Cosmology: Formation of the Universe and Stars

• The universe is 13.7 billion years old.
• The solar system is 4.6-5 billion years old.
• The solar nebular hypothesis explains the solar system's formation: gas and dust around the sun clump and form planets.
• The five major steps in the scientific method include: form a question, hypothesis, gather data, test, make a theory.
• Science can only disprove theories; a theory is the best current explanation for observed phenomena.
• Only about 17% of the universe is visible with current instruments.
• Stars and galaxies account for only 5% of the 17% visible universe.
• In a supernova, ejected material gets shot out, and the star collapses into a neutron star or black hole.
• Stars in the Hertzsprung-Russell diagram are ranked bottom to top by increasing brightness and decreasing magnitude, right to left by increasing temperature, and spectral class.
• The early universe was composed of 75% hydrogen and 25% helium.
• There are approximately 2 trillion galaxies in the universe.
• The sun is 4.25 light years away from Proxima Centauri, the next nearest star in the Milky Way galaxy.
• The Milky Way galaxy will collide with the Andromeda galaxy in 4.5 billion years.
• Luminosity and temperature are two parameters used to plot a point on the H-R diagram.
• Gamma rays, visible light, microwaves, and radio waves belong to the electromagnetic spectrum.
• A teaspoon of matter from a neutron star would weigh millions of tons.
• Gravity on a neutron star is two times that of the sun it originates from.
• Black holes cannot be seen into because gravity is so strong that it pulls in light.
• A solar flare is a sudden and intense burst of radiation from the sun.
• The sun is 4.5 billion years old.
• The sun's surface is hotter compared to areas with sunspots.
• Solar wind is made up of charged particles and radiation.
• Planets in the solar system are grouped into Jovian and terrestrial categories.
• The asteroid belt is located between Mars and Jupiter.
• The four different kinds of meteorites include: stony, stony iron, iron/nickel, and carbonaceous chondrite.
• Pluto was declassified as a planet because it is too small, has an elliptical orbit, and is not the biggest thing in its orbit path.
• The heliosphere is 100 AU in all directions from the sun.
• The proper alignment for a solar eclipse is sun, moon, earth in that order.
• Catastrophism states that all of Earth's features were formed quickly by great catastrophes.
• Uniformitarianism states that the physical, chemical, and biological laws that operate today have also operated in the geological past.
• The four major principles of geology used for sequencing layered bedrock are: principle of superposition, original horizontality, cross-cutting relationships, and inclusions.
• Sequenced beds give relative dating but do not provide a specific date.
• In the periodic table, the letter Y stands for yttrium.
• A coprolite is fossilized poop.

Rocks, Minerals, Structures and Properties

• A rock is a solid mineral material that occurs naturally.
• A mineral is a solid inorganic substance with a definite crystalline structure.
• In a geologic time chart, the oldest layers are at the bottom, and the youngest are at the top.
• The Mohs hardness scale includes: Diamond (10), Corundum (9), Topaz (8), Quartz (7), Orthoclase (6), Apatite (5), Fluorite (4), Calcite (3), Gypsum (2), and Talc (1).
• Mineral properties used to identify minerals include: hardness, density, cleavage, crystallography, electrical conductivity, magnetism, radioactivity, and fluorescence.
• Types of bonding in minerals include: ionic, covalent, and metallic bonding.
• Lithification turns loose sediment into solid rock.
• Metamorphism transforms existing rocks into different rocks with different properties.
• Melting involves heat and pressure turning rock into magma.
• Crystallization involves cooling and solidification.
• Weathering, transportation, and deposition.
• The four spheres of geology for Earth are: atmosphere, biosphere, hydrosphere, and geosphere.