Can you feel it? Did you mark its approach? Can you sense our passage across its threshold?
Something has changed for us. Something new and remarkable has happened. We have entered the age of planets and, even if you can't see it now, nothing will ever be the same.
Yesterday scientists announced the discovery of Kepler-22b. It's an Earth-sized planet orbiting a star very much like the sun. The newly discovered world sits right in the middle of the star's "habitable zone" where surface water can exist in liquid form. From a distance, Kepler-22b appears to be a goldilocks world, orbiting a goldilocks star, in the goldilocks zone. In theory, at least, everything appears just right.
This discovery comes on the heels of other announcements about other planets with good "fitness" for life (though with lesser degrees of this all-important quality). You can expect more discoveries like these. With new tools in orbit and on the ground, scientists have begun a census of planets in our galaxy. Their discoveries represent one front in a revolution that is already reshaping humanities vision of itself and its place in the Universe.
The age of planets has begun.
An ancient question is being answered here. Since the time of the Hellenistic Greeks human beings have asked if other planets might exist around other stars. The possibility of life on those other worlds always hovered just beyond that first question. Now, in our own era, we have definitely answered the question of "other planets" (we can expect billions of them in our galaxy alone). The second question — life on the other worlds — remains unanswered.
But something remarkable happened on the way to dealing with both questions. Just as we were developing tools to search for worlds beyond our sun — so-called exoplanets — the understanding of our own world took a dramatic turn. The new age of planets came to include our own.
It is no accident that discussions of climate change, the biosphere and sustainability arose alongside our explorations of habitable exoplanets. Over the last half-century similar tools and similar science have led us to a broad and remarkable new understanding of our own world. From the movement of continents to the movement of ice-age glaciers, from the oxygenation of the atmosphere by early bacteria to a changing atmosphere driven by human activity, we have developed a new and highly sophisticated understanding of how Earth and its life evolve together.
This vision of our planet as a complex web of systems (including life) did not exist 50 years ago. It does now and, like it or not, it will inform everything we do in the future. If we are smart enough and lucky enough to develop a sustainable global civilization it will be through the perspective gained by this new science.
As we play out the drama of Eurozones, Great Recessions and 2012 elections, something far more powerful is happening under our feet. The news of the day will come and go and most of it will be forgotten by the time the Earth completes another turn around the Sun. But our entry into the age of planets will not be forgotten.
Should we make it for another 1,000 years, if there is anyone left to remember, then this threshold we are crossing now will be remembered as one of the great moments in our evolution. More to the point, if there is anyone around to remember our crossing into this age of planets, it will be because we were here to make that step.
You can keep up with more of what Adam Frank is thinking on Facebook and Twitter. His new book is About Time: Cosmology and Culture at the Twilight of the Big Bang.