,000 km (242,334.765 miles) away from the Earth, and the length of the umbra shadow was approx. 370,000 km (229,907.341miles).
This discrepancy creates an antumbra: a lighter area of a shadow that appears beyond the umbra, at a certain distance from the object casting the shadow. It only exists if the light source has a larger diameter than the object and from within the antumbra, you will see the outer rim of the light source around the object casting the shadow.
A solar eclipse is only referred to as an annular solar eclipse when the Moon’s shadow casts/creates this antumbra allowing you to see the edge of the Sun like a ring of fire around the Moon. (If you are standing in the right place at the right time, of course.)
Isn’t it amazing that the Moon, with a diameter of approx. 3,474 km (2,159 miles) and 400 times smaller than the Sun (diameter of approx. 1,391,000 km or 864,327.33 miles), appears to almost completely cover the Sun during an annular solar eclipse?
Isn’t it equally as amazing that the Moon covers the entire Sun’s surface during a total solar eclipse?
There will be another annular eclipse on June 10, 2021.
* I find it hard to define what a lunar node is, so here’s an explanation I found online:
The Moon’s nodes are not physical planetary bodies but the points of intersection between the Sun’s apparent orbital path around the Earth, the ecliptic, and the Moon’s orbital path around the Earth.