Mondo Knows Facts
Almost every galaxy is moving away from us
Their light is stretched toward red, and the further the galaxy the faster it recedes Edwin Hubble reported the relation between distance and redshift in 1929, evidence the universe expands. The stretching is not a Doppler shift through space but expansion of space itself. Measuring it yields the Hubble constant, still debated at the few per cent level. It sits in Mondo's space collection, one of 200 facts that each trace back to the reference below.
Where this comes from
Facts that can change over time are reviewed and updated. If something here looks wrong, Mondo would rather know than be confidently incorrect.
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More facts like this
The expansion of the universe is accelerating over cosmic timeDark energy pushes distant galaxies apart at ever-increasing speedsDark matter accounts for 85 percent of all matter in the universeInvisible matter exerts gravitational forces that hold galaxies togetherThe cosmic microwave background is the oldest light in the universeRelic radiation from 380,000 years after the Big Bang fills all spaceA teaspoon of neutron star matter weighs a billion tonnesThe material is compressed to the density of an atomic nucleusMost heavy elements were forged in starsCalcium in your bones and iron in your blood were made inside supernovaeThe lunar night falls to about minus 173 CelsiusWith no air to hold heat, the surface swings hundreds of degrees a day
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Tags: cosmology, redshift, expansion
Almost every galaxy is moving away from us: the short answers
- Where does this come from, and can I check it?
- Their light is stretched toward red, and the further the galaxy the faster it recedes. The figure is taken from NASA Science, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.
- Is this really a space fact?
- Yes. It sits on the Space shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.
- What else can I read about it?
- The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.