Changes

# Brown dwarf [[star]]s and similarly massive but relatively non-luminous objects. Astronomers have in fact invented a new name for a class of objects that include brown dwarf stars and other massive objects: Massive Compact Halo Objects, or MACHOs.<ref name=Silk/><ref name=Miller/><ref name=WMAP2/><ref name=White>White, Martin. "[http://astro.berkeley.edu/~mwhite/darkmatter/dm.html Dark Matter]." Department of Astronomy, University of California at Berkeley, Berkeley, California, ca. 1995. Accessed July 28, 2008.</ref>

# Brown dwarf [[star]]s and similarly massive but relatively non-luminous objects. Astronomers have in fact invented a new name for a class of objects that include brown dwarf stars and other massive objects: Massive Compact Halo Objects, or MACHOs.<ref name=Silk/><ref name=Miller/><ref name=WMAP2/><ref name=White>White, Martin. "[http://astro.berkeley.edu/~mwhite/darkmatter/dm.html Dark Matter]." Department of Astronomy, University of California at Berkeley, Berkeley, California, ca. 1995. Accessed July 28, 2008.</ref>

# Supermassive [[black hole]]s. Astronomers are now attempting to detect these objects by their relativistic effects on light, in which they act as lenses.<ref name=WMAP2/>

# Supermassive [[black hole]]s. Astronomers are now attempting to detect these objects by their relativistic effects on light, in which they act as lenses.<ref name=WMAP2/>

# New, previously unknown forms of matter. Many cosmologists have formed hypotheses that suggest entirely new particles of matter. They call these Weakly Interactive Massive Particle, or WIMPs.<ref name=WMAP2/><ref name=Silk/><ref name=Miller/> Other cosmologists have suggested other types of particles, named ''axions''.<ref name=Hartnett/><ref name=axionnote>The name ''Axion'' is a registered trademark of the Colgate-Palmolive Company ([[USA]]) and was the name of a once-popular brand of laundry detergent used to pre-soak heavily-soiled garments before washing them with a conventional detergent. The astrophysicists who coined this name suggested that axions performed some kind of cosmic cleansing.</ref> The recently sought Higgs boson is another proposed dark-matter elementary particle.

# New, previously unknown forms of matter. Many cosmologists have formed hypotheses that suggest entirely new particles of matter. They call these Weakly Interacting Massive Particles, or WIMPs.<ref name=WMAP2/><ref name=Silk/><ref name=Miller/> Other cosmologists have suggested other types of particles, named ''axions''.<ref name=Hartnett/><ref name=axionnote>The name ''Axion'' is a registered trademark of the Colgate-Palmolive Company ([[USA]]) and was the name of a once-popular brand of laundry detergent used to pre-soak heavily-soiled garments before washing them with a conventional detergent. The astrophysicists who coined this name suggested that axions performed some kind of cosmic cleansing.</ref> The recently sought Higgs boson is another proposed dark-matter elementary particle.

# A new theory of gravity. In 1983, Mordecai Milgrom first suggested that Newtonian dynamics was insufficient to explain the gravitational interactions of massive objects like galaxies and galactic clusters. He therefore suggested a Modified Newtonian Dynamic, or MOND, in which gravitational attraction varied inversely to the first power of the orbital radius, not its square as Newton originally assumed.<ref name=Hartnett/><ref name=Thompson/>

# A new theory of gravity. In 1983, Mordecai Milgrom first suggested that Newtonian dynamics was insufficient to explain the gravitational interactions of massive objects like galaxies and galactic clusters. He therefore suggested a Modified Newtonian Dynamic, or MOND, in which gravitational attraction varied inversely to the first power of the orbital radius, not its square as Newton originally assumed.<ref name=Hartnett/><ref name=Thompson/>

# Neutrinos, which are detected and fall under the category of "warm dark matter" based on their momentum.  However, they only account for a small fraction of the dark matter required to explain the structure of galaxies.

# Neutrinos, which are detected and fall under the category of "warm dark matter" based on their momentum.  However, they only account for a small fraction of the dark matter required to explain the structure of galaxies.