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Explanation: A quasar slightly depleted of a specific color of light may indicate that our universe is filled with massive amounts of ionized hydrogen. Light from QSO H1821+643, pictured above, comes to us from about a quarter of the way across the visible universe. Detailed analysis now indicates that a tiny amount of this quasar's light was absorbed by intervening ionized oxygen. Astronomers intuit that this oxygen is surely accompanied by much more abundant ionized hydrogen, which would otherwise be invisible. The oxygen is thus thought to be the tip of a tremendous iceberg, indicating a universe filled with proton and electron clouds so vast they likely exceed the mass of all the stars combined. Still, this is only a small part of the long-sought dark matter astronomers have been searching for. Our universe is thought to be filled with much more abundant, much stranger forms of dark matter.
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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: universe - hydrogen - ionized hydrogen - dark matter - quasar
Publications with words: universe - hydrogen - ionized hydrogen - dark matter - quasar
See also:
- APOD: 2024 December 1 Á Cosmic Latte: The Average Color of the Universe
- APOD: 2024 October 20 Á Dark Matter in a Simulated Universe
- APOD: 2024 July 1 Á Time Spiral
- APOD: 2024 January 1 Á NGC 1232: A Grand Design Spiral Galaxy
- APOD: 2023 December 31 Á Illustris: A Simulation of the Universe
- APOD: 2023 July 5 Á A Map of the Observable Universe
- APOD: 2023 June 29 Á A Message from the Gravitational Universe