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Dark Matter & Dark Energy – Cosmology · The great mystery
Image: NASA, ESA, D. Coe (NASA Jet Propulsion Laboratory/California Institute of Techno · CC BY 4.0
💥 Cosmology · The Whole Universe

Dark Matter & Dark Energy

Cosmology · The great mystery

Everything we can see – stars, planets, people – is only about 5% of the universe. The rest is dark matter, invisible stuff that pulls on galaxies with its gravity, and dark energy, which is making the expansion of the universe speed up. Nobody yet knows what either of them is.

  • 3.7 billion light-years awayEven light – the fastest thing there is – needs 3.7 billion years to get here.
  • ~5%Ordinary matter
  • ~27%Dark matter
🔭 Find it in the sky (Bullet Cluster)

Take a closer look

Not Made of Atoms

Dark matter doesn’t shine, reflect or block light, and it isn’t made of ordinary atoms. There is roughly five times more of it than all the normal matter in the universe. Without its extra gravity, gas in the young universe may never have clumped into galaxies like ours.

Gravity’s Magnifying Glass

Dark matter’s gravity bends light from more distant galaxies, a bit like the bottom of a glass bends the view of things behind it. By measuring how background galaxies are stretched and distorted, astronomers draw maps of where the invisible dark matter must be.

Hunting Deep Underground

Some dark matter detectors sit in old mines more than a kilometre underground, where rock shields them from cosmic rays. Giant tanks of cold liquid xenon wait for a dark matter particle to bump into an atom. So far, none has been caught – the hunt continues.

How we found out

  1. 1933

    Fritz Zwicky sees galaxies in the Coma Cluster moving too fast and suggests “dark matter” holds them together.

  2. 1970s

    Vera Rubin and Kent Ford show that the outer parts of galaxies spin too fast – strong evidence for dark matter.

  3. 1998

    Two teams discover that the universe’s expansion is speeding up – dark energy. (Nobel Prize 2011.)

  4. 2006

    The Bullet Cluster – two colliding galaxy clusters – shows dark matter separated from ordinary matter.

  5. 2024–25

    The DESI survey finds hints that dark energy might be changing over time. The Euclid telescope and the Vera C. Rubin Observatory are now mapping the dark universe.

🤔 Something to wonder about

Could the next big discovery be yours?

See it yourself

The phone points to the Bullet Cluster, about 3.7 billion light-years away, where dark matter was “seen” through its gravity.

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