A while ago in my MicrobiologyBytes blog, I wrote about how many different kinds of bacteria there are on Earth. This proved to be a very popular topic, so in this week’s podcast, I describe recent work which explores a more direct but still not a simple question: How many different bacteria are there in a gram of soil? The answer may surprise you.
No longer a lonely planet. Photo: Miguel Ugalde
The fall out from the IAU gets more and more amusing from a non-astronomer’s point of view. The definition has some major problems in it. The two important parts of Resolution 5A are
(1) A “planet” is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.
(2) A “dwarf planet” is a celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape , (c) has not cleared the neighbourhood around its orbit, and (d) is not a satellite.
There’s big argument you could have about “How round is nearly round?” but that will be sorted out at another meeting. No, the real rake in the grass is section c:
(c) (has / has not) cleared the neighbourhood around its orbit.
Pluto is no longer a planet because it hasn’t cleared Neptune from its neighbourhood. Neighbourhood is another problem word, but it’s the logic that’s the real problem. If Pluto hasn’t cleared Neptune then no can Neptune have cleared Pluto – it can’t be a planet either. I worked this out as I read Phil Plait’s entry on the topic and was feeling pretty smug about this line of reasoning until I saw further down the page that he’d noticed it too. It is an obvious hole. But where does this leave Earth?
Near Earth asteroids are potentially a huge danger. That’s why Spaceguard was set up. Therefore it’s clear that Earth “has not cleared the neighbourhood around its orbit” and thus isn’t a planet. Nor is Jupiter. Among other things Jupiter is known for its accompanying Trojan asteroids. So it can’t be a planet either. In fact I’m not sure any of the named eight planets in the release meet all criteria for being a planet.
The argument is going to continue until astronomers have an idea about what they want the term “planet” to do. The ongoing wrangling seems to be symptom of various different space scientists arguing tangentially rather than address the issues that bother them.
As biology becomes ever more complicated, so the ethical questions involved multiply.
BioethicsBytes is a new online resource from the School of Biological Sciences at the University of Leicester which hosts a collection of resources to assist in the teaching of bioethics. We hope you will find this helpful repository and if you have additional materials that you’ve found useful and are willing to share via this medium, then please feel free to send a comment to let us know.
You may have heard that a government report says that a third of adults in England are set to be obese by 2010 unless action is taken. Eating less isn’t much fun, so clearly the answer is more exercise. Here’s how!
This is how a planet ends.
Photo: The International Astronomical Union/Lars Holm Nielsen
The elephants were gathered on the savannah a respectful distance from Nellie, the matriarch. She had to break some bad news to one of the herd. Nellie looked down with her big regretful eyes at the somewhat smaller member of the herd standing in front of her. “There’s no easy way of telling you this.You were adopted,” she said to the tiny creature. “In fact you might not even be an elephant. We think you’re an ant.”
The vote of the IAU has been announced. The press are saying it’s a turn around from the position they took on Sunday, but it’s not. Before there were going to be eight classical planets and Pluto as a planet. Now there are eight planets and Pluto as a dwarf planet. Quite simply “One of these things is not like the others…”
It’s not the first time that astronomers have changed their mind about something being a planet. The difference is that this time round the ejected planet has come away with quite an honour.
It helps if you know what a planet is – which is where the fuss started.
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RNA interference (or “RNAi”) is a mechanism where fragments of double-stranded RNA interfere with the expression of a particular gene. RNAi is receiving a lot of attention. One reason for this it that it has potential potent antivirus actions, but as you’ll hear in the latest MicrobiologyBytes podcast, there are problems with delivery at the present time.
If you’re feeling a little down with the new academic year starting to loom after the bank holiday, you might “enjoy” Exit Mundi, where you can ponder how it’s all going to end. And I always though of the Dutch as rather cheerful people…