[The Clouds of Glory Say:]

Even when it is clear

He thickens clouds;

He spreads out His rain clouds.

(Iyov 37:11)

During the forty years in the wilderness, Yisrael  was protected and given light by the Clouds of Glory.  The Talmud teaches that they had no need for sunlight because the holiness of the clouds gave them all the light they needed.  Also, when the earth needs rain, G-d thickens the clouds with moisture and gladdens the dry earth.
[Tanach, Rabbi Scherman, Perek Shira]

[The Thick Clouds]

He made darkness His hiding place,

His pavilion round about Him -

darkness of water, thick clouds of the skies.

(Tehillim 18:12)

Darkness of waters means an accumulation of clouds; thick clouds of the skies means clouds that cover the sky.  "He made darkness His hiding place" alludes to the profound difficulty of knowing G-d, just as it is impossible to know what is inside a dark place.  For our material aspect keeps us separated from knowing the Almighty, but never despair, because G-d is always present, even when we can't see Him.
[MeAm Lo'ez, Perek Shira]

[The Stars Say:]

You alone are HaShem; You made the heavens,

the most exalted heavens and all their legion,

the earth and all that is upon it,

the seas and all that is in them,

and You give them all life;

and the heavenly legion bows to You.

(Nechemya 9:6)

A proclamation of G-d's infinite greatness, of His total mastery of every element of the universe. Almost every day, powerful telescopes see new suns, some of them bigger than the distance from our tiny planet to our little sun.  They see galaxies that dwarf ours, a constantly expanding universe.  And it all bows to the Master of the Heavenly legions!
[Tanach, Rabbi Scherman, Perek Shira]

[The Moon Says:]

He made the moon for festivals,

the sun knows its setting.

(Tehillim 104:19)

G-d created the moon to be the basis of our calendar, the timeline of the Festivals.  The moon does not have its own light, it shines in conjunction with the sun.  But "the sun knows it setting."  Its rising and setting are fixed because it shines by its own light.  The waning and waxing of the moonlight symbolizes human life.  Until his middle years, a person continues to increase, thereafter he continues to decrease, until he reaches the appointed place of all living things.
[MeAm Lo'ez, Perek Shira]

[The Sun Says:]

The sun and moon stood still in their abodes,

[Yisrael] would travel by the light of Your arrows,

by the brightness of Your gleaming spear.

(Chavakkuk 3:11)

The sun is a symbol of respect for G-d and generosity to others.  Arrows and the spear of G-d is lightning bolts.  HaShem cast lightning bolts and hailstones upon Yisrael's enemies, who fled before the B'nei Yisrael.  Both the sun and the moon are mentioned, yet in the singular form of "stood" is stated.  In the future, the sun and moon will enjoy the same stature.  The Chazal teach that they will shine with equal brightness, just as they did at the time of their creation.
[MeAm Lo'ez, Perek Shira]