These are some of my cosmology posts
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Congratulations Blue Origin!
A week is certainly a long time in crewed spaceflight! Following Richard Branson’s trip to “the edge of space” on Sunday 11 July, Jeff Bezos went one step further on July 20. He made a short journey to space, in the first crewed flight of his Blue Origin rocket ship, New Shepard. As the spacecraft…
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Congratulations Virgin Galactic
Great news from Virgin Galactic on Sunday. Although according to the widely used definition, their spacecraft didn’t quite get into space. Most international authorities define that space begins at an altitude of 100 km (the Karman line), whereas VSS Unity reached an altitude of 86 km, but a fantastic achievement nevertheless !!. For those who…
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The Space Shuttle 10 years on
Ten years ago, on 8 July 2011 Atlantis took off for the final mission of a Space Shuttle, bringing to close a programme which had lasted nearly 40 years and had cost the equivalent of $220 billion in 2021 dollars. In this post I’ll review this fascinating and unique piece of technology. The landing of…
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June 21 2021 – the solstice
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. The origin of the word solstice is from two Latin words: sol, which means Sun, and sistere, to stand still. On the…
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Satellite Navigation
Satellite navigation systems have come to affect countless aspects of our daily lives, from directing our holiday aeroplanes to enabling us to drive round an unfamiliar city without any map other than the one on our mobile phone. Most new cars sold today have an inbuilt Sat Nav and you can buy trackers relatively cheaply…
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The Observable Universe and Its Horizons
Updated March 2026 Although the Universe may be infinite in extent, in the generally accepted Big Bang cosmology we are only able to see a small fraction of it. We call this small fraction we can see the observable universe. Outside the boundary of the observable universe lies a much larger region the unobservable universe…
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Easter April 4 2021
This year, for the majority of the world’s Christians, 4 April is Easter Sunday, one of the most important dates in the calendar. Although because of the current restrictions due to the Covid pandemic, celebrations will be a little limited in many places. Although Easter is the festival celebrating the resurrection of Jesus Christ from the dead,…
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Distances in Cosmology
Discusses the nuances of distance measurement in cosmology., focusing on the cosmic microwave background (CMB) and its proper distance of 46 billion light years from Earth. It clarifies concepts such as light travel distance, proper distance, comoving distance, and various astronomical distance metrics, emphasizing the expansion of the Universe… Continue reading Distances in Cosmology →
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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…
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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
Explaining Science 