Weird Science - Heavens Above!

It is surprising to think that less than fifteen years ago we knew of no planets but those in our own solar system. Now astronomers discover them with such frequency that it takes finding a potentially habitable one like Gliese-581d to stir the public’s interest. But a British team at the Isaac Newton Telescope on the Canary Islands may have done something much more amazing than finding another planet in the Milky Way, they believe they may have just detected one in another galaxy. The object orbits a star in the Andromeda galaxy, more than 2.5 million light-years away from Earth, causing that star to wobble. Normally any motion would be invisible at such a distance, but by chance the distant solar system is acting like a lens in front of even more distant stars, and every wobble of the lens is magnified enough to be discernable (Scientific American).

Closer to home, relatively, is the planet is known only as WASP-18b, but if it were ever to be given a proper name it would be “Icarus”, for this is a planet that has flown too close to its sun. WASP-18b is the 375th extrasolar planet discovered by astronomers, and is possibly the most extreme one yet. It is another gas giant like Jupiter, but ten times the size of our neighbourhood giant, yet it orbits its star in less than a day. This 22.5 hour long “year” would mean the planet is so close to its sun, and moving so fast, that tidal forces are almost certainly dragging the planet inwards to its doom. The team from Keele University that discovered WASP-18b, led by Coel Hellier, calculate that realistically the planet probably has less than a million years left (Nature).

But perhaps we shouldn’t feel so smug in our safe little backwater. In another paper from Nature, J. Laskar and M. Gastineau of the Observatoire de Paris report that in a study of 2500 possible futures for our solar system, in 1% of cases Mercury’s orbit became so unstable that it collided with either Venus or the Sun. Another scenario saw the orbits of the inner planets descend into chaos, putting Earth at risk of a collision with Mercury, Venus or Mars. The good news is that you don’t need to hide under the bed just yet, none of this is expected to occur for billions of years (Nature).

But, for all its violence and destruction, the universe is still an amazing and beautiful place. One such delight is a cosmic bubble, as perfect as any blown by a child, albeit one 20 trillion km across. It’s a planetary nebula, the remains of a star that has run its course and exploded, throwing huge shells of gas and dust into space, and lies in the constellation of Cygnus. Frequently these nebulae are spun into incredible shapes that are named for their resemblance to butterflies, hourglasses or eyes, but for me the Cygnus bubble is just as magnificent in its simplicity (New Scientist).

(Image sources: Case Western Reserve University, Kitt Peak Observatory.)