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Universe Simulation. By Illustris Collaboration

The Universe

“The story so far:In the beginning the Universe was created. This has made a lot of people very angry and been widely regarded as a bad move.”
Douglas Adams, The Restaurant at the End of the Universe

The Universe is all of time and space and its contents. The Universe includes planets, natural satellites, minor planets, stars, galaxies, the contents of intergalactic space, the smallest subatomic particles, and all matter and energy. The observable universe is about 28 billion parsecs (91 billion light-years) in diameter at the present time.Read More

The Trifid Nebula (NGC 6514). By The Subaru Telescope (NAOJ), Hubble Space Telescope, Martin Pugh; Processing: Robert Gendler

Cosmic Dust

Cosmic dust is dust which exists in outer space. Most cosmic dust particles are between a few molecules to 0.1 µm in size. A smaller fraction of all dust in space consists of larger refractory minerals that condensed as matter left the stars. It is called “stardust” and is included in a separate section below. The dust density in the local interstellar medium of the Local Bubble is approximately 10-6 × dust grain/m3 with each grain having a mass of approximately 10-17 kg.Read More

Interstellar Clouds. By ESO/APEX/ATLASGAL consortium/NASA/GLIMPSE consortium/ESA/Planck

Interstellar Medium

In astronomy, the interstellar medium (ISM) is the matter that exists in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, as well as dust and cosmic rays. It fills interstellar space and blends smoothly into the surrounding intergalactic space.Read More

The Helix Nebula (NGC 7293). By NASA, WIYN, NOAO, ESA, Hubble Helix Nebula Team, M. Meixner (STScI), & T. A. Rector (NRAO)

Planetary Nebula

A planetary nebula is a kind of emission nebula consisting of an expanding, glowing shell of ionized gas ejected from old red giant stars late in their lives. They are a relatively short-lived phenomenon, lasting a few tens of thousands of years, compared to a typical stellar lifetime of several billion years.Read More