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!

What was the Star of Bethlehem?

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Merry Christmas to all readers (Not just the christian ones, since Christmas long since transcended a celebration of the Christ.  It’s even a huge deal in Japan, with less than 2% of the population reporting Christianity, for pete’s sake!), and a Happy New Year to you. Around this time of year, astronomers are often asked “What was the star of Bethlehem, exactly?”.  It’s a difficult question, because we have so little information to go on, and what we have precludes … Continue reading →

The beginning

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It’s time.  For years I’ve been pawing at advertisements in astronomy magazines, and browsing through ATM (Amateur Telescope Making) guides and handbooks, but I’m still doing my astronomy through a rather nice pair of binoculars.  I haven’t looked through a telescope since 1995 (beautiful 100mm refractor that my uncle kindly loaned me for about a year), and that has got to change. So, this Saturday afternoon I will drive down to Parktown Boys High School in Johannesburg and join an ATM class.  … Continue reading →

Why Akatsuki Failed

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Artist’s impression of Akatsuki in orbit around Venus. Credit: JAXA On 8 December 2010, the Japanese Space Agency (JAXA) announced that their Akatsuki probe had failed to achieve orbit around Venus.  Having successfully launched six months prior, it’s trajectory had led it on a long curving path towards Venus.  To enter Venusian orbit, it needed to reduce speed by firing its main engines forward for 12 minutes (a maneuver called an Orbital Insertion Burn).  It would then have been perfectly positioned to … Continue reading →

December Solstice

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In a little more than 24 hours time (at 03h38 UTC, on 22 December 2010) the Sun will reach it’s southernmost point in our skies and begin moving back North.  Or, to put it in a slightly less geocentric way, the Earth will pass through the point in it’s orbit where the south end of its polar axis will come closest to pointing at the Sun.  This is called a Solstice.  The December solstice marks the official beginning of Winter in the Northern … Continue reading →

Odyssey takes the lead

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NASA’s Mars Odyssey orbiter took the lead Wednesday as the spacecraft which has served longest studying Mars.  As of yesterday, Odyssey (which left Earth in 2001) has been in orbit around Mars for 3340 days.  The previous record was held by the Mars Global Syrveyor, which server from 1997 to 2006. Odyssey has achieved a lot over the last nine years.  It has continuously monitored seasonal changes on Mars from year to year, compiled the most detailed maps ever of the martian surface and … Continue reading →