From Astronomy to astrology.....

This article will help u understand the concept of positioning of planets in signs......

Astronomy- the study of heavenly bodies in the solar system & Astrology- the study of the effect of those heavenly bodies i.e., planets on the human beings on Earth.
As we know in our solar system all the nine planets revolve around the Sun(center of the solar system) ,but since man lives on the earth & in astrology we study effect of planets on human beings,we study the motion of planets with respect to Earth i.e., we take earth in center and measure position of bodies around it,including Sun,Moon and other planets. Likewise,as Earth revolves around the Sun in one year ,so in astrology we consider Sun revolves Earth in one year.
The imaginary path(line) along which the Sun moves is called ECLIPTIC.The broad band or belt extending 9 degree on either side of the ecliptic is known as ZODIAC.
This zodiac is divided into 12 equal parts of 30 degree each (making a total of 360 degrees). Each part is named as a sign like:- Aries,Taurus,Gemini,Cancer,Leo,Virgo,Libra,Scorpio,Sagittarius,Capricorn,Aquarius & Pisces.

Now to locate the position of planets from the Earth we use these signs.

now see from the figure:
The location of the planet is calculated by drawing a line from centre of Earth to the planet and the point at which this line cuts the Zodiac is said to be the position of the planet.
For example :if the line from the centre of the Earth cuts the zodiac at the point 100 degree 24' 20" which means
100 = (3x 30) + 10
thus,100 degree means 3 signs(that have passed) and 10 degree i.e.,100 degree=3 sign 10 degree
so we can altogether say that planet is in 4th sign at 10 degree 24 minute and 20 second..
so location of the planet is

3^s10^◦24’20”

similarly for other planets we can find out their respective position w.r.t the Earth