Historically, "earth" has been written in lowercase. From early Middle English, its definite sense as "the globe" was expressed as "the" earth. By Early Modern English, many nouns were capitalized, and "the earth" was also written "the Earth", particularly when referenced along with other heavenly bodies. More recently, the name is sometimes simply given as "Earth", by analogy with the names of the other planets, though "earth" and forms with "the" remain common. House styles now vary: Oxford spelling recognizes the lowercase form as the most common, with the capitalized form an acceptable variant. Another convention capitalizes "Earth" when appearing as a name (for example, "Earth's atmosphere") but writes it in lowercase when preceded by "the" (for example, "the atmosphere of the earth"). It almost always appears in lowercase in colloquial expressions such as "what on earth are you doing?"