Comet or asteroid: what is the difference?

Because looking up the difference between a comet or asteroid drives me nuts. They are both: Small chunks of “stuff” that hang around in the solar system. Most describe some sort of orbit, but some pass once and we never see them again. The vast majority can’t be seen with the…

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Jupiter’s moon Io: some facts

His Name In Lights is set on Jupiter’s moon Io, which has captured my interest for some time. I have at least one other Io story in the making. Expect an announcement about A Perfect Day Off The Farm fairly soon. In that story, I explain the concept of stick…

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Looking at the Earth through different eyes: the GRACE mission

Adapted from a talk given at #CSIROTweetup by Dr Daniel Shaddock (laser systems) Dr Paul Tregoning (geo data) ANU, supplemented with data from the GRACE mission home page. Image snarfed from the NASA/JPL GRACE page Most people associate going into space with exploring objects not on Earth, but many satellites…

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Mars Curiosity Tweetup in Canberra!

On 25 November 2011, NASA will launch the Mars Science Laboratory mission in the form of the rover known as Curiosity, which will be the third such rover to be trundling about the red planet. Curiosity (follow on Twitter as @MarsCuriosity) is larger than the previous two, Spirit, which famously…

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How is the size of a planet related to its atmosphere

People have asked me to write something about terraforming Mars, a subject that is of great interest to Science Fiction buffs. I think Kim Stanley Robinson in his Mars series does a pretty good summary of all the currently-held scientific opinions on techniques of how we could achieve this. Yes,…

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What if the Earth had no moon (part 2)

In a previous post, I mused about what the earth would be like with no moon. You may hear the Moon blamed for things as diverse as reproductive cycles and people’s moods, but in that post, I argued that if all of a sudden, we’d find ourselves without a moon,…

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Once more on the search for exoplanets, and Alpha Centauri

This morning I came across this very interesting article on the Centauri Dreams website. By the way, Centauri Dreams, the website of the Tau Zero Foundation, is a very rich source for writers of realistic SF, especially in relation to planetary exploration and interstellar travel. The article summarises results and…

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Communication in space

Electromagnetic waves, whether gamma ray, microwave, radio or visible light frequencies, travel through vacuum at the speed of—well, uhm—light. When on Earth, this means communication is pretty much instant. If the distance travelled in one second by a photon, a light particle, were a string, it would wrap around the…

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What would earth be like without the Moon?

The search for terrestrial extrasolar planets in the habitable zone of stars suggests that these planets may not be all that rare. However, examination of the solar system points to the fact that planets with a satellite similar to the Moon are probably a lot less common. It is massive…

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Exoplanets: could Alpha Centauri have any?

My fiction recently gave me cause to examine interstellar travel. Many writers tend to shy away from the reality that we’re a long way from anywhere. It’s too hard, too intimidating, too depressing. I, too, have done the wormhole thing, you know, where your characters can zip between worlds, but…

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