We all know about the horoscope thing, in where we just determine what our sign is. However, sometimes some of the characteristics don't match yourselves (I've been there before). Surprisingly, if you go deeper into horoscope, there's more than just range of 'birth dates'. There are decans(got info from a friend), cusps, planetary signs, and charts( I'm not going into too much details on charts, 'cause I myself haven't studied on those)
First off, there are planetary signs in horoscope, and yes, the solar system is related, especially the sun. 
Planetary signs
Sun, the center of the solar system, giving light to planets orbiting it. The sun, in horoscope, shows your true nature, uniqueness, and ego.
Moon determines a person's mood and emotions
Mercury governs in how well we use our mind, such as; language, communication, etc.
Venus plays a role in love life and beauty.
Mars determines the energy, aggressiveness, and impulsiveness.
Jupiter, best known as planet of luck, determines our luck, opportunity in life, and also optimism.
Saturn will determine how much we learn in life by giving obstacles for us to pass through, increasing our endurance and patience.
Uranus which means change. It deals with changes and rebel characteristics.
Neptune deals with illusion, imagination, deception, spiritual and pyschic forces.
Pluto, in horoscope which means depth, deals with unconsciousness, birth, death, and secrets.

For starters, planets might be quite confusing, but they're going to be used in charts and determining characteristics. Besides, there are more than just planets, extra ones include asteroids and inclusion of Rising Sign (Ascendant), Midheavens, etc.
I'm going to continue this weekly, but for the first two, I might be kind of busy due to exams. Thanks for reading, if you want to speed things up, you could click on the site below and learn a bit more, because what I'm sharing is just the simple ones.
http://www.cafeastrology.com/articles/planetsinastrology.html