Cumbrian Sky

FINALLY I've got time to cover the Big News that broke last week!

If you turned on your radio or TV on Tuesday night you'd have seen or heard the news that scientists (or "Boffins" if you read the Sun's report!) have discovered a fifth planet around the star 55 Cancri. Many reports went on to add two and two and get fifty by breathlessly adding that "scientists are excited by the discovery because the planet is in the right position to have water, and maybe life too - "

(cue screech of brakes)

WHOAHHH!!! Hang on! That's not the story at all! Let's look at the facts.

55 Cancri is a star a lot like our own Sun - it's the same mass and age as our own star, but just a little fainter - that lies 41 light years away from Earth. As its name suggests it appears to be in the constellation of Cancer as seen from Earth, and although it isn't one of the brightest stars in the sky it is visible to the naked eye and a simple pair of binoculars shows it very well.

By Tuesday morning we knew of 220 planets orbiting other stars out in space. Astronomers call them "exo-planets". And scientists already knew there were four planets orbiting 55 Cancri... but the discovery of the fifth one (given the imaginative catalogue name of "55 Cancri F"... yawn...) is the Big News because it orbits in the star's habitable zone, that's basically the "band" around it where, basically, the conditions allow for the existence of liquid water. Astronomers often also call this zone the "Goldilocks Zone" because, like baby bear's porridge that fed Goldilocks when she did her famous bit of breaking and entering and burgled the Three Bears' cottage, it's not too hot and not too cold... it's just right.

The thing is, this planet is NOTHING LIKE EARTH, despite what some newspapers and news reports said. "F" is a huge "gas giant" planet, 45x more massive than Earth, a world, like our own gas giants Jupiter and Saturn, made of gases and liquids and with no solid surface. So, there's no "surface" for liquid water to exist on, and, therefore, almost certainly no life waiting to be found there, either.

However... and THIS is the actual scientific blockbuster news... because we see them orbiting our own solar system's gas giants, it's very possible, if not likely, that "F" will have one or more large moons orbiting it too, and it's possible that they have liquid water on their surfaces which might mean they're able to support life.

So, the story is this: no, we haven't found "another Earth"; we've found a gas giant planet around another star, a planet that is in just the right place for water to exist on any large moons it might have, and if there's water there's a CHANCE there might be life too.

Above: artwork by space artist Lynette Cook showing what 55 Cancri F might look like, cmplete with a "terrestrial moon" withw ater and possibly life.

If you want to learn more about this fascinating story, and see some great computer animations that illustrate it, just go here.

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• #1 Comment from memes121 
  11/10/07 9:10 AM | Permalink

  I guess some will have to unpack again. Tammy