Science?????s Holy Grail


I see the ongoing quest for other Earth-like planets has turned out a so-called mini solar system

Far be it from me to be purist about such matters, but I?????m not sure ?????mini solar????? is the best description of these systems. Most of the planets so far discovered outside our solar system (latest count 136) have been found orbiting stars very much like our jolly old Sun. You know the sort of thing; middle-aged, unspectacular, and predictable – quite like Prime Ministers really.

This new finding, however, is that of planets which orbit small, failed stars, known as brown dwarfs. Not like our solar system at all in fact.

You see, planets are not what they used to be.

There was a time when we felt comfortable about the distinction between planets and stars. Planets we could land rockets on (though you usually had to be careful that Captain Kirk wouldn?????t attempt the odd snog), and stars shone.

Nowadays, it?????s not so simple. Since a giant gas planet like Jupiter is very similar to the Sun in composition (lots of hydrogen, some helium and just a dash of everything else!) the boundary between planets and stars is a lot more fuzzy. There?????s a sort of planet-star continuum with the most important determining factor being the mass of the body concerned. Essentially, if the sphere mass is large enough, then nuclear explosions are triggered in the core and a star is born, as they say.

And spherical bodies in this continuum whose bulk lies between roughly 13 and 80 Jupiter masses are known as brown dwarfs. They?????re big enough to burn, but not quite big enough to become fully-fledged stars like our Sun.

The star at the centre of this new unearthing, named OTS 44 , is only about 15 times the mass of Jupiter, so its quite a small brown dwarf, and some reports are questioning whether life could exist on planets in orbit around such dwarfs?

Well a planet needs to be close enough to its parent star to benefit from its life-giving warmth. And in the case of cool dwarf stars, that?????s pretty close! So close, in fact, that the planet may very well be locked in its orbit, always keeping one hemisphere facing the star, just as the Moon does to the Earth.

Now, you may ask what?????s the problem with that? Seems that such orbitally-locked planets will heat up on the “starside”, and get extremely cold on the other! So cold that the whole atmosphere could condense on the ?????darkside?????. This would prevent life developing on the planet surface.

But there is always a dialectic in science. If the atmosphere of a locked planet were sufficiently massive, then its circulation could carry summer from the ?????starside????? of the planet to the ?????darkside?????.

In the search for life beyond the home planet, science?????s holy grail, hope springs eternal.


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