This is an astrological chart drawn up with the Sun on the cusp of the first house. It's used when there's no birth time, but some astrologers use a noon chart (set for 12 pm), to set the chart.Sun Sign 'Scopes
Sun sign horoscopes are often written with the solar chart in mind, with predictions based on transits to the solar houses. That's why you'll read that "Jupiter is transiting your 2nd House of Money and Values" -- the astrologer has set the wheel with your Sun sign at the horizon. Then general predictions are made based on the planets' placement in those houses.