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!

SKA: South Africa wins approval of Science Board

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We’re getting closer to knowing whether South Africa or Australia will win the bid to build the Square Kilometer Array (SKA), a vast radio telescope which will span a radius of thousands of kilometers and allow astronomers to peer further and deeper into the cosmos than ever before.  SKA’s site advisory committee announced on 10 March 2012 that they had selected the Southern African site as being the better choice, although they emphasized that the decision had been difficult as … Continue reading →

Solar Flares

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As anybody with an internet connection has heard, on 21 December 2012 various events will coincide:  The appearance of the dread planet Nibiru, the alignment of the Solar System with the galactic core, the end date of the Mayan Long Count, which will cause (via various pseudo-scientific mechanisms) the Sun to go crazy, belching out Solar Flares which will strip the earth of its protective atmospheric layers and snuff out life on earth.  Gosh! Before we go on, I need … Continue reading →

The luckiest man in the world

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Things have gotten quite busy at work – servers have crashed, and I’ve been putting in a lot of late nights putting out fires, rebuilding services and restoring backups.  This has left me no time at all for mirror grinding, so yesterday afternoon at the Class was the first bit of work I’ve managed since last time.  I made a near-fatal error, however, which almost ended the project right there… Johan was there with an interesting toy:  a vintage naval … Continue reading →

What does Mars weigh?

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Mars does not have a weight, but does have a mass of about 6.4 x 1023 kilograms, which is a little more than a tenth that of Earth.  When astronauts or spacecraft orbit the Earth, we describe them as being weightless, because they are in freefall.  They are not resisting gravity (the way your body does when you stand on the ground) so “Weight” becomes a totally meaningless concept when you’re in space.    Written by Allen Versfeld Comments?  Questions? … Continue reading →

What does Venus weigh?

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Don’t you know you’re never supposed to ask a lady her weight?  I can probably get away with telling her mass, though, which is about 4.87×1024 kilograms (Or to write it in tonnes: 4870 million million million tonnes).  That means that Venus has about 82% of the Earth’s mass.  Of course, mass and weight are two totally different things (even though the units we normally use for them happen to match up on the surface of the Earth).  Like all … Continue reading →