The Solar Eclipse: When the Moon Gets in the Way

Here in Mallorca, the eclipse has already managed to alter daily life several hours before doing anything to the Sun.

Roads are closed, traffic has been redirected and restaurants here in Playa de Palma that had expected one of the busiest evenings of the year are, somewhat impressively, standing empty.

Apparently even celestial mechanics requires traffic management.

Still, I am looking forward to tonight.

We know exactly what is going to happen. There is no mystery about the astronomy. The movements of the Earth, Moon and Sun can be calculated with extraordinary precision.

What interests me more is why something so predictable can still fascinate us so much.

Part of the answer may lie in how the nervous system deals with the expected.

Most of what surrounds us barely reaches conscious attention. Daylight changes gradually. Shadows behave themselves. The horizon stays where we left it. The retina converts light into neural signals, while the brain uses those signals to construct a remarkably stable experience of the world.

Then the Moon gets in the way.

Suddenly the light is wrong for the time of day. Familiar colours and shadows look unfamiliar. What reaches the brain no longer quite matches what experience has taught it to expect.

And discrepancies get our attention.

Neurology is full of reminders that perception is not simply a recording of the outside world. Migraine can make ordinary light intolerable. Neuropathic pain can create burning where there is no heat. Vertigo can create movement in a motionless room.

The experience is real, even when it does not correspond neatly to the physical stimulus.

An eclipse is obviously something very different, but it exposes the same fundamental fact: there is always a nervous system between the world and our experience of it.

But I suspect there is another reason eclipses affect us so strongly.

Most of us spend our days inside fairly convincing small worlds: patients, children, messages, invoices, deadlines, traffic, dinner. The human brain is remarkably talented at making whatever is directly in front of us feel like the centre of existence.

Tonight, for a few minutes, the scale changes.

The Moon passes between us and a star. Daylight disappears. And suddenly it becomes difficult to forget that we are standing on a rotating planet, moving through space according to physical laws that have been operating perfectly well without our involvement for several billion years.

There is something oddly clarifying about that shift in scale. Our usual priorities are still there, but they are placed in a much larger context.

Nothing has changed, and yet our sense of proportion may have.

Tonight I intend to look up.