The post clarifies the distinction between a planet's rotation period and its day length, emphasizing that for planets like Venus and Mercury, these can differ significantly. It explains the calculation of a day length and examines prograde and retrograde rotation, revealing misconceptions found in popular science.
The post explains that a year is defined by Earth's orbital motion around the Sun, encompassing three types: the sidereal year (365.256 days), the tropical year (approximately 365.242 days), and the anomalistic year (365.259 days). It discusses their lengths, differences, and the implications for calendars, notably the transition from the Julian to the Gregorian calendar to align with seasonal changes.
Explores perfect numbers, defined as positive integers equal to the sum of their proper divisors. Examples include 6, 28, and 496, with only 52 known today. It discusses mathematical properties, unsolved questions about odd perfect numbers, historical significance, and the connection to Mersenne primes, highlighting their allure across centuries.
The author shares a curated list of five recommended science books, emphasizing that they are well-reviewed and written by experts in their fields. The selection includes titles from prominent scientists including Neil Degrasse Tyson and David Deutsch, targeting a general audience interested in science.
Updated 30 November 2025 A lot has happened since I wrote a  post back in June 2025 about the Artemis programme. At the time it looked like America would be landing astronauts on the Moon in mid-2027. However in October, concerned by delays in SpaceX’s Starship HLS, the NASA Acting Administrator Sean Duffy revealed that… Continue reading NASA’s Artemis Moon Missions Update
Explaining Science 