The ‘Ring of Fire’ solar eclipse and summer solstice are on the same day for the first time 19 years — and they’re only going to get rarer

• On June 21, the summer solstice and the ‘Ring of Fire’ solar eclipse will occur on the same day.
  
• The last time this happened was in 2001, 19 years ago. In the current lunar cycle, we’re lucky that we shall see 5 solstice solar eclipses in a row.
  
• Once it resets, there won’t be another solstice summer eclipse for nearly 200 years.

For the first time in 19 years, the ‘Ring of Fire’ solar eclipse and the longest day of summer — the summer solstice — are set to happen at the within the same 24 hours. The rare phenomenon is called a ‘solstice summer eclipse’, and it’s only going to get rarer.


The last time this happened was on 21 June 2001. And even then, it was during the total solar eclipse — not an annular solar eclipse which yields the ‘Ring of Fire’.

Before that, there was a solar eclipse during the summer solstice of 1982 — and the next is expected to happen on 21 June 2039, with another one in 2058. But after that, a solstice summer eclipse won’t happen for nearly 200 years.



The odds of a solstice summer eclipse
Solstices occur twice a year — once in each hemisphere. For there to be a solar eclipse, there has to a new moon in the sky, which happens once every 29.53 days. There’s a 3.4% chance that both of those events will occur together.

However, for solstice summer eclipse you don’t just need a new moon — you need for the Moon to be in perfect alignment between the Earth and the Sun.

For all of the 1900s — the 20th century — there were a lot of 1,237 new moons. However, only 228 of them occurred during a solar eclipse, a mere 18% of all new moons.

This means, on average, the odds of a solar eclipse and the solstice occurring on the day are only once every 82 years.

So why are we seeing a solstice solar eclipse in only a gap of 19 years?
The reason for the discrepancy is the cyclical nature of the universe. The phenomenon of 19-year eclipse cycle is called the ‘Metonic cycle’.

For every 19 years that go by, almost 235 lunar months come to pass as well. The keyword being ‘almost’. The 235 lunar months fall short by 72 minutes. When they add up, they push the Earth out of sync with the solstice and the cycle needs to start over.

We just happen to be living at a time which is smack in the middle of a lunar cycle that coincides with our annual calendar.

If you look before 1982, the last solstice summer eclipse occurred on 22 December 1870 — a gap of more than a century. An entire generation lived and died without ever seeing a solstice summer eclipse.

The same holds true if you jump forward in the future. After the solstice summer eclipse of 2058, another won’t occur till 22 December 2242 — that’s a gap of almost 200 years.

So we are fortunate enough to see so many solstice summer eclipses in our time, but there’s a long drought coming after that. Once 2058 comes and goes, the solstice summer eclipse won’t be nearly two centuries.

SEE ALSO:
Summer Solstice — Here’s why June 21 is going to be the longest day of the year in India

‘Ring of fire’ solar eclipse images from the last 10 years that will inspire for what’s to come tomorrow

Solar eclipses in 2020 — twice a year that the Moon will try to block out the Sun