Pluto

Pluto is getting a huge amount of press from NASA
due to the new Horizons probe's closest approach to pluto tomorrow. 
latest images can be seen here

Here's pluto back when it was still a planet in July 2006:



because of it's great distance, 
both visually and photographically from earth, 
pluto is just another white dot in a field of stars
which can be distinguished only by the fact that it moves across the stars (in this case the images were taken over several different nights).  

here's a recent image by fellow OCastronomers member Tom Munnecke

pluto has 5 known moons, perhaps more to come.  it's largest, charon has half the diameter of pluto.  As a result, the center of mass of the system (and their combined orbit) lies outside of pluto; they orbit eachother (one of the less valid reasons for demoting pluto)

The book
How I Killed Pluto and Why It Had It Coming by Mike Brown
gives an interesting account of why pluto should not be a planet (eccentric orbit, small size, etc), pointing out the fact that there were a number of asteroids (ceres etc) that had been planets, but were later demoted.  credit is due to the astronomical societies for waiting 5 years after the death of Clyde Tombaugh, it's discoverer, before demoting it.  credit is also due to Mike Brown who helped demote it, having discovered (with his team) 2 more "transneptunian objects".  Had he made the case for pluto's planet-hood, he would have made the case for his discoveries, becoming the only living planet discoverer, and the only one to have discovered more than one.  
It also gives a remarkably restrained account of one of the slimier moves in the astronomy world: a group from Spain saw an abstract title for an upcoming meeting,  peeked at the server logs, determining the location of the object mike brown was studying, then claimed the discovery as their own, without so much as a reference to the US group.  
The book is actually a good read, thanks chris


Here's one of his discoveries:

Transneptunian object 2005 FY9 a/k/a Easter bunny passing egg shaped galaxy ngc 4314 2/22/2006.  
This dwarf planet is now named Makemake (god of fertility in the mythology of the Rapa Nui people of Easter Island).  discovered around easter when his wife was pregnant...