Permanent Human Settlement of the Earth, Space and Ocean Frontiers

Sunday, March 19, 2006

Whats Out There?

View from Sedna

Ralph Buttigieg

Sydney, NSW, Australia

Dennis has written about the recently discovered Kuiper Belt Object, UB313 now known to be larger then Pluto. The International Astronomical Union still can't decide what a planet is so it doesn't have a proper name. Its discovers have given it the temporary name of Xena and are calling its moon Gabrielle after the characters of the Xena TV show. Personally I think Xena is a perfectly good name for the new planet. After all everyone who watched the TV show knows Xena was a Greek demi-goddess who's father was properly Ares (Mars). However I doubt the astronomers of the IAU will be so open minded. As UB313 sounds like the name of one of the forms I processed while I worked in the public service, I'll call it Xena until the IAU come up with something better.

The mysterious depths of our solar system are like the unexplored regions of the 18th Century world. Navigators knew the Northern Hemisphere fairly well but much of the Southern Hemisphere was a mystery. Scientists of the time believed the Southern Hemisphere had to have a large super-continent similar to Eurasia. They thought the Earth was like a wheel and had to be kept in balance and a large Southern continent was required to keep the Earth spinning properly . That was one of the reasons Captain Cook was ordered to explore the South Pacific. He did not find the huge land mass but he did find the smallest continent, Australia.

Today I'm going to stick my neck out and make some WAGs on whats out there, Hopefully they will be more accurate then my Melbourne Cup racing tips but here goes.

Bodes Law and Planet X ,Y and Z

I have never been much of a mathematician but the mathematical progression known as Bodes Law has always fascinated me. Its a way of calculating the distances of the planets from the Sun and is very simple. Take these numbers 0, 3, 6, 12, 24, 48, 96. As you can see after the first two we are just doubling the number.

Then add 4 to each number: 4, 7, 10, 16, 28, 52, 100.

Finally divide by 10: .4, .7, 1, 1.6, 2.8, 5.2, 10.

The numbers match up reasonable well with the actual distances of the visible planets in Astronomical Units. Theres a missing object at the 2.8 position but in 1801 the minor planet Ceres was discovered and that fits in the gap nicely. In the years that followed many other small objects were discovered at approximately 2.8 AU distance and we now call the region the Asteroid Belt. Astronomers expected to see a continuation of the progression for any new planets and were not disappointed when William Herschel found Uranus in 1781 at 19.9AU.

However Neptune was found in 1846 and it came in at 30.1 AU not the expected 38.8AU. The “Law” fell into disrepute after that and has never really recovered.

Amateur astronomer Clyde Tombaugh discovered Pluto in 1930 and interestingly it has average distance of 39.5 so does seem to fit. We now know that Pluto is a Kuiper Belt Object and like the Asteroid Belt there are other objects at roughly the Bodes Law distance.

Are there any more objects out there even further out? Well Xena at the moment is the most distant object known it has an elliptical orbit takes takes it back to the Kuiper Belt then out to 97AU. But a couple of years ago Sedna was discovered. This little world seems to be an Oort cloud object, the Oort Cloud being the hypothetical shell of icy proto-comets in very loose orbits around the sun. Sedna's orbit is highly elliptical but its perihelion is a 76.1 AU not far off the Bode Law expected 77.

So what is going on here? No one knows if the “Law” is just an oddity or there is some unexplained harmony in the Solar System. But its seems that while not all objects fit in the Bode Law distance points all such points have objects in them. So this is what I think. Just us we found other objects around the little planets Ceres and Pluto distances we will find more objects at the 77AU Sedna distance to make up the extra mass. Also expect to find substantial objects at the 154 and 307.6 AU distances the next two Bode Law numbers.

I think the next few years are going to be very interesting. As Captain Picard would say “Lets go and see whats out there”