WHAT IS DARK MATTER?
Dark matter is the name scientists give
to matter that appears to have mass and
gravity but does not interact with
electromagnetic radiation in the way
ordinary matter does.
We cannot see it directly.
Instead, astronomers detect its
gravitational influence on galaxies,
galaxy clusters and the large-scale
structure of the Universe.
HOW DO WE KNOW IT EXISTS?
One major clue comes from galaxies.
Stars far from the centers of galaxies
often orbit much faster than expected
from the visible matter alone.
The simplest explanation is that a large
amount of additional invisible mass
surrounds the galaxy in a dark matter halo.
GRAVITATIONAL LENSING
Gravity bends the path of light.
By measuring how galaxies and galaxy
clusters distort the light from objects
behind them, astronomers can map the
distribution of unseen mass.
Gravitational lensing provides some of
the strongest evidence for dark matter.
DARK MATTER AND THE COSMIC WEB
Dark matter plays an important role in
the formation of cosmic structure.
Its gravity helped matter gather into
filaments, galaxy clusters and other
large-scale structures.
Ordinary matter then formed galaxies
within this gravitational framework.
HOW SCIENTISTS STUDY DARK MATTER
GALAXY ROTATION
The rotation speeds of galaxies reveal
more gravitational mass than can be
accounted for by visible stars and gas.
GRAVITATIONAL LENSING
Light from distant objects bends around
massive structures, allowing invisible
mass to be mapped.
GALAXY CLUSTERS
The motion of galaxies and the bending
of light around clusters indicate large
amounts of unseen mass.
COSMIC MICROWAVE BACKGROUND
The early Universe's radiation contains
patterns that help constrain the amount
and behavior of dark matter.
COSMIC STRUCTURE
Computer simulations reproduce the
large-scale Universe much better when
dark matter is included.
PARTICLE SEARCHES
Laboratories and underground detectors
continue searching for possible dark
matter particles.
DID YOU KNOW?
We can observe the gravitational effects
of dark matter across the Universe —
but scientists still do not know exactly
what dark matter is made of.
WHAT DARK MATTER EXPLAINS
Dark matter is a name for the unseen mass inferred from gravitational effects that ordinary visible matter alone does not adequately explain. Evidence comes from several independent observations, including the motions of stars and gas in galaxies, gravitational lensing, galaxy clusters and the large-scale structure of the Universe.
Its microscopic nature remains unknown. Leading research tests possible particles and alternative explanations while astronomical observations map where the additional gravitating mass appears to be distributed.
Galaxies · Dark Energy