This .NET class wraps the AcDbSun ObjectARX class. 

Sun class is a container for all properties relating to a sun object. A sun exists as a hard-owned child of an ViewportTableRecord or an AcDbViewport object. It is created when a sun-related operation is first performed (for example, changing a property on the Sun Properties Dialog or a sun-related parameter in the dashboard). It is also created when viewports are created by the sun study wizard. It is set and accessed by the APIs setSun() and sunId() defined on both viewport classes mentioned above. The properties defined in this class correspond to fields on the Sun property palette, but are also set and queried by other clients as mentioned earlier. 

Autodesk.AutoCAD.DatabaseServices.DBObject
    Autodesk.AutoCAD.DatabaseServices.Sun

Public Class Sun
Inherits DBObject

public class Sun : DBObject;