Riding — and reading — the Earth tide

Once a day, Miaki Ishii rides the Earth tide, rising slowly — along with her desk, chair, and entire office — 20 to 30 centimeters before sinking back again.

Ishii isn’t alone on her little journey. She makes it with the rest of us, together with our desks and chairs, houses and office buildings, rising in concert as the solid earth responds to the tug of the moon and the sun.

The Earth tide is a little-known daily event, similar to the oceans’ more familiar tides. But the sun and moon’s gravity doesn’t just pull on water, it deforms the Earth itself, causing the ground beneath us to bulge toward the pulling heavenly body.

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