they are fairly close - http://en.wikipedia.org/wiki/Solar_system
Mercury
Mercury is the smallest and closest planet to the Sun in our solar system, while Mars is the fourth planet from the Sun, known for its reddish appearance. Mercury has no atmosphere and is extremely hot, while Mars has a thin atmosphere and is known for its surface features like canyons and volcanoes.
Must be hot as it is one planet closer to the Sun ... Mercury Venus Earth Mars etc.
the planet closest to the sun is Mercury
Mercury is the closest to the sun.
Mercury is closest to the Sun
yes
I know Mercury is the closest planet to the sun.
Mercury is closer to the sun than mars
First of all, Mars is a lot closer to Earth than Mercury. The other reason is that since it is further away from the sun, it is not as hot as mercury which makes it easier to send rovers.
Mainly because of the distance to the sun, which makes Mercury a lot warmer and Mars a fair bit colder. Mercury is too hot to have any running water, and Mars is too small to retain an atmosphere.