Author Archives: Allen Versfeld

About Allen Versfeld

Allen is an amateur astronomer, an IT professional, a podcaster, a father of five growing kids, a barely competent chess player, and the owner and publisher of the Urban Astronomer podcast and website. He has formerly served as Director of the Astrophotography and Citizen Science sections of the Astronomical Society of South Africa. You can find his personal social media feed on Mastodon!

Messenger: 15 days till orbit

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In 15 days time, Mercury will gain a new satellite in the form of the MESSENGER spacecraft.  Launched in August 2004, Messenger has been tracing a complex journey through the inner Solar System which will end on 18 March 2011 when it is inserted into an elliptical polar orbit around the planet Mercury.  MESSENGER’s mission is to study and map Mercury, giving detailed information on its magnetic field and the mineral composition of its surface. MESSENGER will have an unusually … Continue reading →

Spacecraft orbits Mercury

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At 01h00 UTC this morning, MESSENGER ended its six and a half year journey by slipping neatly into orbit around Mercury.  “This mission will continue to revolutionize our understanding of Mercury during the coming year,” said NASA Administrator Charles Bolden, speaking at MESSENGER mission control. “NASA science is rewriting text books. MESSENGER is a great example of how our scientists are innovating to push the envelope of human knowledge.”  This is the first time a spacecraft has ever orbited the … Continue reading →

13 March 2011

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Not much to report.  I put in an hour’s grinding, one third stroke centre over centre, using the #220 grit, and STILL haven’t restored the bevel.  I’m playing with fire by putting that off…  Under the magnifier, the surface looks much the same – it isn’t obvious that there are fewer pits than before, except for one thing:  The pit density at the centre is about half that at the edge.  Since the grinding technique always causes more wear at … Continue reading →

Hubble strengthens case for Dark Energy

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Researchers using new data collected by the Hubble Space Telescope (HST) have refined our estimates of the rate at which the Universe is expanding to an uncertainty of only 3%.  This new figure invalidates the idea that our region of space is situated in a vast unusually empty bubble, or void, which has up till now stood as an alternative to the Dark Energy hypothesis. Albert Einstein recognised that the Universe could not be static, based on physics as he … Continue reading →

6 March 2011 – Two hundred and twenty

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There’s something marvelous about moving on to the next finer grade of grit.  The long work building up to it means there’s a huge sense of reward.  The careful clean-up process gives it a sense of occasion.  The different feel and sound of the grinding gives it novelty.  I love it! So I recently got tired of the relentless grinds which seemed to make no progress.  I was producing a beautifully smooth, spherical surface, but not gaining any depth.  My … Continue reading →