On the immensity of space

The Total Solar Eclipse of August 21, 2017 - fly along with the shadow! from Eclipse2017.org on Vimeo.

(A version of this post appeared on the Vatican Observatory Foundation's Catholic Astronomer blog.)

Not quite two months ago I spent a late morning and early afternoon watching the moon slide across the sun, turning midday Philadelphia into twilight and back again.  I stashed the eclipse filters for the occasional look at the sun, and dove into the semester.  But each time I head out for a late evening walk and see the full moon hovering over the neighborhood school's field, I think about it coming between the earth and the sun.

I tend to think of the moon and sun as large objects ponderously processing through space, from my perspective taking ten or a dozen hours to creak 'round the sky. Their movements marking out days, months and years, not so much minutes and seconds.  So I was struck on the animations of the eclipse by how fast the moon's shadow moved across the ground, even when you account for the speeded up motion  (in this video slightly more than a factor of about 13).  With family in California, I've flown coast to coast more time than I can count.  It takes me 5 to 6 hours to fly from here to there, soaring through the sky at three-quarters the speed of sound.  The umbra — the shadow —  took only 90 minutes to make the same trip, traveling at more than 1200 mph.

As I walked yesterday afternoon, watching the sun vanish behind the horizon as my spot on the earth rotated to face away from the sun, it occurred to me that the moon's shadow isn't the only thing moving fast.  When standing "still" on earth I am, of course,  in motion relative to other points in the universe. Points on the surface of the earth (at my latitude 40^oN) are moving at 750 mph. Fast indeed, but not so fast I cannot imagine it.

In this moment in history, where I can climb on a plane and be on the other side of the world in half a day, or video chat with my kids who are thousands of miles away or I can go to a lab downstairs and with a quantum mechanical trick, nudge atoms around, arranging them to suit me, I might be tempted to think of myself as commanding great powers. At least until I think about how fast the earth is moving around the sun.  67,000 mph hour.  The solar system?  Orbiting the galactic center at a half million miles per hour.  I am moving through space at speed I cannot truly fathom: a thousand feet flash by in a millisecond, a hundred thousand in a second.  Eighty thousand miles in a minute.

Lines from Psalm 29 from Lauds, Week I, came to mind:

The Lord's voice resounding on the waters,
The Lord on the immensity of waters;
The voice of the Lord, full of power,
The voice of the Lord, full of splendor.

The Lord on the immensity of waters, the Lord on the immensity of space.  Adore the Lord in his holy court.

The psalm ends with an assurance that God, whose strength we cannot fathom, who with a word can strip the forests bare, and spin a universe into being, will grant us peace.  I can think of nothing else we need more now than this. Peace and God's unimaginable strength to sustain and protect us on this tiny world hurtling through space.