Starry, stellar, astral, sidereal can mean of, referring to, or suggestive of a star or group of stars.
Starry is the ordinary nontechnical term, capable of being used in reference to stars of various kinds (as the celestial bodies known as stars or the geometrical figure with five, six, or more points that is the conventionalized star).
Stellar has the same range of reference as starry, but, since the connotations of the words are not the same, they are rarely interchangeable; starry gathers its connotations (as of brilliancy, remoteness, and beauty) chiefly from the appearance of the celestial stars to the ordinary observer; stellar derives its suggestions chiefly from astrological lore of the stars as influencing all things and as shaping human destinies or from astronomical knowledge of the constitution, arrangement, and classification of stars; thus, one tends to speak of a stellar, rather than a starry, influence or aspect; of a stellar, rather than starry, eclipse or nebula.
Stellar is also used more often than starry of theatrical or cinematic stars and it alone is freely used to imply outstanding quality or position in other relations.
Astral is in much of its use a technical term in theosophy and similar cults, and in more general use it is likely to bear connotations of spirituality, mysticism, and remoteness from the fleshly that derive largely from mythological and other conceptions of the stars as the abode of celestial spirits or of supersensible beings whose nature and constitution are rarer and finer than those of earthly human beings.
Sidereal is sometimes interchangeable with the other terms, but distinctively it is used in opposition to solar, especially as applied to periods of time measured by the rotation of the earth with reference to a given star; thus, the sidereal day , determined by reference to Aries, is 3 minutes and 55.91 seconds shorter, as measured in solar time, than the mean solar day.