More than 80% of the universe is made of stuff we have never seen. These ghostly forms of energy and matter are only detectable by the effects they have on the stuff we can see. The invisible form of matter, called dark matter, makes up roughly 30% of the universe’s total mass. Its gravity drives normal matter (gas and dust) to collect and build up into stars, galaxies, and massive galaxy clusters. Although astronomers cannot see dark matter, they can detect its influence by observing how its gravity bends and distorts light from more-distant objects, a phenomenon called gravitational lensing.
![Lower left corner: Hubble sits looking toward the upper-right corner where there is a spiral galaxy. Between the two is an image of a large galaxy cluster. Lines drawn from the spiral at upper-right to Hubble illustrate the gravitational lens created by the galaxy cluster.](https://science.nasa.gov/wp-content/uploads/2023/04/macs_j1149-2223-jpg.webp?w=4096&format=png)
By looking at the area around massive galaxy clusters, which contain both normal and dark matter, astronomers can identify warped background galaxies gravitationally lensed by the cluster and reverse-engineer their distortions. Mathematical models of these results shed light on the location and properties of the densest concentrations of matter in the cluster, both visible (normal) and invisible (dark). The universe appears to have about five times more dark matter than regular matter, and its structure may center on an immense network of dark matter filaments that stretch between galaxies and grow over time. Areas where concentrations of these filaments intersect also hold massive visible structures like galaxy clusters.
![two Hubble images of galaxy cluster Cl 0024+17 (ZwCl 0024+1652), with right image shaded to illustrate dark matter](https://science.nasa.gov/wp-content/uploads/2023/04/galaxy-cluster-cl-0024-17-zwcl-0024-1652-jpg.webp?w=4096&format=png)
![A cluster of galaxies fills the frame. A purple glow around the largest concentrations of galaxies indicates the distribution of dark matter.](https://science.nasa.gov/wp-content/uploads/2021/12/hubble-abell1689-darkmatter-heic1014a-jpg.webp?w=4096&format=png)
Because these elusive filaments are so hard to find, astronomers have turned to similar forms on Earth for clues of where to look. A single-celled slime mold, called Physarum polycephalum, builds complex filamentary networks in search of food, finding near-optimal pathways to connect different locations. Astronomers using Hubble data designed a computer algorithm inspired by the slime mold’s behavior, to simulate the growth of dark matter filaments. The simulation resulted in a three-dimensional computer model of estimated locations of the cosmic web’s filamentary structure.
![Illustration: Purple filaments fill the view against a black background. They represent the growth of slime mold.](https://science.nasa.gov/wp-content/uploads/2023/04/stsci-h-p2011a-f-3531x2538-1.png?w=4096&format=png)
NASA's Goddard Space Flight Center; Lead Producer: Paul Morris
Hubble Focus: Dark Universe
Hubble Focus is a series of e-books that dive deeper into specific topics in astronomy that have been forever changed by Hubble’s explorations. "Hubble Focus: Dark Universe" is the fifth book in the series, highlighting the mission’s recent discoveries about dark matter and dark energy.
Read More and Download![](https://science.nasa.gov/wp-content/uploads/2024/04/hubble-focus-dark-universe-cover-v2.jpg?w=4096&format=jpeg)
Learn More
Hubble Detects Smallest Known Dark Matter Clumps
Using NASA's Hubble Space Telescope and a new observing technique, astronomers have found that dark matter forms much smaller clumps than previously known. This result confirms one of the fundamental predictions of the widely accepted "cold dark matter" theory.
Explore Other Hubble Science Highlights
Learn about some of Hubble's most exciting scientific discoveries.
![Cepheid star in Andromeda galaxy (Hubble observations)](https://science.nasa.gov/wp-content/uploads/2023/04/stsci-prc11-15a-jpg.webp?w=4096&format=png)
Discovering the Runaway Universe
Our cosmos is growing, and that expansion rate is accelerating.
