Answer:
Formation of Earth. Earth came together (accreted) from the cloud of dust and gas known as the solar nebula nearly 4.6 billion years ago, the same time the Sun and the rest of the solar system formed. Gravity caused small bodies of rock and metal orbiting the proto-Sun to smash together to create larger bodies.
Mrs. White is a strong woman, and the narrator even says she's smarter than her husband. We get the sense that she makes lots of decisions for the family and that her husband is happy with this reversal of traditional gender roles.
As mentioned in Mr. White's section, she might go a bit too far sometimes, to the point of forcing Mr. White to do things he thinks are wrong, like wishing Herbert back to life. Some readers see her as mean and dominating.
The answer is "when the surrounding words are unfamiliar".
