The Earth receives more energy from the Sun in a single hour than the whole of humanity consumes in an entire year. In this post I’ll talk about some of the science behind this interesting fact and I’ll also discuss how solar energy is likely to become more important to us in the future. How… Continue reading Solar energy
Not many people know this, but next Tuesday 18 September, is the shortest solar day of the year. I’ve decided to re-blog my post from 2015 on this interesting fact.
Revised 10 September 2018
Most people are probably unaware of this but the length of a solar day, which is the natural day measured by the rising and setting of the Sun isn’t always 24 hours. It varies slightly throughout the course of the year and that September 18 is in fact the shortest solar day in the year. This post discusses this curiosity, which is not widely known.
Background- the variation in the length of the day.
Although a day for practical timekeeping purposes is always 24 hours, the actual length of a solar day, which is the time difference between two successive occasions when the Sun is at its highest in the sky, varies throughout the year. As shown in the graph below, it is at its longest, 24 hours 30 seconds, around Christmas Day and is at its shortest, 23 hours 59 minutes 38 seconds, in mid-September.
How the length of a solar…
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This year, the June solstice will fall on 21 June. In the northern hemisphere, it is the day when there is the most daylight and when the Sun is at its highest in the midday sky. Sunrise at the solstice at Stonehenge, England - image from Wikimedia commons The origin of the word solstice is… Continue reading June 21 2018 – the solstice
On May 9 the planet Jupiter will be what is known as 'at opposition'. This event, which occurs every 399 days, happens when Jupiter is at its closest to the Earth and at its brightest. To the naked eye it will be a brilliant white object, three times brighter than the brightest star. Features such… Continue reading Jupiter at opposition 9 May 2018
As discussed in my previous post, Kepler's improvement of Copernicus's heliocentric system led to its more general acceptance, and his three laws describing the way planets move are fundamental laws of astronomy. However, this wasn't his only contribution to science. He was one of the greatest thinkers of the seventeenth century scientific revolution and in… Continue reading Kepler’s other achievements