Cosma Home > Communication > Knowledge > Realm > Physical > Universe > Planetary System > Star




Physical Realm
Universe Astronomical Instrument
Galaxy Milky Way, Andromeda
Planetary System Star, Brown Dwarf, Planet, Moon

Solar System Sun
Terrestrial Planet Mercury, Venus, Earth (Moon), Mars
Asteroid Belt Ceres, Vesta
Jovian Planet Jupiter, Saturn, Uranus, Neptune
Trans-Neptunian Object
Kuiper Belt Pluto, Haumea, Makemake
Scattered Disc Eris, Sedna, Planet X
Oort Cloud Etc. Scholz’s Star
Small Body Comet, Centaur, Asteroid


  • Touch the Sun (12/6/2019) - Remember how Icarus wanted to touch the Sun, but met his demise instead? Well, scientists at NASA wanted to touch the Sun too, but unlike Icarus, they succeeded! Better yet, they are beginning to share what they learned by doing it! Before we get into all of that, let’s go back and start at the … Continue reading Touch the Sun
  • Halloween@NASA (10/31/2019) - The folks at NASA love Halloween, and they do something to celebrate every year. For example, the engineers at NASA Jet Propulsion Lab have been holding a pumpkin carving contest for almost a decade, and stories about their ingenuity invariably make it into the news. Here’s a video from Wired about their 2016 competition. Here’s … Continue reading Halloween@NASA
  • Get Lost in Space! (9/14/2018) - Way back in August, in anticipation of the start of a new school year, I set out to update the pages on this site related to space. Those pages tend to be popular among the teachers and students who use Cosma, and I happen to enjoy updating them, too. It sounded like a short, fun … Continue reading Get Lost in Space!
  • Milky Way Lost & Found (8/15/2018) - Have you seen the Milky Way? You may think that you have, but are you sure? Unless you live in an extremely remote area, or you’ve visited one, then you probably haven’t seen our own galaxy, the Milky Way, very well, or at all. Worse yet, you may not even realize that it’s missing. The … Continue reading Milky Way Lost & Found
  • Umbraphiles (8/20/2017) - umbraphile : One who loves eclipses, often travelling to see them. — Wiktionary Yes, this is that obligatory post about “The Solar Eclipse” (NASA, Wikipedia). Of course, there had to be one — eclipses really are just too cool to ignore. You’ve already been bombarded with explanations of the science and history of eclipses, but … Continue reading Umbraphiles
  • TRAPPIST-1 (2/23/2017) - You’ve probably heard that NASA has found a trove of “Earth-like” planets circling the TRAPPIST-1 system roughly 40 light years away, but just in case you haven’t, here’s a short 2 minute AP video about the discovery. Here’s another video from NASA/JPL with more explanation. Most entertainingly, here’s a 360° YouTube Video published by NASA/JPL … Continue reading TRAPPIST-1


These are organized by a classification scheme developed exclusively for Cosma. More…



Stars Reference (National Geographic)
Star Portal (Wikipedia)


star : a self-luminous gaseous spheroidal celestial body of great mass which produces energy by means of nuclear fusion reactions — Webster

OneLook, Free Dictionary, Wiktionary, Urban Dictionary


Roget’s II (, Merriam-Webster Thesaurus, Visuwords


Star is a luminous sphere of plasma held together by its own gravity. The nearest star to Earth is the Sun. Many other stars are visible to the naked eye from Earth during the night, appearing as a multitude of fixed luminous points in the sky due to their immense distance from Earth. Historically, the most prominent stars were grouped into constellations and asterisms, the brightest of which gained proper names. Astronomers have assembled star catalogues that identify the known stars and provide standardized stellar designations. However, most of the stars in the Universe, including all stars outside our galaxy, the Milky Way, are invisible to the naked eye from Earth. Indeed, most are invisible from Earth even through the most powerful telescopes.

For at least a portion of its life, a star shines due to thermonuclear fusion of hydrogen into helium in its core, releasing energy that traverses the star’s interior and then radiates into outer space. Almost all naturally occurring elements heavier than helium are created by stellar nucleosynthesis during the star’s lifetime, and for some stars by supernova nucleosynthesis when it explodes. Near the end of its life, a star can also contain degenerate matter. Astronomers can determine the mass, age, metallicity (chemical composition), and many other properties of a star by observing its motion through space, its luminosity, and spectrum respectively. The total mass of a star is the main factor that determines its evolution and eventual fate. Other characteristics of a star, including diameter and temperature, change over its life, while the star’s environment affects its rotation and movement. A plot of the temperature of many stars against their luminosities produces a plot known as a Hertzsprung–Russell diagram (H–R diagram). Plotting a particular star on that diagram allows the age and evolutionary state of that star to be determined.

A star’s life begins with the gravitational collapse of a gaseous nebula of material composed primarily of hydrogen, along with helium and trace amounts of heavier elements. When the stellar core is sufficiently dense, hydrogen becomes steadily converted into helium through nuclear fusion, releasing energy in the process. The remainder of the star’s interior carries energy away from the core through a combination of radiative and convective heat transfer processes. The star’s internal pressure prevents it from collapsing further under its own gravity. A star with mass greater than 0.4 times the Sun’s will expand to become a red giant when the hydrogen fuel in its core is exhausted. In some cases, it will fuse heavier elements at the core or in shells around the core. As the star expands it throws a part of its mass, enriched with those heavier elements, into the interstellar environment, to be recycled later as new stars. Meanwhile, the core becomes a stellar remnant: a white dwarf, a neutron star, or if it is sufficiently massive a black hole.

