As photographers in the US are gearing up to capture photos of 4th of July fireworks, NASA has released a gorgeous “fireworks” photo of its own. It’s a shot of a “the galaxy’s biggest ongoing stellar fireworks show” that started 170 years ago. Eta Carinae is a doomed super-massive star 7,500 light-years away that went through a “Great Eruption” in the 1840s that made it the second-brightest visible star in the sky for over a decade — it was so…