Mars
Mars is an inner planet, as is Mercury, Venus, and Earth.
It can be sometimes, but Venus can be closer than Mercury ever can; Mercury is only the closest planet to Earth when Venus is on the opposite side of the Sun from Mercury and Earth, and maybe not even then (depending on exactly where Mars is).
Mercury (planet) is the nearest planet to the Sun.Planet Mercury is in orbit nearest the Sun.
Mercury, Venus, Earth, Mars and Pluto are not gaseous. Pluto is sometimes not regarded as a planet. Jupiter, Saturn, Uranus and Neptune are gaseous, although the latter two may have a solid core of frozen gas.
Earth is the largest rocky planet. After Earth is Venus, then Mars, and then the smallest, Mercury.
The mariner spacecraft explored Mercury, Mars, and Venus. The first successful space probe and first spacecraft visit to a planet was Mariner 2.
Mars is an inner planet, as is Mercury, Venus, and Earth.
Mercury is the closest planet to the Sun and has one planet[venus] between us[Earth] and Mercury.
The closest planet to mercury is Venus.
It can be sometimes, but Venus can be closer than Mercury ever can; Mercury is only the closest planet to Earth when Venus is on the opposite side of the Sun from Mercury and Earth, and maybe not even then (depending on exactly where Mars is).
None of the Mariners actually landed on Venus. They were "fly-by" missions. Mariner 2 reached Venus in December 1962 and Mariner 5 in 1967. In 1973, Mariner 10 passed Venus and used the planet's gravity to alter its course and continued on to Mercury.
Basically the answer is "Venus". Mariner 2 flew past Venus. Pioneer 5 explored the space between Earth and Venus.
No, Venus is
Venus
Mercury, Venus, Earth and Mars
venus
Mars, Earth, Venus, and Mercury.