This explains the stages of twilight , and describes how the Sun's path changes throughout the year in Manchester, England. The phenomenon of "Simmer Dim" in the Shetland Islands is highlighted, characterized by continuous twilight and celebrated with a festival.
Author: Steve Hurley
Hi I am Steve Hurley. Although I work in the IT industry. I studied for a PhD in astronomy in the 1980s. My real passion is explaining scientific concepts to a non-scientific audience. My blog (explainingscience.org) covers various scientific topics, but primarily astronomy. It is written in a style that it is easily understandable to the non scientist.
Publications and videos
For links to my books and videos please visit www.explainingscience.org
e-book from Explaining Science on Venus
Updated 7 December 2025 I have now updated my e-book on Venus, the planet closest to the Earth in distance, size and internal composition, and the third brightest natural object in our sky after the Sun and the Moon. Topics include how Venus appears from Earth and the fact that Venus’s phases can only be… Continue reading e-book from Explaining Science on Venus
The Impact of Stellar Aberration on Astronomy
Stellar aberration was discovered by James Bradley in 1727. He observed unexpected star position shifts, confirming the heliocentric theory and enabling light speed measurement. Today, it's explained by Einstein's theory of relativity.
Solar energy costs
In a previous post I talked about the advantages of solar electricity compared to other renewable source of electricity. In this post I’ll move away from my normal scientific topics and discuss the costs of small scale solar energy and how it compares with other renewables. Whats is 'the LCOE'? When comparing the relative costs… Continue reading Solar energy costs
Advantages of solar energy
As shown in the graph and table below, most renewable electricity is generated by hydroelectric power. Solar energy lies in third place behind wind. Electricity generated from renewable sources. From Our world in data (2018). The ‘Others’ category includes biofuels (e.g. burning wood, animal and agricultural wastes), geothermal energy and wave/tidal power) Despite only being… Continue reading Advantages of solar energy
