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.
Updated 21 November 2025 In 1.3 million years’ time the star Gliese 710 is forecast to pass within 0.166 light years of the Solar System, 25 times closer than Proxima Centauri which is our current nearest star (excluding the Sun of course). The close approach of Gliese 710 will be the strongest disrupting encounter known… Continue reading Gliese 710: The Closest Future Star Encounter
With all the events going on in the world it passed almost unnoticed that a decision was made recently to abolish the leap second. The resolution was made on 18 November 2022 during a meeting held in Paris held by the International Bureau of Weights and Measures. What is a leap second? The length of… Continue reading No more leap seconds
Updated 16 December 2025 Even though the Moon is far smaller and less massive than the Earth its gravitational field still has significant effects on our planet. The most noticeable of these are tides, the periodic rise and fall of sea levels. In this post I'll give an overview of the causes of tides. This… Continue reading Overview of tides
Polaris, commonly known as the pole star, is situated near the North Celestial Pole and has been used for centuries for navigation. But Polaris hasn't always been the Pole Star and won't be in future. This is gradually changing over a 25 800 year cycle.
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