Astronomy, in general, is the study of celestial bodies, and the universe as a whole, excluding the earth. It includes the study of stars, planets, galaxies and other objects that are beyond the atmosphere of earth. The Bible does reference several objects, such as planets and constellations, found in what we today call space.
The sun is directly mentioned at least 160 times in the KJV translation, with the moon referred to 51 times. During Biblical times, the only planets viewable from the earth were Mercury, Venus, Mars, Jupiter and Saturn (The Biblical Basis for Modern Science, 2002, Chapter 6). Some of these can be found in Scripture, not by the names we call them today, but through the false gods associated with them.
References to Venus
Astronomy tells us that next to the sun and moon, the planet Venus is the brightest object we can see in the night sky. Its ability to reflect light is due to its close proximity to the sun and the highly reflective clouds of sulfuric acid that shroud it. Many times it can easily be seen just before sunrise, hence its reference as the "morning star." It can even be viewed during the day, lending to it also being called the "day star."
There are allusions in the Bible to Christ being the morning star. Since Venus was the brightest of all the points of light in the sky the analogy would be that Christ would be the brightest (or have the preeminence) over the other heavenly bodies, which are the stars that correspond to angels.
19. We also possess the confirmed prophetic Word . . . as to a light shining in a dark place, until the day dawns and the morning (the KJV has "day" instead of "morning") star arises in your hearts; (2Peter 1:19)
26. And to the one who overcomes . . . 28. And I (Jesus) will give him the morning star. (Revelation 2:26, 28)
I (Jesus) am the root and the offspring of David, the bright and morning star. (22:16)
References to Saturn
According to a 1913 Catholic Encyclopedia article titled "Astronomy in the Bible," the planet Saturn is directly referenced in the book of Amos.
"Saturn is no less certainly represented by the star Kaiwan (called "Chiun" in the KJV Bible), adored by the reprobate Israelites in the desert (Amos 5:26). The same word . . . frequently designates, in the Babylonian inscriptions, the slowest-moving planet."
In Stephen's discourse just before his martyrdom, he mentions God's condemnation of ancient Israel's idolatrous worship of "your god Remphan" (Acts 7:43). Remphan was the Egyptian name for Saturn (Jamieson, Fausset and Brown Commentary (JFB) on Amos 5:26), whom the Israelites continued to worship even after the Exodus.
Allusion to Jupiter and Venus
According to the JFB, Isaiah 65:11 alludes to Jupiter and Venus when God refers to gods linked with the planets.
11. But you who forsake the LORD, who forget My holy mountain, who prepare a table for Fortune (Hebrew Gad, the Babylonian god of fortune linked to Jupiter), and who furnish the drink offering to Fate (Hebrew Meni, linked with Venus)
Constellations and Star Clusters
The Bible contains several references to constellations or groupings of stars. The oldest writing of the Bible, Job (written around the 1660s B.C.) mentions astronomy-related phenomena more than any other book.
8. He alone stretches out the heavens, and walks on the waves of the sea; 9. Who made the Bear (Arcturus), Orion, and Pleiades (the "seven stars"), and the chambers of the south; (Job 9:8 - 9)
31. Can you bind the bands of the Pleiades, or loosen the cords of Orion? 32. Can you bring the constellations in their season? Or can you guide the Bear with its sons? . . . (Job 38:31 - 33, see also Amos 5:8)
The number of stars
"Look now toward the heavens and number the stars - if you are able to count them." (Genesis 15:5)
22. As the host of the heavens cannot be numbered, nor the sand of the sea measured . . . (Jeremiah 33:22)
How many stars does astronomy tell us exist? Do they truly number like grains of sand? The number of stars in the visible universe (not the entire universe) is currently estimated to be between 1022 to 1024 (1022 is 10 sextillion while 1024 is 1 septillion).
How big is the universe?
1. The heavens declare the glory of God, and the firmament proclaims His handiwork (Psalm 19:1)
How incredibly VAST is the universe? What astronomy calls the "observable universe" are those galaxies and other celestial objects whose light (and other signals) has had time since the Big Bang to reach the earth. This means, at the present time, it is estimated that we on earth can "observe" objects 46 to 47 BILLION light years away in any direction (this is greater than the age of the universe due to expansion). The entire universe itself, however, is much bigger! In fact, because the universe is expanding, with some distant regions speeding away from us FASTER than light, there are vast parts of God's creation that will never be "observable" from earth!
Alan Guth, creator of the theory of cosmic inflation, has approximated the total size of all that was created in the Big Bang. He calculates that it is 300,000,000,000,000,000,000,000 (300 sextillion or 3 followed by 23 zeros) times LARGER than the observable universe (The inflationary universe: the quest for a new theory of cosmic origins, pages 186)!
20. For the invisible things of Him are perceived from the creation of the world, being understood by the things that were made - both His eternal power and Godhead - so that they are without excuse; (Romans 1:20)
God, through astronomy in the Bible, has left mankind with no excuse regarding his awesome power. The heavens are a constant testament that He exists and that His power and wisdom are as limitless as the universe He created.