Planets past Pluto

Interesting stuff... discussions around "Planet X" have taken place since Percival Lowell in the early part of the 20th century... which led to the discovery of Pluto by Tombaugh in 1930 (the first two letters of the name "Pluto" are, of course, the initials of Lowell... in honour to the contribution he made to the discovery).

However, Pluto was not of sufficient mass based on Lowell's calculations, but we discovered recently that this was because an incorrect mass of Neptune was used in the calculations.

If there are more planets at 200-250 AU, we will have quite a job trying to observe them. That's one hell of a long way out!!

I hadn't heard the story about the 'PL' in Pluto - only the story about the young girl in England who suggested the name. There's a podcast (and transcript) on the Nasa website with a 2006 interview with her that discusses the point, concluding that the first two letters of her suggestion may have been an important factor in the decision to call it Pluto.

BTW, while a New Scientist story the other day referred to a planet hiding 'beyond' Pluto, their tweet to link to the story said "There is a hidden "Planet X" lurking behind Pluto". I replied asking if that meant we needed to rewrite Kepler's third law...

Lurking, makes it sound perverse. Like some sort of stalker.

With all the success of finding exoplanets thus far, its ironic that we may not have found all of our own solar system planets! Was it not suggested that the expected normal structure for a planetary system was to have rocky planets further out orbits and large gas planets within the inner orbital zones. Thus, our solar system is of a non standard structure? So if there are more larger than earth rocky planets further out, then our solar system might be edging towards being slightly more normal than first thought 🙂

http://www.bbc.co.uk/news/science-environment-34615229