Perhaps I mangled that a bit, instead of frost line I should have just said the seemingly most popular theory of how the solar system formed. From the article

Perhaps I mangled that a bit, instead of frost line I should have just said the seemingly most popular theory of how the solar system formed. From the article the bit that caught my eye: Mike Brown, an astronomer at Caltech, wrote me that while everybody is busy hunting for an Earth-like planet, they missed this story. "Before we ever discovered any [planets outside the solar system] we thought we understood the formation of planetary systems pretty deeply." We had our frost line. We knew how solar systems formed. "It was a really beautiful theory," he says. "And, clearly, thoroughly wrong."