A San Francisco teacher has been left with a partially melted car after he left a curved mirror sitting in the rear on a sunny day.
Marc "Zeke" Kossover wrote on the website Phyzblog he intended to take his improvised solar oven in to work at Exploratorium Museum of Science to show off, but accidentally left it in the car.
The solar oven was made of an old satellite dish covered in reflective material capable of reflecting light and creating heat.
It sat there through the sunniest part of the day, reflecting the light and heat directly onto the back of Mr Kossover's Subaru outback.
When he got back in the afternoon he didn't notice anything amiss until he looked in the back mirror and saw melted plastic.
Heat had chewed through the plastic covering the metal in Mr Kossover's car and left it dripping down onto the reflective surface below.
"The hot spot wasn't super small, it was hot. Really hot. It can pasteurize a litre of water in 15 minutes," Mr Kossover said.