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MISSING DARK MATTER HUBBLE MYSTERY

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Dark matter is the invisible glue
that holds the universe together.

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"Galaxy Motion Simulation. Observed with Dark Matter (On left) and Predicted without Dark Matter (On Right.)"

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Most galaxies are rotating so fast that gravity
generated by stars and gas alone can’t keep them together.

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They should have flown apart long ago.
Something we can’t see must glue them together: dark matter.

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Unlike observable matter, dark matter does not emit,
absorb, or reflect light, making it hard to detect.

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Instead, astronomers look for the
gravity signature of dark matter by
observing its effects on galaxies.

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In 2018, galaxy NGC 1052-DF2 made headlines
because it seemed to be missing dark matter.

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The observed number of stars in NGC 1052-DF2
accounted for most of the gravity.

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This unique galaxy contains a tiny fraction
of the dark matter astronomers expected.

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A galaxy lacking dark matter is an extraordinary
claim. It upsets theories of galaxy formation and evolution.

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Because this result was so unusual,
some astronomers questioned it.

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They looked for other explanations.
Could the galaxy be closer, and have fewer stars
than its brightness suggested?

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It would also imply the galaxy had more dark matter,
to balance the insufficient gravity due to fewer stars.

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In theory, if two galaxies are the same distance away,
their brightness would differ from each other.

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But if the galaxy with fewer stars is brought closer…

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...both galaxies would appear to be the same brightness.

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Hubble collected more data to
better measure the galaxy’s distance.

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The team targeted aging red stars whose
peak brightness is used to determine distance.

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But the new Hubble measurements still found
it was a distant galaxy as originally suspected.

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The mystery of why NGC 1052-DF2 is
missing most of its dark matter still persists.

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[SILENCE]