Happy Solstice, everyone. The poet in me loves that the word ‘solstice’ comes from the Latin ‘sol’ and ‘sistere’ (shout out to Patti Labelle), meaning “sun standing still.” It’s a moment in the sun’s movement across the sky when it thinks, “Nah. Imma go back the other way.”
As we celebrate this day of the year with more sunlight than any other — at least in the Northern Hemisphere — an unsung heroine waits for her moment in the shortest night. I’m talking about the real Sol Sister number one.
In 1890, Annie and Bob Hickey were appointed as caretakers of Newgrange, a monument in Ireland older than Stonehenge and the Egyptian Pyramids. They noticed that during the winter solstice, a shaft of sunlight would shine through a special roofbox above the entrance and into the main chamber onto a stone carved with a triple spiral.
Stonehenge was, and still is, aligned to sunrise on the summer solstice and sunset on the winter solstice. Chanquillo is an astronomical observatory in the Peruvian desert from around 250 BCE; thirteen towers were built so that, from the observation point, the sun rises behind the leftmost tower on the winter solstice and travels across the observatory until it rises behind the rightmost tower on the summer solstice.
I don’t wonder as much how people built these ancient observatories as why they still work. Planets wobble. 70% of Earth’s mass is a vast liquid mantle. Have you ever tried to spin a raw egg? Mars’s tilt changes over the eons; a Stonehenge built on Mars would be slightly incorrect by now. Jupiter’s axial tilt is just three degrees, so its seasons are insignificant. Uranus is leaned so far over that half the planet hasn’t seen the sun for 42 years.
Between 1969 and 1972, Apollo astronauts brought back rocks from the lunar surface so they could be studied in labs on Earth. We are still studying them today, but one of the first surprises was their similarity to rocks in the earth’s crust. Mars’s crust has twice as much iron and a distinct chemical composition. Venus’s crust seems to be primarily volcanic and basaltic, with no granitic rocks. Now that we’ve returned asteroid samples to Earth, we have found that they, too, have their own distinct compositions.
4.5 billion years ago, it’s likely that another planet about the size of Mars collided with Earth. If there had been any life here, it certainly would have been eradicated, but that cosmic disaster may be why Earth flourished ever after. The collision with that planet, now called Theia (mother of the moon goddess Selene), took a rib from the earth and formed a partner that is unique in the solar system and seems rare in the universe.
This evening, when you look up at the Strawberry Moon, a full moon that heralds a bountiful season, notice how big and round she is. She is bigger than all the dwarf planets, including Pluto. None of the planet-moon relationships we’ve seen have such a relatively large moon. That relative largeness pulls on Earth, creating tides and stabilizing our axial tilt, the perfect tilt to give us four bountiful, consistent seasons that we can count on.
In the search for extraterrestrial intelligence, there’s an idea called the Drake equation, named after the legendary Frank Drake. It’s used to estimate how many other species like us might be out there in the Milky Way. The equation starts with the rate of star formation in our galaxy, then the fraction of stars with planets, then the number of habitable planets, the fraction on which life develops, the fraction on which intelligent life evolves, the fraction of those that invent interstellar radio communication, and the average lifespan of such civilizations. The uncertainty grows with each factor.
The field of exomoons is very young. It’s hard enough to see planets around other stars. But it may be fair to say that the chances of intelligent life developing are much higher on a planet with a relatively large moon keeping it stable for billions of years, giving complex organisms like us a chance to harvest the massive amounts of energy we need to run these big brains. That might be a missing part of the equation, which would make us even more rare and special — perhaps even alone in the galaxy.
So dance around the campfire. Cherish the rarity of your perfect, imperfect partner, the only one of her kind in the universe. To all those who observe the solstice today,
aWOOOOOOOoooooooooooooo…
Your Sol brother,
Jonathan Byrd
Children
After the solstice and the apogee,
as waves of growth and fullness wash the land,
young children live forever on the sand
or in the grass, undisciplined and free.
They gain the highest cradle of a tree
to view the wide horizons they command,
knowing no more than they can understand
of peril, or of possibility.
Caught in the planet's pulse, the mighty stream
of life revolving, with resounding voice
we sing assent, dismissing as a dream
the hours of doubt, the agony of choice;
and know beyond all doubt that it is worth
the pain, to ride the wheel of death and birth.
Beautiful as a song.