January 26, 2026
Gravity tea, served scalding
The mountain that weighed the Earth
A Scottish hill 'weighed' Earth — history nerds vs space-age snark
TLDR: A Scottish mountain’s tiny tug helped estimate Earth’s mass way back in 1774. The comments turned into a showdown: link-heavy historians, geophysics nerds arguing mountain “roots,” space fans asking if satellites can do better, and jokers wondering if the Sun itself got nudged.
A 1774 Scottish mountain stunt basically “weighed” the Earth, and the comments are heavier than gravity. The community split into camps fast: source-droppers like divbzero rolled in with scholarly receipts, linking Maskelyne’s notes and Hutton’s notes, while novel buffs flexed with a Pynchon cameo—helterskelter swore this whole saga shows up in Mason & Dixon.
Meanwhile, science hardcores crashed the party to explain the drama behind the drama: cossatot reminded everyone that big mountains act like icebergs with deep “roots,” which helps explain why later measurements near the Himalayas were smaller than expected. Translation: nature is messy, your plumb line (a weighted string used to find vertical) gets tugged in weird ways.
Then came the space crowd: ck2 asked if GPS satellites or the upcoming LISA (a planned space laser mission to measure tiny space ripples) could nail Earth’s mass better than the mountain method. Cue a history detour: Eratosthenes nailed Earth’s size within 2% in 240 BC, and someone dunked on Columbus for botching it by a lot.
Best meme energy? cwmoore’s deadpan: “How far does it deflect the Sun?” Peak comment section. The vibe: equal parts receipts, romance, and roasting—with gravity jokes dropping like lead.
Key Points
- •In 1774, researchers used the Scottish mountain Schiehallion to measure gravitational deflection and estimate Earth’s mass.
- •Nevil Maskelyne measured a 0.0152° difference in plumb-line direction between observatories; 0.0032° was attributed to the mountain’s gravity.
- •Charles Hutton’s surveying determined Schiehallion’s mass by mapping its shape and rock densities.
- •The team concluded Earth’s density was about 4.5 t/m³ and its mass ~4.87×10^21 metric tons, within ~20% of modern values.
- •Henry Cavendish later improved precision (1798) using a torsion pendulum to measure the attraction of lead spheres.