【Question 10】The polyhedron shown in the figure is called a regular icosahedron, one of the 5 Platonic solids (regular polyhedra). This polyhedron is formed by 20 faces (equilateral triangles). Now, these 20 faces are to be colored, with the requirement that two faces sharing an edge must be colored differently. Then, at least $\qquad$ colors are needed.
Analysis: Each vertex is connected to 5 faces, and the 5 faces around this vertex require at least 3 colors to ensure that two faces sharing a common edge are colored differently. Therefore, to color these 20 faces such that two faces sharing a common edge are colored differently, at least 3 colors are needed.