why does my right ball hurt - SportsID
"why" can be compared to an old Latin form qui, an ablative form, meaning how. Today "why" is used as a question word to ask the reason or purpose of something. This use might be explained from a formula such as "How does it come that ...".
Understanding the Context
If you meet an old friend of yours, whom you never expected to meet in town, you can express your surprise by saying: Why, it's Jim! This why in the ... So, why does she ever tweet with standard capitalization (and do so quite randomly and quite frequently)? In contrast to the other answers, my answer (typing in only lower case is simply faster) explains the above tweets quite simply: Why do people use the latter terminology?
Image Gallery
Key Insights
For one thing, I find it confusing. It doesn't help that BCE is similar to BC. But moreover, there is only one letter of difference between the two terms, whereas with BC and AD, the terms are clearly different and I find it easier to distinguish! Were BCE/CE established earlier than BC/AD?