Tag Archives: Planet

Podcast #1: Seven earth-like planets

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Wow, we finally did it!  The podcast is alive, and this is the first episode!  In this episode, I cover probably the biggest astronomy news item of the year so far, and also read one of my more recent opinion pieces.  I know, you could just read it yourself, but it’s something I feel quite passionate about, and wanted to let you hear it in my own voice. As long-time readers will know, this is something I’ve been threatening to … Continue reading →

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Mercury

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Mercury is one of The five classical planets and an easy naked eye object.  The planets stood out from the other stars to our ancestors because of the way they all moved in regular patterns against the night sky, but Mercury was unique in its rapid motion and the way it never strayed far from the sun.  If the planets were to be named for gods, then it was only natural that the flighty mercurial one should be their messenger. … Continue reading →

How many moons does Jupiter have?

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Current total: 79. I’ll keep updating this page as more get discovered. Details in the UPDATES section below As of 2 February 2012, we know of 67 moons around Jupiter.  We will probably continue to find more and more, as we keep looking, since Jupiter is large enough that it constantly captures passing asteroids and comets, turning them into moons.  The smallest ones are so hard to see, and have such big irregular orbits, that astronomers sometimes lose them, until … Continue reading →

What does Jupiter weigh?

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Jupiter has a mass of about 1.9 x 1027kg – 1900 trillion Trillion kilogrammes.  That’s more than double all the other planets, asteroids, comets and dust of the entire Solar System put together.  Jupiter is BIG, yet still manages to not weigh anything at all.  How?  Because it is in orbit around the Sun, just like an astronaut orbits the Earth, and so experiences zero gravity.  That’s not to say there is no gravity around Jupiter – it has plenty gravity … Continue reading →

The Scale of the Solar System – a 3rd attempt

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Some time ago, we featured a poster created by the Planerary Society’s Emily Lakdawalla which showed all of the Sun’s largest satellites (or at least, everything we know of that’s bigger than 400km across), to scale.  She has since refined the image to correct perspective effects that made Saturn look bigger than Jupiter, and you can see the result to the right.  Gas giants, rocky planets, minor planets, asteroids, moons, they’re all there.  Click the image to see it in … Continue reading →