1. Space Exploration
1.1. the benefits of space exploration
1.1.1. spinoff
1.1.1.1. a secondary beneficial effect or product of a thing or and activity
1.1.2. artificial satellite
1.1.2.1. a device placed in orbit around Earth or another celestial object to observe it and gather data about it
1.1.3. geostationary orbit
1.1.3.1. an orbit in which a satellite orbits at the same rate as the object rotates, causing the satellite to remain over the same spot on the celestial object
1.1.4. G.P.S.
1.1.4.1. global positioning system, works through the many satellites orbiting Earth that transmit low-energy microwave signals
1.1.4.2. three closest satellites are used to determine the position of a GPS reciever
1.2. the challenges of space exploration
1.2.1. microgravity
1.2.1.1. the condition in which the gravitational forces that act on a mass are greatly reduced, giving a feeling of weightlessness
1.2.2. challenges of physical environment
1.2.2.1. no air or water
1.2.2.2. solar radiation
1.2.2.3. space debris
1.2.2.4. temperature (extremely hot or extremely cold)
1.2.2.5. no atmosphere
1.2.2.6. living in confinement for a very long time
2. Our Universe
2.1. the universe and the objects in it
2.1.1. astronomy
2.1.1.1. the study of the universe and the objects in it
2.1.2. celestial objects
2.1.2.1. the objects that we can see in the sky
2.1.2.2. examples: sun, moon, earth, other planets and stars
2.1.3. solar system
2.1.3.1. the Sun together with all the planets and the other celestial objects that are held by the Sun's gravitational attraction and orbit around it
2.1.4. nuclear fusion
2.1.4.1. the process in which the nuclei of atoms fuse together and form larger atoms
2.1.5. star
2.1.5.1. a hot ball of plasma, an electrically charged gas, that shines because nuclear fusion is taking place at its core
2.1.6. astronomical unit (AU)
2.1.6.1. a unit of measurement in space which equates to the average distance between the sun and the earth which is about 150 million km
2.1.7. light-year (ly)
2.1.7.1. a unit of measurement in space that equates to the distance that a beam of light can travel through space in one year which is about 63 000 AU or 9000 billion km
2.1.8. supernova
2.1.8.1. the term used for when a star explodes at the end of its lifespan
2.1.8.2. only high mass stars supernova
2.1.9. nebula
2.1.9.1. a large cloud of dust and gas that is the result of debris from the explosion of a star
2.1.9.2. new stars often develop in the nebula from its gas and dust
2.1.10. dark matter
2.1.10.1. refers the the matter in the universe that is invisible because it does not interact with light or any other kind of radiation
2.1.10.2. it is believed that about 90% of the universe is composed of dark matter
2.1.11. black hole
2.1.11.1. a region of space where gravity is so strong that nothing, not even light, can escape
2.1.12. Milky Way
2.1.12.1. the galaxy that we live in
2.1.12.2. about 100 000 ly in diameter and contains about 200 billion stars
2.1.13. the Big Bang Theory
2.1.13.1. a theory that states that he universe formed approximately 13.7 billion years ago when an indefinitely dense point suddenly and rapidly expanded in a single moment
2.1.14. the shapes of galaxies
2.1.14.1. spiral/barred spiral
2.1.14.1.1. have spiral-shaped arms coming from the centre
2.1.14.1.2. barred spiral galaxies seem to have a bar across its diameter
2.1.14.1.3. tend to have younger stars due to the fact that there is more dust
2.1.14.2. elliptical
2.1.14.2.1. circular-like, comparable to a flattened sphere
2.1.14.2.2. can range from nearly spherical to football-shaped
2.1.14.3. irregular
2.1.14.3.1. their shape does not fit into a shape category
2.1.14.3.2. are likely irregularly shaped due to galaxies colliding and combining or galaxies getting close and drawing stars away with their gravitational force
2.2. stars
2.2.1. protostar
2.2.1.1. a star in its first stage of formation
2.2.2. general mass categories
2.2.2.1. low mass stars
2.2.2.1.1. these stars turn into white then black dwarfs at the end of their lifespans
2.2.2.2. medium mass stars
2.2.2.2.1. these stars turn into white then black dwarfs at the end of their lifespans
2.2.2.2.2. the Sun is a medium mass star
2.2.2.3. high mass stars
2.2.2.3.1. these stars turn into red giants then explode/supernova at the end of their lifespans
2.2.3. white dwarf
2.2.3.1. small white stars that used to be a low or medium mass stars and will turn into black dwarfs
2.2.4. red giant
2.2.4.1. huge red stars that used to be high mass stars and will explode/supernova
2.2.5. Hertzsprung-Russell diagram
2.2.5.1. a way to organize stars, sorted based off of colour, luminosity and surface temperature
2.3. the Sun
2.3.1. core
2.3.1.1. the centre of the Sun where nuclear fusion takes place
2.3.1.2. pressure is high and temperatures are at least 15 million degrees Celsius
2.3.2. radiative zone
2.3.2.1. plasma is very dense and light takes at least 100 000 to pass through it
2.3.3. convective zone
2.3.3.1. the hot plasma goes to the top of this zone, and cooler plasma sinks back closer to the core where it is reheated and the process repeats
2.3.4. photosphere
2.3.4.1. is usually considered to be the boundary between the inside and outside of the Sun
2.3.4.2. is where the Sun's yellow colour originates from
2.3.5. chromosphere
2.3.5.1. a thin layer above the photosphere
2.3.5.2. is red, but the photosphere is so bright that it cannot be seen unless there is a solar eclipse
2.3.6. corona
2.3.6.1. the outermost layer of the Sun
2.3.6.2. extends for millions of kilometers beyond the chromosphere
2.3.7. sunspots
2.3.7.1. a region on the Sun's surface that is cooler than the surrounding area and is slightly darker in comparison
2.3.7.2. these indicate where the magnetic pull of the Sun is stronger, since this slows convection
2.3.8. prominence
2.3.8.1. a large, often curved, bright stream of particles extending outward from the photosphere into the corona
2.3.8.2. these may last for many hours
2.3.9. solar flames
2.3.9.1. a massive explosion at the surface of the Sun
2.3.9.2. usually originates where the magnetic field breaks out of the Sun's surface and interacts with the chromosphere and corona
2.3.9.3. fling plasma into space
2.3.10. coronal mass ejection
2.3.10.1. an extremely powerful type of solar flare
2.3.10.2. when plasma from these types of solar flares reach Earth, the magnetic field of Earth protects us, but these can still damage satellites and electrical transmission lines
2.4. planets
2.4.1. four inner planets
2.4.1.1. made of rocky material
2.4.1.1.1. Mercury
2.4.1.1.2. Venus
2.4.1.1.3. Earth
2.4.1.1.4. Mars
2.4.2. four outer planets
2.4.2.1. made of gaseous material, mainly hydrogen and helium
2.4.2.1.1. Jupiter
2.4.2.1.2. Saturn
2.4.2.1.3. Uranus
2.4.2.1.4. Neptune
2.4.3. asteroid belt
2.4.3.1. a large band located between Mars and Jupiter composed of many rocks with extremely varying size
2.4.4. comet
2.4.4.1. celestial objects made of ice and dust that orbit the Sun and can sometimes be seen from Earth
2.4.5. metor
2.4.5.1. meteoroid that burns as it enters Earth's atmosphere
2.4.5.2. is called a meteorite when it strikes Earth's surface