EARTH SCIENCE lesson 1

• baryonic matter- ordinary matter consisting of protons, neutrons and electrons that compaires atoms, planets, stars and galaxies
• dark matter - matter that has gravity, but does not emit light
• dark enerygy- a source of anti-gravity,a force that counteracts gravity and causes the universe to expand
• protostar- an early stage in the formation of a start resulting from the gravitational collapse of a cloud of gas
• thermonuclear reaction- a nuclear fusion reaction responsible for the energy produced by stars
• main sequence stars- that fuse hydrogen atoms to form helium atoms in thier cores, outward pressure resulting from nuclear fusion is balanced by gravitational forces
• light years- the distance light can travel in year
• any explanation of the origin of the universe should be consistant about its - compisition
• It is made of 4.6% baryonic matter (“ordinary” matter consisting of protons, electrons, and neutrons: atoms, planets, stars, galaxies, nebulae, and other bodies), 24% cold dark matter (matter that has gravity but does not emit light), and 71.4% dark energy (a source of anti-gravity)
• Hydrogen, helium, and lithium are the three most abundant elements.
• Stars - the building block of galaxies-are born out of clouds of gas and dust in galaxies. Instabilities within the clouds eventually results into gravitational collapse, rotation, heating up, and transformation into a protostar-the hot core of a future star as thermonuclear reactions set in.
• Stars like our Sun burnup hydrogen in about 10 billion years.
• A galaxy is a cluster of billions of stars and clusters of galaxies form superclusters
• Based on recent data, the universe is 13.8 billion years old. The diameter of the universe is possibly infinite but should be at least 91 billion light-years
• In 1929, Edwin Hubble announced his significant discovery of the “redshift” and its interpretation that galaxies are moving away from each other, hence as evidence for an expanding universe, just as predicted by Einstein’s Theory of General Relativity.
• big bang- is how astronomes explain the way universe began
• 13.8 billion years ago- with massive expansion
• according to many scientist it came on massive expansion
• georges lemaitre- the universe startes as just a single point
• georges lemaitre- he said that the universe keeps on streching and expanding
• From time zero (13.8 billion years ago) until 10-43 second later, all matter and energy in the universe existed as a hot, dense, tiny state. It then underwent extremely rapid, exponential inflation until 10-32 second later after which and until 10 seconds from time zero, conditions allowed the existence of only quarks, hadrons, and leptons
• Then, Big Bang nucleosynthesis took place and produced protons, neutrons, atomic nuclei, and then hydrogen, helium, and lithium until 20 minutes after time zero when sufficient cooling did not allow further nucleosynthesis.
• From then on until 380,000 years, the cooling universe entered a matter-dominated period when photons decoupled from matter and light could travel freelyas still observed today in the form of cosmic microwave background radiation
• From 9.8 billion years until the present, the universe became dark-energy dominated and underwent accelerating expansion. At about 9.8 billion years after the big bang, the solar system was formed