Fictional planets of the Solar System 40 Eridani A. Counter-Earth was a hypothetical planet sharing an orbit with Earth, but on the opposite side of the Sun (hence Earth and Counter-Earth would always be invisible to each other). The idea of a counter-Earth has never been a serious scientific hypothesis in modern times. Phaëton is a name given to a supposed planet existing in the past between the orbits of Mars and Jupiter, which no longer exists, having become the Solar System's asteroid belt. Proposed not long after the discovery of multiple asteroids at the beginning of the 19th century, the idea that the asteroids were
Lada Terra as well as many other features that scientists use to attempt to piece together the history of this complex planet. The distinctive cross-cutting relationships found in the bedding of Lada Terra have been important in realizing relative ages of the extensional belts and coronae, as well as the complex tesserae features present planet-wide. In 1990 the Venus Radar Mapper revealed the largest outflow channel system on the planet located in the northern region of Lada Terra. Although Lada Terra is generally considered a highland of Venus, the topography is much lower-lying than its northern counterparts Ishtar Terra and Aphrodite Terra.