Lyric discussion by kateb0 

on yessaid.com there are interviews regarding the song.

she said that during the 'under the pink' tour in phoenix, a ghost came and sat on the edge of her bed and sang a song. he led her into the bathroom, still singing, and she turned on all the hot water and its noise harmonized with his singing. he then drew her a picture on the steamed mirror. she interpreted it as being "that earth and Jupiter were in love billions of years ago, then they were separated, and now they are billions of miles apart, and this is earth’s love song to Jupiter."

at the time, she was in a really rough patch and indeed, as she said herself, involved in "a love triangle".

i think the ghost was trying to help bring her to this apocalypse where she could see that the way she had "looked at relationships with men and put them on a pedestal is over."

the man she had called over and over was in particular Eric Rosse, and i'm gathering that Jupiter symbolizes him.

i also wonder about Fairycake's idea; "...In a self destructive move she has sex 'little macochist is lifting up her dress' with the other guy in the triangle because she needs someone to run to."

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