Neptune and Pluto
Neptune was added to the eight planets on September 23, 1846 by Johann Gottfried Galle, of the Berlin Observatory
No new planets have been added 08/2011
Two Planets was created in 1897.
The two planets with overlapping orbits are Neptune and Pluto. These are the only two planets that have overlapping orbits.
Two types of planets are terrestrial planets, which are small, rocky planets like Earth, and gas giant planets, which are large planets primarily composed of hydrogen and helium, such as Jupiter and Saturn.
Mercury and Uranus are the two planets that are farthest apart.
The other two planets are Mercury and Venus.
The first two planets discovered were Earth and Mars.Another Answer:The first two planets, with respect to the Sun, are Mercury and Venus.
Mercury and Venus are the two planets that have no moons.
A Dweller on Two Planets was created in 1905.
Earth and Venus
In Planetary Science the two largest planets are Jupiter and Saturn.