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Explanation: Only a few short years ago, when the APOD editors were in graduate school, the pervasive, cosmic Dark Energy was not even seriously discussed. Of course, it now appears that this strange energy dominates the cosmos (as well as lectures on cosmology) and provides a repulsive force accelerating the large scale expansion of the Universe. In fact, recent brightness measurements of distant and therefore ancient, stellar explosions or supernovae indicate that the universal expansion began to speed up in earnest four to six billion years ago, when the Dark Energy's repulse force began to overcome the attractive force of gravity over cosmic distances. The Hubble Space telescope images above show a sample of the distant supernova explosions, billions of light-years away, in before (top) and after (bottom) images of their faint host galaxies. Hubble measured supernovae also hint that the Dark Energy's repulsive force is constant over cosmic time and so could be consistent with Einstein's original theory of gravitation. If the force actually changes with time, the Universe could still end in a Big Crunch or a Big Rip ... but not for an estimated 30 billion years.
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NASA Web Site Statements, Warnings, and Disclaimers
NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.
Based on Astronomy Picture
Of the Day
Publications with keywords: supernova - cosmology - dark energy
Publications with words: supernova - cosmology - dark energy
See also:
- APOD: 2023 October 11 Á NGC 1097: Spiral Galaxy with Supernova
- APOD: 2023 July 9 Á Doomed Star Eta Carinae
- APOD: 2023 May 22 Á Supernova Discovered in Nearby Spiral Galaxy M101
- Supernova Cannon Expels Pulsar J0002
- SN Requiem: A Supernova Seen Three Times So Far
- NGC 7814: Little Sombrero with Supernova
- Supernova in NGC 2525