What do the sun and moon symbolize in Romeo and Juliet?

Shakespeare plays with images of light and
darkness throughout ; indeed, many of the scenes happen either late at
night or early in the morning. In act 2, scene 2, however,provides some of the most famous lines
in all of English literature:

But, soft! What
light through yonder window breaks?
It is the east, andis the sun.
Arise, fair
sun, and kill the envious moon,
Who is already sick and pale with grief.
(II.ii.44-47)

In these lines, Romeo compares
Juliet to the sun. This is after the Capulet party, and Romeo is awaiting a glimpse of his
beloved as he waits below her balcony. It is dark, late at night, and Romeo believes that
Juliet's beauty is enough to transform the night into day, much like a sunrise.

It's also important to remember that Romeo has been through his own symbolic
"night" recently over Rosaline's rejection. In fact, just before this party,has to
persuade Romeo to even attend, telling him to "Compare her face with some that I show,/ And
I will make thee think thy swan a crow" (I.ii.87-88). It could also be argued that Rosaline
is the darkness that has encapsulated Romeo's heart, and Juliet is the sun that breaks through
that darkness with her beauty.

Romeo goes on to ask Juliet to appear at her
window ("Arise, fair sun...") and "kill the envious moon." Here, the moon
symbolizes the passions Romeo held before, whose light and beauty pale in comparison to the
bright and beautiful Juliet. Romeo realizes that anything he considered love before beholding
(and kissing) Juliet is inconsequential.