This post has now been superseded by a more detailed post Measuring Distances in Cosmology ---------------------------------------------------------------------------------------------- I recently read an article on the popular astronomy website site Universe Today. It stated that ‘…the CMB [cosmic microwave background radiation] is visible at a distance of 13.8 billion light years in all directions from Earth, leading scientists… Continue reading Distances in Cosmology
Year: 2021
Advancing the Clocks
On the early hours of Sunday 14 March 2021, most of the United States will put their clocks forward an hour and Daylight Saving Time (DST) will commence. Two weeks later on 28 March most countries in Europe (including the UK) will follow, switching to summer time. In this post I’ll talk about the practice… Continue reading Advancing the Clocks
Solar Sails
Update 21 September 2025 As this is a changing area, I have replaced this post from 2021 with a revised and updated one. This is available at https://explainingscience.org/2025/09/21/solar-sails-fuel-free-space-travel/ I have also created a video which goes into solar sails in much more detail https://youtu.be/PcwASDdNQxk
Human spaceflight in 2021
2021 will be an interesting year for human space flight. Not only is it the sixtieth anniversary of Yuri Gagarin’s historic first manned spaceflight, but it will be the first time that a privately operated spacecraft will arrive at the International Space Station (ISS). This private spacecraft is not just a one-off but will be… Continue reading Human spaceflight in 2021
Explaining Science 