Planetary symbol: ♁
Terra is the third planet from the Sun, and is of course the beautiful blue marble upon which we live. Although the Earth is not officially known as Terra according to the International Astronomical Union, authors have referred to it as such for decades and is the name whence the words terran, terrestial and terraform (to list a few) are derived.
Terra has no specific significance in astrology because it is not a body that is observed to pass through any of the "houses" (astrology being based on a terracentric model of the planetary system as opposed to a heliocentric one), but it was nonetheless recognized as powerful and divine by the ancients. In Greco-Roman mythology, Terra (Greek name: Gaia) is the goddess of the Earth and was prayed to for fortune in agriculture as well as protection in the wake of natural disasters.