earth science

• earth science

  the study of the earth and its neighboring planet
• geology, meteorology, oceanography, and astronomy

  are the four basic areas of earth science
• Edwin Hubble

  in the late 1920's, this american astronomer made a very interesting and important discovery, the expanding universe
• the universe is expanding, just as predicted by einstein's theory of general relativity.
• the diameter of the universe is infinite but should be at least 91 billion light years (1 light year is equal to 9.4607 x 10^12 km) its density is 4.5 x 10^-31 g/cm^3
• hydrogen, helium, and lithium are the most abudant elements
• the building blocks of galaxy is stars that are born out of clouds of gas and dust in galaxies. instabilities within the clouds eventually result in gravitational collapse, rotation, heating, and transformation into a protostar
• protostar: a contracting mass of gas which represents an early stage in the formation of a star, before nucleosynthesis begun

  
  

  the hot core of a future star as thermonuclear reactions set in
• nucleosynthesis: the process whereby heavier chemical elements are formed from lighter ones through nuclear fusion reactions inside stars or during supernovae explosions.
• stellar evolution: the changes that occur in a star throughout its lifetime, including its birth, growth, maturity, death, and eventual demise.
• red giant: a dying star with a swollen outer layer that glows red due to low surface temperature.
• a galaxy is cluster of billions of stars and clusters of galaxies form superclusters
• galaxy: a system consisting of many millions or even billions of stars bound together by gravity; our own Milky Way Galaxy contains about 100 billion stars
• supercluster: a group of several hundred or more galaxy clusters held together by mutual attraction
• supercluster: a group of galaxies held together by gravitational attraction
• the universe comprises all space and time and all matter and energy in it.
• the universe is made of 4.6% baryonic matter (ordinary matter consisting neutrons, electrons, and protons: atoms, planets, stars, galaxies, nebulae, and other bodies)
• dark energy makes up 72% of the universe's total mass-energy content - its nature remains unknown
• cosmology is the scientific study of the origin, evolution, and eventual fate of the entire universe
• the universe is made of 24% of cold dark matter (matter that has gravity but does not emit light)
• the big bang theory states that the universe began as an infinitely dense point called singularity
• the universe is made of 71.4% dark energy (a source of anti gravity)
• the universe is made of 0.5% ordinary matter (protons, neutrons, and electrons)
• dark matter is composed of particles that do not absorb, reflect, or emit light, so they cannot be detected by observin electromagnetic radiation
• 3.8 billion years ago, life took root on earth
• life started with single celled organisms
• the sollar system comprises the sun, eight planets, dwarf planets, satellites, asteroids, comets, other minor bodies such as those in the kuipers belt and interplanetary dust
• the solar system formed from a cloud of gas and dust called the solar nebula about 4.6 billion years ago
• the eight planets are mercury, venus, earth, mars, jupiter, saturn, uranus, and neptune
• the asteroid belt lies between mars and jupiter
• meteoroids are smaller asteroids
• the kuiper belt lies beyond neptune (30 to 50 AU, 1 AU = Sun-Earth distance = 150 million km) and comprises numerous rocky or icy bodies a few meters to hundreds of kilometers in size.
• the Oort cloud is a spherical region of icy bodies that orbit the sun beyond Neptune
• the Oort cloud marks the outer boundary of the solar system and is composed of icy objects
• the age of the solar system is at 4.6 billion years old based on the radioactive dating meteorites
• our solar system is located in the milky way galaxy which is about 100 million light years across (1 light year is equal to 9.4607 x 10^12 km)
• the solar system revolves around the galactic center once in about 240 million years
• Planetesimals are small, irregularly shaped bodies formed by colliding matter.
• A nebula is a cloud of gas and/or dust in space.
• According to the nebular theory, the sun and planets formed from a rotating disk of dust and gases.