Hello….what have we here?
Yes, two for the price of one and you can see this in real life - only if you have a powerful telescope and know where to look in the constellation of Sagittarius the Archer.
Do you remember swatting for science tests with the mnemonic: "My Very Educated Mother Just Sent Us Nine Pizzas" for the 9 planets - 4 terrestrial (Earth-like), 4 gaseous and mysterious Pluto?
Well you can forget the pizzas because they're now telling us that Pluto is too much of a misfit to be called a planet. It's much neater to just have 8 ‘peas in the pod’: 4 terrestrials and 4 gaseous, and demote Pluto to a dwarf planet or ‘TNO’- Trans Neptunian Object.
The problem is the other ‘terrestrials’ aren’t really Earth-like, and the 8 planets certainly aren’t ‘peas in a pod’ but all very UNIQUE. (how come?) No two planets are alike - but Pluto is just too unique!
(The PL in ‘Pluto’ acknowledges Percival Lowell.)
So what do we know about Pluto?
·
Believed to comprise rock and frozen methane· A methane atmosphere
· Still active volcanically! (The ‘god of the dead’ is not so dead!)
· A retro rotation about an axial tilt of 122.53 degrees from its orbital plane
· The coldest ‘planet’ in our solar system, at minus 225 degrees C (cold enough?)
· A solar orbit inclined 17 degrees, so elliptical that it passes inside the orbit of Neptune for 20 out of 248 Earth years
· 3 minor satellites known as: Nix, Hydra and P4
…and how about this?...
In 1978, astronomer James Christy found Pluto had a sibling – a moon half its size, Charon (‘ferryman of the dead’), which orbits Pluto every 6.4 days and they constantly face each other in a ‘tidal lock’-
just like two angry brothers, very much alive, facing off for a fight in the freezer room!
(Pssst!……..whatever did Jim’s wife, Char, think of
having a frigid moon named after her?)In 1978, astronomer James Christy found Pluto had a sibling – a moon half its size, Charon (‘ferryman of the dead’), which orbits Pluto every 6.4 days and they constantly face each other in a ‘tidal lock’-
just like two angry brothers, very much alive, facing off for a fight in the freezer room!