The universe is mostly made of invisible stuff: about 68% dark energy, 27% dark matter, and only around 5% ordinary matter like atoms, stars, planets, and people.

Quick Scoop: What Makes Up the Universe?

Think of the universe as a cosmic “budget” of energy and matter.

  • About 68% is dark energy, a mysterious form of energy that seems to push space itself to expand faster and faster.
  • Around 27% is dark matter, an invisible kind of matter that doesn’t emit light but has gravity and helps hold galaxies together.
  • Roughly 5% is ordinary matter: atoms that form stars, planets, gas, dust, your body, and everything we can see directly.

Within that small 5%:

  • Hydrogen is the most common element in the universe, followed by helium; together, they make up nearly all ordinary matter by number of atoms.
  • Heavier elements (carbon, oxygen, iron, etc.) are a tiny fraction, forged inside stars and in stellar explosions over billions of years.

So when we ask “what makes up the universe,” most of the answer is actually things we can’t see directly , inferred from their gravitational effects and from how the universe expands over time.

Ordinary Matter: The Stuff We Know

Ordinary matter is built from atoms, which themselves are made of protons, neutrons, and electrons.

  • Protons and neutrons are made of quarks, bound together by the strong nuclear force.
  • Electrons are a type of lepton that orbit atomic nuclei and control chemistry.

Key points:

  • Most visible matter in space is hydrogen and helium gas, plus stars made largely of these elements.
  • Stars, planets, and galaxies that we see are only a small slice of all ordinary matter; even much of that 5% is in forms that are dim or hard to detect, like diffuse gas.

Example: The Sun is mostly hydrogen and helium, but your body is mostly made of heavier elements like carbon, oxygen, nitrogen, and calcium that were produced in earlier generations of stars.

Dark Matter: The Invisible Glue

Dark matter does not emit, absorb, or reflect light, but it has mass and exerts gravity.

Evidence it exists:

  • Galaxies rotate faster than they should if only visible matter were present; extra unseen mass must be providing extra gravity.
  • Light from distant objects bends as it passes massive regions where there is not enough visible matter to account for the effect (gravitational lensing).

Cosmological measurements suggest:

  • Around a quarter of the universe’s total mass–energy density is dark matter.

We still don’t know what dark matter is made of, but many theories propose new particles beyond the known ones in the Standard Model of particle physics.

Dark Energy: The Cosmic Accelerator

Dark energy is the name given to whatever is causing the expansion of the universe to speed up rather than slow down.

Observations behind this idea:

  • Distant supernovae appear dimmer (and therefore farther away) than they would in a universe whose expansion is slowing, implying acceleration.
  • When combined with measurements of the cosmic microwave background and galaxy clustering, the data point to a dominant smooth energy component filling space.

Dark energy makes up about 68% of the universe’s mass–energy density.

One leading idea is that it could be a “cosmological constant” — an energy associated with empty space itself — but its true nature remains unknown.

Other Tiny Components

Besides the big three (ordinary matter, dark matter, dark energy), there are smaller but interesting contributors.

  • Neutrinos: Extremely light, weakly interacting particles that stream through the universe; they contribute less than about 0.3% of the total mass–energy.
  • Electromagnetic radiation: All the light and other radiation (from radio waves to gamma rays) adds up to roughly 0.005% of the total.

Though they are a tiny fraction of the “budget,” these components are crucial for how we observe and understand the universe.

Composition Snapshot (Mass–Energy of the Universe)

Below is a simple breakdown of what makes up the universe today, in terms of mass–energy density.

[9][5][6][7] [5][6][9][7] [6][9][5][7] [9][5][6][7] [1][3][5][9][7] [3][1][7] [7] [7] [7] [7]
Component Approximate share Key role
Dark energy ≈ 68%Drives accelerated expansion of the universe
Dark matter ≈ 27%Provides extra gravity, shaping galaxies and large- scale structure
Ordinary matter (atoms) ≈ 5%Forms stars, planets, gas, dust, and living things
Neutrinos < 0.3%Very light particles, rarely interacting with matter
Electromagnetic radiation ≈ 0.005%All light and radiation, including the cosmic microwave background

How People Online Talk About It (Forum-Flavored View)

On public forums and science discussions across the internet, you’ll often see a few recurring themes when people ask “what makes up the universe.”

“It blows my mind that everything we see is just 5% of what’s really out there.”

Common viewpoints and questions:

  1. “We are mostly dark stuff we can’t see”
    • Users point out that galaxies, stars, and planets are just the tip of the cosmic iceberg.
 * They often share infographics showing the 68–27–5 split to highlight how dominant dark sectors are.
  1. “Dark matter vs. dark energy — what’s the difference?”
    • Dark matter: pulls things together with gravity.
 * Dark energy: pushes space apart, driving acceleration.
  1. “Are we sure about these percentages?”
    • People often discuss how measurements of the cosmic microwave background, galaxy surveys, and supernovae combine to give those numbers, emphasizing they are model-dependent but strongly supported.
  1. “What’s the latest news?”
    • Recent years’ “latest” updates are less about changing the basic percentages and more about tightening error bars and testing different models for dark energy and dark matter.

Story Snapshot: A 3-Layer Universe

A popular storytelling way to picture this is as a three-layer cake of reality:

  1. Top layer: Ordinary matter — bright frosting
    • This is everything your eyes and telescopes see: stars, galaxies, nebulae, planets.
  1. Middle layer: Dark matter — invisible sponge
    • You don’t see it directly, but it gives the cake structure and holds it together; galaxies sit inside dark matter “halos.”
  1. Bottom layer: Dark energy — the expanding plate
    • The plate underneath is growing, stretching everything on top farther apart with time.

This kind of story shows up a lot in science explainers and online discussions because it captures both the familiarity of ordinary matter and the mystery of the dark components.

Brief TL;DR

  • The universe is mostly dark energy (≈ 68%) and dark matter (≈ 27%), with only about 5% ordinary matter like atoms.
  • Ordinary matter is largely hydrogen and helium, plus a small amount of heavier elements made in stars.
  • Dark matter pulls galaxies together; dark energy drives the accelerated expansion of space.

Information gathered from public forums or data available on the internet and portrayed here.