We call it the universe, but even that word feels too small. The observable universe is the universe we can see through telescopes. However, the greater the distance astronomers observe, the farther back in time they see. This lookback time is a consequence of the velocity of light.
For example, when astronomers observe the Sun, they don’t see it as it is now, but what it was about 8 minutes ago since it took light from the Sun 8 minutes to travel to Earth. Similarly, when astronomers observe the Andromeda Galaxy, they see it as it was 2.5 million years ago since it is at a distance of 2.5 million light years.
Since the universe is only 13.8 billion years old, the most distant observable objects are 13.8 billion light years away. However, the universe has been continuously expanding ever since the cosmic creation event. Hence, the universe that exists today is much larger than the universe astronomers can detect through their telescopes. Based on the measured cosmic expansion rate, astronomers have determined that the presently existing universe is at least 93 billion light-years across.
At RTB, our astrophysicists study the universe’s mass, size, and designs, revealing just how immense and finely tuned it truly is. Let’s explore what science can observe and what Scripture helps us understand. Together, they reveal not only the scale of the cosmos in miles and light-years, but also the intentionality behind it. They reveal that the universe didn’t happen by chance. Its precisely fine-tuned mass, size, and designs remind us of God’s magnitude and power—and of how much more exists beyond what our minds can comprehend.
What Is the Size of the Universe?
To say that the universe for most people is unimaginably big is no exaggeration. Nevertheless, the universe’s size can be visualized. The universe astronomers can see through their telescopes contains about 2 trillion galaxies. Galaxies on average contain about 50 billion stars. That adds up to a hundred billion trillion stars in the observable universe.
How big are the stars? They range in size from 6 miles to a billion miles in diameter. The Sun is a medium-sized star with a diameter of 865,000 miles. One way to visualize the Sun’s size is that one could pack 1.3 million Earths inside the Sun. One way to visualize the largest stars is that one could pack 1.5 billion Suns inside the largest star!
We live in a large spiral galaxy. Our galaxy’s spiral disk contains an estimated 200 billion stars. Our galaxy is orbited by 152 globular clusters. The smallest such globular cluster contains about 50,000 stars. The largest contains about 10 million stars. The giant galaxy M87 in the nearby Virgo Cluster of galaxies has 17,000 globular clusters orbiting it. The largest known galaxy is a thousand times more massive than our Milky Way Galaxy, which weighs 1.2 trillion times the Sun’s mass.
How far apart are the stars from one another? If one were to scale our Sun down to the size of a grapefruit and place it at Terminal 1 of the Los Angeles International Airport, the nearest other grapefruit (star) would be in Peru.
How big is the universe? The observable universe contains a hundred billion trillion stars where the stars are separated from one another by an average of about 25 trillion miles. See this video for a visual treat showing how big is the universe.
And yet, what we see is not all there is. The stuff we see through our telescopes, the stars, planets, nebulae, and galaxies, comprises just 0.27% of the universe. Most of the universe, the other 99.73%, is made up of dark stuff.
The total quantity of stuff in the universe, as incredibly massive and big as it is, cannot be any smaller or any larger for life to possibly exist in the universe. Make the universe the tiniest bit smaller, no elements heavier than helium would exist. Make the universe the tiniest bit bigger, no elements lighter than iron would exist. In both cases the universe would contain no carbon, no nitrogen, and no oxygen and physical life would be impossible.
Evidently, the Creator of the universe did not think it too costly to create a vast universe and carefully and exquisitely fine-tune it for 13.8 billion years so that human beings could live and thrive on a beautifully designed planet. How great is the Creator’s love for us that we see manifested in the size, mass, and designs of the universe!
How Do We Measure the Size of the Universe?
We measure the universe through light emitted by its galaxies, stars, nebulae, gas, and dust.
Astronomers trace light across the ages, following its path through space to learn how the universe has changed over time.
They use methods with names that sound almost poetic—like parallax, redshift, and standard candles—but each one is rooted in careful measurement. Together, these tools help translate the majesty of creation into data we can study and understand.
Every beam of light carries information about where it came from and what it’s passed through, a record of the universe’s history written in photons.
And the more carefully we measure, the more awe we uncover. Every beam of light reveals the physical state of the cosmic object that emitted it and the precise values of the laws and constants of physics at that cosmic site and that cosmic time. Every light beam reflects the faithfulness of the Creator.
Science calls it testable, measurable, and reliable. Faith calls it design.
