Roughly 4.5 million years ago, the sun passed remarkably close to two intensely bright stars whose radiation flooded nearby space — and the encounter left a ghostly scar that astronomers can still detect today, according to a new study.
The research team says the close pass helps to solve a decades-old mystery of why the space around our solar system is far more energized than models predict, including why it contains a surplus of ionized helium.
