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One thing I learned pretty quickly was that astronomers don’t only use a lot of weird units (like milliCrabs for example – more on this in another post) but they also use a lot of terms that don’t mean much at first hearing by the unenlightened. One such is ‘gravitational radius’… someone may say that something is ‘three gravitational radii from” an object. Continue reading “TIDK #2 – My gravitational radius”
This really is a brilliant time to be an X-ray astronomer. Launched on 13th July 2019 on board the SRG spacecraft, the eROSITA X-ray telescope has completed its first full sweep of the sky, mapping more than a million energetic objects and so roughly doubling the number of known X-ray sources discovered since the dawn of X-ray astronomy some 60 years ago. Continue reading “eROSITA’s new X-ray map of the Universe”
TIDK = Things I Didn’t Know… until I started gathering the knowledge that in another lifetime may have made me a professional astronomer. This may become a long list…
I knew that neutron stars were stellar remnants, leftovers of stars that had finished with nuclear fusion and collapsed under their own gravity to the point where protons and electrons were crushed together to create more neutrons to join those that were there already. So my answer would have been “neutrons” whether you had asked me “what’s the surface made of?” or “what’s the centre made of?”. Neutrons all the way down and through. Continue reading “TIDK #1 – Neutron star interiors”
Years ago, we had a wooden nest box that was used regularly by the blue tits in our garden but it eventually proved itself not to be woodpecker-proof. On seeing a woodpecker industriously enlarging the hole in the front of the box we had to make emergency repairs with gaffer tape, which also deterred the woodpecker so the tits could fledge. We replaced the damaged wooden box with a woodcrete one, and the blue tits came back every year until three years ago when we noticed that nuthatches had moved in. Continue reading “Nuthatch protection”
For the detail behind the content of this post see “Neutron Star Radius-to-Mass Ratio from Partial Accretion Disc Occultation as Measured through Fe Kα Line Profiles” as submitted to ApJ by Riccardo La Placa et al, March 2020. Continue reading “Prospective method of measuring neutron star radius/mass ratios”
If you have an institutional sign-in to Springer Nature then you have the opportunity to download free soft copies of hundreds of text books. Springer Nature has taken this admirable initiative in support of worldwide learning and teaching institutions which are currently closed because of the Corona virus pandemic.
What a bizarre idea. Or is it? Many years ago, when I was walking to school, any friend passing by on a motorcycle or scooter could offer me a lift, and I would just hop on without a care. Then we had compulsory helmet-wearing, despite the best efforts of the then newly-formed Motorcycle Action Group. Now the busybodies are trying again to get helmet-wearing made compulsory for cyclists. I thought it odd that the notion of helmets for car occupants never, ever, gets a mention so I consulted Dr Google to find out if being in a car makes you invulnerable to head injuries. Continue reading “Helmets for car occupants?”
Before committing to becoming a post-grad researcher in my old age, I tried a Stanford University MOOC course in Special Relativity just to see what I was letting myself in for. MOOCs (massive open on-line courses) from some of the world’s top universities are freely available, but they’re not the only internet resources for lifelong learning and re-skilling. Link
Ever wondered what title you have to the space above and below your property? The laws in the UK and the US were founded on the principle of Cuius est solum, eius est usque ad coelum et ad inferos (whoever owns the soil holds title up to the heavens and down to the depths of hell). Modern day pressures are changing all that… Link
Fewer than one in five British people think BBC Radio 4’s Thought for the Day should always feature religious content (survey by Censuswide). BBC policy is to explicitly exclude non-religious voices. Please read on, and then consider signing a petition to get this changed. Link Continue reading “National Secular Society Petitions the BBC”