The Expansion of the Universe: The Sky That’s Still Stretching
We’ve learned something else from that ancient light: the universe isn’t static.
It’s alive with motion and growth—unfolding and stretching toward horizons we have yet to see.
From the first spark of creation, space itself has been expanding.
Every galaxy became a traveler, drifting outward on a tide that has never ceased.
Astronomers can see it even now: galaxies slipping away in every direction, their light stretched thin into longer, redder wavelengths, like a song deepening as it echoes through time.From the beginning, God designed a universe that expands, a scientific concept consistent with Scripture’s description of him “stretching out the heavens.”
And yet, the same God who sent the galaxies expanding away from one another also holds them fast. Gravity gathers stars into clusters, planets into orbits, and atoms into being. As physicists study these phenomena, they see incredible cosmic fine-tuning, a precise balance of forces that lets stars burn, atoms bond, and galaxies hold their form.
Physics reveals a sophisticated dance between forces that hold them together and ones that pull them apart. The expanding universe is governed not by chaos, but care.
Distant galaxies race away from us faster than nearby galaxies. This observed phenomenon is the predicted outcome of the entire universe undergoing a nearly constant rate of expansion. Just like dots on an expanding balloon that are farther apart than dots that are closer together appear to move away from one another at a faster rate, so too the greater a galaxy’s distance from us the faster it moves away from us.
Astronomers call it continuous expansion.
Scripture says the Lord “stretches out the heavens like a canopy, and spreads them out like a tent to live in” (Isaiah 40:22).
Different words. Same truth.
Astronomers’ measurements of the cosmic expansion rate reveal that the expansion rate is gradually accelerating. This acceleration implies that some time in the future the most distant galaxies will be moving away from us at speeds greater than the velocity of light. When that happens, these galaxies will cease to be visible to us. One day, the galaxies’ light will drift beyond our sight, not because the light has died, but because the space between has stretched too wide for it to reach us.
Is the Universe Infinite in Size?
Stay under the stars for a while, and you’ll start to wonder—does this ever end?
Astronomers have mapped the observable universe, limited by how far light can travel since the beginning.
Beyond that? We can only imagine.
Some have even proposed that our universe may be one of many, a multiverse, a vast ensemble of realities beyond our reach.
Even if physical realms exist beyond the observable universe, physicists expect them to follow the same physical laws, constants, and patterns as the universe we can see. This idea—known as the cosmological principle—assumes that the universe is uniform and governed by the same laws everywhere, not just in our corner of the cosmos. Indeed, everywhere we can make measurements, we see that the laws and constants of physics measure to be exactly the same as they are on Earth.
That consistency points to the reliability and order built into creation by its Designer.
The size of the observable universe is something we can accurately measure. The fine-tuned features of the universe reveal its order, wonder, and at least eleven distinct purposes or reasons why the universe is the way it is.
How Big Is the Universe?
The size of the universe reminds us just how small we are and how immense the One who designed it must be.
Isaiah wrote that God measures the heavens “with the breadth of his hand” (Isaiah 40:12). What ancient Scripture expresses, modern astronomy confirms scientifically: the heavens are vast, measurable but beyond our ability to comprehend, and governed by precise physical laws.
Every advance in observation, each new telescope, each new image of distant galaxies doesn’t diminish mystery, it deepens it. The more we discover, the more evidence we see of order, stability, and fine-tuning throughout all of creation.
How big is the universe, really?
Big enough to silence pride.
Small enough to rest within the reach and control of its Creator.
The story the 2 trillion galaxies and a hundred billion trillion stars are telling isn’t about how far they extend, but how faithfully God reigns.
The Shape of the Universe
Astronomers have measured the universe’s size, age, and expansion with remarkable precision, but its overall shape remains one of cosmology’s most fascinating questions.
Current evidence from satellite missions such as WMAP and Planck suggests that the universe is flat on large scales. In a flat universe, light travels in straight lines rather than curving back on itself. This means that, within the portion of the cosmos we can observe, parallel lines would never meet.
However, beyond the limits of our observation, the question is still open.
Some scientists have theorized that the universe is curved like a sphere—a “closed” model—where light could, in theory, circle all the way around and return from behind its starting point, like a traveler who leaves home and arrives again from the opposite direction.
Others suggest it may be that its shape is like a saddle, an “open” model bending ever outward, a universe that never meets itself again.
