... also referred to as minor planets or planetoids (not to be confused with "lesser planets" which refers to Mercury and Pluto ... If a piece of it survives to reach the Earth's surface it is known as a meteorite . ...
... shape), like the craters on Callisto , without the high ring mountains and central peaks commonly seen on the Moon and Mercury ... As it froze and expanded, the surface must have cracked to accommodate the extra volume producing Ithaca Chasma. ...
... Mercury could be solved by assuming an intra-Mercurial planet, or possibly a second ... smaller than Mercury's and its mass was estimated at 1/17 of Mercury's mass ... above the Earth's surface and perigee at just 11.4 km (!) above the Earth's surface ...
... just define "planet" as "one of Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus ... would mean that some places on the surface are farther from the center than others ...