Astrophel and Stella (now called Astrophil and Stella), which includes 108 sonnets and 11 songs, is the first in a long line of Elizabethan sonnet cycles. "Sonnet cycles" were so named because they incorporated linked sonnets that generally described the progressive rise and fall of a love relationship. In other words, through a number of distinct but related poems, it was possible to infer a plot. Most of the sonnets in Astrophel and Stella are influenced by Petrarchan conventions, incorporating traditional methods such as addressing the moon and the world of sleep and dreams, mourning the lady's absence, praising her unique beauty, bemoaning her coldness, and highlighting the lover's frustrated longings. Like Petrarch's poems, Sidney's work displays a variation of emotion from sonnet to sonnet within the trappings of a vague but thematic narrative. Sidney's experiments with rhyme scheme in his sonnets also were deeply significant for English Renaissance poetry, essentially freeing the English sonnet from the inflexible rhyming requirements of the Italian sonnet form.
Though the poems circulated widely in manuscript form, an official edition was not printed until 1591, five years after Sidney's death. This text, however, was considered to be inaccurate, and the most authoritative version came from a 1598 folio of Sidney's Arcadia, which contained an edition of Astrophel and Stella. This folio was supervised directly by Sidney's sister.
Sidney's sonnet sequence also exhibits clear references to Homeric epic, particularly Homer's Penelope. Some scholars have suggested that the 108 sonnets in the sequence represent the 108 suitors of Penelope, who play a game of striving to hit the Penelope stone in order to determine who can court her. The 119 poems are also just one number short of the number of months Ulysses spent trying to return home to Penelope in The Odyssey. The structure of the sonnet sequence, falling one month short of achieving Ulysses's journey home, can be seen as an emphasis on Sidney's failure in his pursuit of his own Penelope.
It is generally accepted that the Stella of the poems is Penelope Devereux, later Lady Rich, and that Astrophel (Astrophil) is Sidney himself. Critics disagree, however, on whether Sidney's love for Penelope is real or merely literary, meant simply to emulate the style of Petrarch's poetic adoration of "Laura." Because neither Elizabethan historians nor Sidney's own early biographers gave any clear account of his relationship with the Stella of the poems, the sonnets themselves are the only key to contextualizing the poetry with his romantic life.
The impossibility of a successful relationship between the two is a key theme of the sequence. The rift between the two is also expressed in the title of the piece. First of all, the title is made up of one name of Greek origin and one name of Latin origin: a clear disjunction. The presence of the grammatical copula "and" suggests that the two are a couple (such as "Tristan and Isolde" or "Romeo and Juliet"), which readers immediately realize is not the case. Even the names themselves, meaning "star-lover" and "star," describes a separation between the two: there will always be distance between the stars and those who love them.