Science

The 24 solar terms in 2026, and why the date moves every year

A solar term is a moment, not a day: 寒露 2026 is 8 October at 14:29. Here are all 24 with their times, matching the Hong Kong Observatory's almanac to the minute — and across 1900 to 2100 not one of the 24 has a fixed date, seven take four different ones, and the published ranges have drifted since the last century.

25 Sep 2026 · 9 min read

Science

When yi (一) and bu (不) change tone, and why pinyin usually doesn't show it

一 is said yí before a fourth tone and yì before the others; 不 becomes bú only before a fourth tone; and a third tone rises before another third tone, so nǐ hǎo is said ní hǎo. Here are the rules worked through three real sentences, how often they fire in 200,000 sentences of text, and why written pinyin keeps the original tones.

23 Sep 2026 · 5 min read

Science

Finding the years your lunar and solar birthdays fall on the same day

Your lunar birthday and your solar birthday meet only a few times in a lifetime. The first match is at 19 for 57% of people, and at 11, 38 or 46 for the rest. Here is how to find your own matching years, and what happens if you were born on a 30th or in a leap month.

22 Sep 2026 · 5 min read

Science

How many ancestors did you have a thousand years ago?

Doubling every generation gives you about a trillion ancestors a thousand years back, more people than have ever lived. Here is where that arithmetic breaks, a simulation of how fast real ancestor counts level off, and when everyone's family trees meet.

21 Sep 2026 · 7 min read

Science

Two published rules for the new moon disagree about one month in three

MABIMS and Muhammadiyah's wujudul hilal are both published and computable a year ahead. Worked through fourteen lunations from October 2026, they give a different start date on five, always one day apart, and identically in Kuala Lumpur and Jakarta.

21 Sep 2026 · 7 min read

Science

A4 is the answer to an equation, and US Letter is not the answer to anything

Two constraints — a ratio of √2 and an area of one square metre — have exactly one solution, and that solution is A0. The 141% button on every photocopier is that ratio. US Letter's origin story traces to a page filed under "fun facts", which its own trade association now calls folklore.

20 Sep 2026 · 10 min read

Science

A Nitrogen-Fixing Enzyme That Only Works Near the Boiling Point

It comes from an archaeon at deep-sea volcanic vents, it is the simplest structure of its kind yet imaged, and it does nothing when cool.

20 Sep 2026 · 5 min read

Science

Disorder Can Stabilise a Network. Identical Parts Can Break It.

Variation helps a grid, a swarm or a food web, but only when the individual units have enough behaviour of their own.

20 Sep 2026 · 5 min read

Science

The octane numbers on American and Asian pumps are not the same scale

American 87 is roughly 91 RON, because the United States posts the average of two laboratory tests while most of the world posts one of them. The same ASTM methods are used everywhere — only the published number differs, and every US pump says so in small print.

19 Sep 2026 · 7 min read

Science

Roman Space Telescope Now Carries Fuel for 22 Years of a 10-Year Mission

A course correction cost a tenth of its propellant budget. What that buys is optionality, not an approved two decades of observing.

19 Sep 2026 · 5 min read