Binary and multi-star systems consist of two or more stars that are gravitationally bound and generally move around each other in stable orbits. When two such stars have a relatively close orbit, their gravitational interaction can have a significant impact on their evolution. Stars can form part of a much larger gravitationally bound structure, such as a star cluster or a galaxy. — Wikipedia

Stars (Eric Weisstein’s World of Astronomy, Wolfram Research)
David Darling’s Internet Encyclopedia of Science
Encyclopædia Britannica


Guide to Stars & Galaxies (


Stars (Wolfram Alpha)


Stellar Astronomy is the study of stars and stellar evolution, and it is fundamental to our understanding of the Universe. The astrophysics of stars has been determined through observation and theoretical understanding; and from computer simulations of the interior. Star formation occurs in dense regions of dust and gas, known as giant molecular clouds. When destabilized, cloud fragments can collapse under the influence of gravity, to form a protostar. A sufficiently dense, and hot, core region will trigger nuclear fusion, thus creating a main-sequence star. — Wikipedia



History of Stars (Universe Today)


Quotations Page


WorldCat, Library of Congress, UPenn Online Books, Open Library



Stars & Star Clusters (Ask an Astronomer, Cornell University)
Stars (Cosmos4Kids)


Crash Course Astronomy (YouTube)

OER Commons: Open Educational Resources



Science Daily,, NPR Archives








OEDILF: The Omnificent English Dictionary In Limerick Form


Song Lyrics



Stars News -- ScienceDaily News about Stars. Read science articles and see images on the birth of monstrous stars, brown dwarfs and red giants. Consider stellar evolution and more.

  • Astronomers dissect the anatomy of planetary...
    on January 20, 2021 at 12:43 am

    Images of two iconic planetary nebulae taken by the Hubble Space Telescope are revealing new information about how they develop their dramatic features.

  • A 'super-puff' planet like no other
    on January 18, 2021 at 4:31 pm

    Astronomers discover that the core mass of exoplanet WASP-107b is much lower than previously thought possible for a gas-giant planet.

  • X-Rays surrounding 'Magnificent 7' may be traces...
    on January 15, 2021 at 4:03 pm

    Theoretical physicists suggest that never-before-observed particles called axions may be the source of unexplained, high-energy X-ray emissions surrounding a group of neutron stars.

  • Researchers rewind the clock to calculate age and...
    on January 15, 2021 at 4:03 pm

    Astronomers are winding back the clock on the expanding remains of a nearby, exploded star. By using NASA's Hubble Space Telescope, they retraced the speedy shrapnel from the blast to calculate a more accurate estimate of the location and time of the stellar detonation.

  • Astronomers document the rise and fall of a...
    on January 14, 2021 at 11:06 pm

    Astronomers have catalogued 126 years of changes to HS Hydra, a rare evolving eclipsing binary star system. Analyzing observations from astro-photographic plates in the late 1800s to TESS observations in 2019, they show that the two stars in HS Hydra began to eclipse each other around a century ago, peaking in the 1960s. The degree of eclipsing then plummeted over the course of just a half century, and will cease around February 2021. - latest science and technology news stories internet news portal provides the latest news on science including: Physics, Nanotechnology, Life Sciences, Space Science, Earth Science, Environment, Health and Medicine.

  • Students discover bright lensed galaxy in the...
    on January 14, 2021 at 1:38 pm

    The night sky is a natural time machine, used by cosmologists to explore the origins and evolution of the universe. Reaching into the depths of the past, a class of undergraduate students at the University of Chicago sought to do the same—and uncovered an extraordinarily distant galaxy in the early cosmos.

  • Study investigates emission from a distant red...
    on January 13, 2021 at 2:00 pm

    Using the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, an international team of astronomers has performed observations of HSC J120505.09−000027.9—the most distant red quasar so far detected and found that it showcases an extended emission of ionized carbon. The finding is reported in a paper published January 4 on

  • A planet called KOI-5Ab orbits in a triple-star...
    on January 12, 2021 at 2:26 pm

    Shortly after NASA's Kepler mission began operations back in 2009, it identified what was thought to be a planet about the size of Neptune. Called KOI-5Ab, the planet, which was the second new planet candidate to be found by the mission, was ultimately forgotten as Kepler racked up more and more planet discoveries. By the end of its mission in 2018, Kepler had discovered a whopping 2,394 exoplanets, or planets orbiting stars beyond our sun, and an additional 2,366 exoplanet candidates, […]

  • Unveiling the double origin of cosmic dust in the...
    on January 11, 2021 at 5:27 pm

    Two billion years after the Big Bang, the Universe was still very young. However, thousands of huge galaxies, rich in stars and dust, were already formed. An international study, led by SISSA—Scuola Internazionale Superiore di Studi Avanzati, now explains how this was possible. Scientists combined observational and theoretical methods to identify the physical processes behind their evolution and, for the first time, found evidence for a rapid growth of dust due to a high concentration of […]

  • Image: Hubble views a dazzling 'fireworks galaxy'
    on January 11, 2021 at 12:31 pm

    The galaxy NGC 6946 is nothing short of spectacular. In the last century alone, NGC 6946 has experienced 10 observed supernovae, earning its nickname as the Fireworks Galaxy. In comparison, our Milky Way averages just one to two supernova events per century. This NASA/ESA Hubble Space Telescope image shows the stars, spiral arms, and various stellar environments of NGC 6946 in phenomenal detail.