Planets can be in any sign or house. They are expressed most powerfully in their own sign, and or own house. Therefore I am taking you on a journey around the zodiac, from the first house to the 12th, to offer an image of where the planets ‘were born,’ and where they powerfully express.
Example of Mars: It can be anywhere in the chart, but if it’s placed in the first, no matter the sign it’s in, it will display with greater Martian energies. If Mars is in the 10th, no matter the sign, there will be an underlying 10 house Capricorn energy which Mars will use to express its desire to rise to the top. You add that knowledge to the sign it’s in and you begin to have a richly layered tapestry of information.