You can find the Sun and Moon on a birth chart. Where is Earth? In a typical chart, Earth is where you look from.
Earth is the viewing point
A birth chart is set for a time and place on Earth. It marks the positions of the Sun, Moon and planets as seen from that perspective. Earth is the starting point for the picture, so it usually has no separate mark around the wheel.
A viewpoint is not an orbit
Earth orbits the Sun. Drawing a chart from Earth does not mean the Sun circles a motionless Earth. It only sets the place from which the positions are described.
Use the center as a clue
When you look at the symbols around the wheel, think of its center as your viewpoint. The chart is a way to arrange directions from Earth, not a scale model of the solar system.
A few common questions
If Earth is not marked, does my birthplace matter?
Yes. A birth chart uses the birth time and place to set its local horizon and houses.
Sources & further reading
Astrology sources describe their own traditions and methods; they do not establish predictive accuracy. The writing exercises are original Lodestar editorial material.