While we don’t yet have enough data to determine the universe’s exact geometry, the evidence we do have shows extraordinary consistency. The same fine-tuning that governs its forces and constants appears to extend to its shape. The order we observe in the universe’s geometry reflects the character of the One who established its laws—a God of balance, harmony, and design.
How Large Is the Universe?
When astronomers talk about how large the universe is, those discussions not only describe its scale but must also include the remarkable reliability of how the universe behaves. Immensity and intricacy coexist; the same physics that govern entire galaxies also govern the atoms in our own bodies.
Isaiah 40:26 and Psalm 147:4 state that God has given a name to every star and knows the name of every star. If he knows the name of every star, he certainly knows our name. If he cares for every star, he certainly must care immensely more for every human being. As Jesus said, “Indeed, the very hairs of your head are all numbered” (Luke 12:7). The same God who governs galaxies also knows every detail of the world and of each life within it.
Does the Universe End?
Astronomers have long studied what the distant future of the universe might hold. One of the most widely accepted scientific models is known as the Big Freeze or the Heat Death of the Universe. In such a universe, hot bodies will get colder and cold bodies will get warmer. Eventually, every body, every speck of dust, every gas molecule and every atom will attain the identical temperature. When that happens heat will cease to flow in the universe. Work will become impossible. Life will become impossible.
Scripture, however, reveals that what looks like a depressing, hopeless ending is really a transition. God is using the present physics of the universe to eradicate sin and evil. The apostle John describes a future “new heaven and a new earth” (Revelation 21:1), and Paul wrote that what is sown perishable will be raised imperishable (1 Corinthians 15:42–44). In other words, creation is not destined for extinction but for renewal. The moment God completely eradicates evil and finishes his work of redeeming willing humans from their sin, he will replace the universe with the new creation, a realm with radically different physics and different dimensions, a realm where God will reward his followers with blessing far beyond what they can imagine (1 Corinthians 2:9).
The same God who stretched out the heavens will bring his creation to completion, demonstrating that nothing, not even the cosmos itself, lies beyond his redemptive plan.
Bigger Than the Universe: The God Who Cannot Be Contained
If creation stretches across billions of years, trillions of galaxies, and miles beyond measure, then the question remains: What could possibly be bigger than the universe?
We can see the stage.
But who wrote the play?
Who drew back the curtain of space and time?
No constellation of laws or particles can explain that first spark.
Everything within the universe depends on something beyond it.
Even skeptical scientists agree on this much: whatever ignited our universe can’t be part of it. It must exist outside our space and time altogether.
Scripture says it plainly: “By faith we understand that the universe was formed at God’s command, so that what is seen was not made out of what was visible” (Hebrews 11:3).
Because God is beyond, he isn’t bound by decay or change.
He holds the universe by his power; never shaped by it, but shaping all that is.
If the universe is vast beyond imagination, what’s greater is the One who says, “I am the Alpha and the Omega, the First and the Last, the Beginning and the End” (Revelation 22:13).
If cosmic distances leave us speechless, bigger still is the love that spans them.
If galaxies fade and worlds dissolve, bigger still is the hope that will never end.
Where the Vastness of Space Meets the Nearness of God
Every question we ask about the heavens eventually points back to its Author. We can measure galaxies, chart their motion, and trace light that began billions of years ago. Yet, at the edge of every discovery, the same realization awaits: there is more.
Science reveals how the universe works. Faith reveals why it exists.
Science reveals how the universe works. Faith reveals why it exists.
The more we learn about creation, the more clearly we see multiple purposes woven into its structure. Every constant, every law of physics, every beam of light reflects intention rather than accident. The universe operates with precision that invites not only study, but also worship of the One who brought it into being.
And yet, the greatest wonder is not merely that God created such an expansive cosmos, it’s that he entered it.
The Creator who set galaxies in motion also stepped into human history. The Word who spoke light into existence became the Light of the world.
That truth reframes every discovery. The universe doesn’t point us away from God; it draws us toward him. Each observation deepens our understanding of his power and our gratitude for his presence.
If you’d like to explore further, you can find more insights in our resource library—or dive deeper through Dr. Hugh Ross’s book, Why the Universe Is the Way It Is, a look at how the cosmos reveals the wisdom and purposes of its Creator.
Because in the end, every light-year, every law, and every living soul testifies to one truth:
The universe was made on purpose, by a God who hung the galaxies in place and still holds us close to his heart.