![Hubble Ultra Deep Field image](https://science.nasa.gov/wp-content/uploads/2023/04/hubble_ultra_deep_field_stsci-prc04-07a-jpg.webp?w=4096&format=png)
Tracing the Growth of Galaxies
Hubble is instrumental in uncovering the various stages of galactic evolution.
![Hubble image left to right: Jupiter, Uranus, Saturn, Neptune](https://science.nasa.gov/wp-content/uploads/2023/04/hubble_opal_composite.png?w=4096&format=png)
Studying the Outer Planets and Moons
Hubble’s systematic observations chart the ever-changing environments of our solar system's giant planets and their moons.
![Hubble view of an expanding halo of light around star v838 monocerotis](https://science.nasa.gov/wp-content/uploads/2023/04/hubble-v838mon-heic0405a-jpg.webp?w=4096&format=png)
Seeing Light Echoes
Like ripples on a pond, pulses of light reverberate through cosmic clouds forming echoes of light.
![Hubble observations of galaxies' centers](https://science.nasa.gov/wp-content/uploads/2023/04/prc97-01-jpg.webp?w=4096&format=png)
Monster Black Holes are Everywhere
Supermassive black holes lie at the heart of nearly every galaxy.
![Hubble observations of Carina Nebula section](https://science.nasa.gov/wp-content/uploads/2023/04/eta-carinae-hubble20thpic-jpg.webp?w=4096&format=png)
Exploring the Birth of Stars
Hubble’s near-infrared instruments see through the gas and dust clouds surrounding newborn stars.
![An oval of colorful tendrils of gas and dust stretching from lower-left to upper right. Ova's outer ring is rusty-red tendrils, followed by a yellow/lime-green ring of tendrils. Oval's center is bright turquoise with white tendrils bisecting it. All set on a black background.](https://science.nasa.gov/wp-content/uploads/2023/04/hubble_crabnebula-jpg.webp?w=4096&format=png)
The Death Throws of Stars
From colliding neutron stars to exploding supernovae, Hubble reveals details of some of the mysteries surrounding the deaths of stars.
![Thirty proplyds in a 6 by 5 grid. Each one is unique. Some look like tadpoles, others like bright points in a cloudy disk.](https://science.nasa.gov/wp-content/uploads/2021/12/hubble-orion-proplyds-heic0917aa-jpg.webp?w=4096&format=png)
Finding Planetary Construction Zones
Hubble’s sensitivity can reveal great disks of gas and dust around stars.
![Three views of Pluto. Three mottled circles in colors of yellow, grey, rusty-orange, and black.](https://science.nasa.gov/wp-content/uploads/2023/01/hubble-pluto-stsci-01evsrjcapn1afkxej1d7e1njd.png?w=4096&format=png)
Uncovering Icy Objects in the Kuiper Belt
Hubble’s discoveries helped NASA plan the New Horizon spacecraft’s flyby of Pluto and beyond.
![Comma shaped curved cloud of gases in bright white edged with bright-pink star forming regions, and threaded with rusty-brown tendrils of dust at center and throughout the comma shaped merger. All set against the black of deep space.](https://science.nasa.gov/wp-content/uploads/2021/12/hubble-antennaegalaxies-potw1345a-jpg.webp?w=4096&format=png)
![Blue background. Center of image is a disk blocking the light of a star. Below and just to the left of the disk, at about seven o'clock, is a bright white point. This is PDS 70b.](https://science.nasa.gov/wp-content/uploads/2021/12/hubble-pds70b-stsci-h-p2121c-f-1280x1280-1-jpg.webp?w=4096&format=png)
Recognizing Worlds Beyond Our Sun
Hubble’s unique capabilities allow it to explore planetary systems around other stars.
![animation of a binary asteroid with a shifting tail](https://science.nasa.gov/wp-content/uploads/2023/04/comet3.gif?w=4096&format=png)
Tracking Evolution in the Asteroid Belt
These conglomerates of rock and ice may hold clues to the early solar system.