The Biodynamic calendar references astronomy (not astrology) for the calculations, specifically constellations. What are constellations? Constellations are groups of stars. The constellations you can see at night depend on your location on Earth and the time of year. Astronomers use constellations to name stars and meteor showers. Maria Thun contributed over 40 years of research in Germany to establish the most favorable constellations for applying the attributes most desired to specific plants.
The Biodynamic calendar available from the Biodynamic Association contains the times (in New Zealand) of the main lunar, solar and other planetary events which affect sowing, planting and other farming and gardening activities. Information on how to use the calendar is provided in an additional 20 pages of notes and charts.
https://biodynamic.org.nz/shop
These are the fortnightly periods of the planting year where the moon is descending (perigee), moving closer to the earth and this enhances horticultural activity below the ground. For specific attributes during these periods refer to the biodynamic planting calendar sold by the NZ Biodynamic Association.
https://biodynamic.org.nz/shop