The sun spews huge masses of atomic particles in loops and flares and flashes a million miles above its seething four-million-degree (F) surface into a stellar corona. And the sun shoots immense volumes of cosmic rays and subatomic particles at nearly the speed of light, a solar wind that picks apart human DNA when given the change.  But the earth’s molten iron-and-nickel core sloshes spherically around inside, generating a massive magnetic field that deflects most of the solar wind.  What this all means, Dad explained to Cecilia, is that we can live, here, safely on earth.  “Without the magnetic field….”  His cosmology lesson came from volume “C” of the encyclopedia: corona; core; cosmology: this morning’s reading.  Cecilia reminded Dad about his shower, and his breakfast of a whole wheat English muffin and two slices of pre-cooked bacon and a tall glass of cold milk (and 19 pills).  The chair lift shook and boomed at the bottom of the stairs, and I worried he or Mom would tumble onto the tile.  Accessible Systems came the next morning to repair it, under warranty, so now I need not worry, as much.  “Do you think we might cut the grass today?” Dad asked me after work, and I felt sad that he felt he needed my permission, though certainly he needed my help.  6:00 p.m.  I reminded him about how frightening and difficult it was for him to mount the mower last time, but could not say “no.”  Don’t rob him of what little he has left, I thought.  But this time we managed impressive transfers to and from the mower, and he motored around the yard, sun hat askew, all the jogging neighbors waiving and smiling their astonishment.  Pull weeds and trim bushes.  7:00 p.m.  Cook dinner and serve.  8:00 p.m.  Clean up kitchen.  9:00.  Listen to thoughts and stories.  10:00 p.m.  I am just too tired to read or to pray or to clean my teeth (though I do the latter anyway).  No time for TV, for 6:00 a.m. comes early, and I am too old to go without sleep.  And I self-assess: Why am I so irritable?  Mom thinks of me wistfully as her little boy, her first baby pulling pots out of cupboards and crawling, cloth-diapered, across the floor, smiling and untroubled.  When, troubled, I say good-night: “I will miss you.”  When, troubled, I arrive at home: “I’m so glad you’re back.”  But I am almost 60, too prickly, less cuddly and cute.  It would be better for them if I visited here rather than lived here: the visits would be more joyful and less chore-full.  But they need me, and a visiting life cannot be the agenda.  As I said good-night, I wondered aloud to Dad: How is it that the moon is just the right shape and size and distance and orbit to just block out the sun and reveal its beautiful chaotic million-mile hot hot corona?  And he shrugged with like wonder.