Astronomy Notes PDF

Astronomy Astronomy is the scientific study of the universe, including celestial objects (stars, planets, comets, galaxies) and phenomena outside Earth’s atmosphere Astronomy helps us understand the Origin, structure, and future of the universe as well as Earths Place within it. Chapter 7 7.1 we...

Astronomy Astronomy is the scientific study of the universe, including celestial objects (stars, planets, comets, galaxies) and phenomena outside Earth’s atmosphere Astronomy helps us understand the Origin, structure, and future of the universe as well as Earths Place within it. Chapter 7 7.1 we use astronomical units and light years but what are they? Astronomical unit is the average distance from Earth to the Sun. Ex. Earth is 1 AU from the Sun. Light is the distance of light that travels in a year. Ex. Alpha Centauri. The closest star system is 4.3 light years away. -​ Spiral Galaxies: Disk shape, stars form in arms, both young and old stars. -​ Elliptical Galaxies: Round/oval shape, no star formation, mostly old stars. Most common type! -​ Irregular Galaxies: No defined shape, often formed from collisions, active star formation. 7.3 Red shift is the light from distant galaxies shifts towards red wavelengths indicating the galaxies are moving away. This tells us the universe is expanding. ( Discovered by Edwin Hubble) Big Bang Theory (not necessarly important) States the universe began 13.7 billion years ago. It started from extremely dense and hot point which rapidly expanded. There are 2 evidences that supports the Big Bang Theory: Red shift andd Cosmic Microwave Background Radiation (CMB). Discovered in 1965 by Arno Benzias and Robert Wilson. The big bang theory made the first light elements: HYdrogen, helium and a litttle lithium. This happened in the first few minutes afte the Universe started when it was still super hot. Hubble’s law: -​ States that the speed at which a galaxy moves away is proportional to its distance from us -​ Implication: the farther a galaxy is the farther its receding. Supporting the idea of an expanding universe Balloon model of expansion: -​ Space expands like the surface of a balloon being inflated -​ Galaxies are like dots on the balloons surface. Moving father apart as the balloon expands. Current observations: -​ th e expansion of the universe is not slowing down; it is accelerating due to a mysterious force called dark energy. Chapter 8 8.1 What determines a star’s fate? It’s mass determines if it becomes a white dwarf, neutron star, or black hole. LIfe cycle of stars: determined by mass Low mass stars: Main sequence -> Red dwarf -> white dwarf (Proxima Centbrio) Medium mass stars: main sequence -> red giants -> planetary nebula -> white dwarf (Sun) High mas stars: main sequence -> supergiant -> supernova -> neutron star or black hole (Betelguese) 8.2 What’re major components of our solar system? -​ The Sun  -​ Planets; terrestrial planets (rocky planets: mercury, Venus, Earth, Mars Gas Giants (Gassy): Jupiter, Saturn, Uranus, Neptune Terrestrial planets Mercury: closest to sun, exteremly hot durring the day but freezing at night, no atmosphere, no moon Venus: Smaller in size to Earth but has thick toxic clouds, hottest planet because of thick atmosphere trapping heat (greenhouse effect). Rotates very slowly and backwards(retergograde rotation) Earth: The only planet known to support life, has liquid water on its surface and one moon, protected by a atmosphere that traps heat and shields from harmful radiation Mars: Known as the “red planet” due to its iron rich soil, has the largest volcano in the solar system(olympus moris), thin atmosphere; cold Gas giants Jupiter: largest planet in the solar system, known rom the great red spot(a giant storm), has at least 80 moons, including Titan which has an atmosphere. Uranus: Roates on its side )its axis tilted almost 90 degrees), pale blue colour due to methane in its atmosphere, very cold with faint rings and 27 known moons. Neptune: farthest from the sun, deep blue color and has the strongest winds in the solar system, has faint rings and 14 known moons, including Triton, which orbits backwards -​ Asteroid belt: Between mars and jupiter -​ Comets: ice and dust, glow when near the sun -​ Moon: Natural satellites like Earth’s moon 8.3 What effect do the Sun and Moon have on Earth? -​ Sun: provide light, heat and energy: causes seasons -​ Moon: Creates ides and stablizes Earth’s tilt. -​ Eclipses: Solar eclipse: Moon blocks the Sun Lunar eclipse: Earth block sunlight from reaching the Moon Chapter 9: 9.1 What was the Geocentric Theory? -​ He claimed earth was the center of the universe (eg. Ptolemy) -​ Replaced by the Hetriocentric Theory (SUn centered model) Thanks to Copernicus and Galileo -​ Hence Geocentric theory is when the Earth is the center of the Universe (Disproven by Galileo) 9.2 Whatre some benefits of space research and exploration? 1.​ Technology advancements: GPS, Satellites, Medical imaging. 2.​ Knowledge about planets, stars, and the Universe 3.​ Economic growth: New industries and jobs 9.3 what’re some costs and hazards? -​ Costs: Space exploration is very expensive -​ Hazards: -​ 1. Radiation exposure -​ Microgravity (weakens bones and muscles) -​ Accidents(Rocket failures) Supernova vs. Nebula ​ Supernova: ○​ A massive star explosion at the end of its life cycle. ○​ Example: Supernova SN 1987A. ​ Nebula: ○​ A cloud of gas and dust where new stars are born. ○​ Example: The Orion Nebula. Constellation vs. Star Cluster ​ Constellation: ○​ A pattern of stars in the sky. ○​ Example: Orion.  ​ Star Cluster: ○​ A group of stars that are physically close and formed together. ○​ Example: The Pleiades. Neutron Star vs. Black Hole ​ Neutron Star: ○​ The dense remnant of a massive star after it has exploded as a supernova. ○​ Example: The Crab Pulsar. ​ Black Hole: ○​ A region where gravity is so strong that nothing, not even light, can escape. ○​ Example: Sagittarius A* (black hole at the center of the Milky Way). Solar Flares vs. Solar Prominences vs. Sunspots ​ Solar Flares: ○​ Explosive bursts of energy and radiation from the Sun. ○​ Example: A flare observed in 2017. ​ Solar Prominences: ○​ Large loops of gas extending from the Sun’s surface. ○​ Example: The Solar Prominence of 2011. ​ Sunspots: ○​ Cooler, darker regions on the Sun’s surface caused by magnetic activity. ○​ Example: The sunspot cycle. Terrestrial Planets vs. Gas Giants ​ Terrestrial Planets: ○​ Small, rocky planets closest to the Sun. ○​ Example: Earth, Mars. ​ Gas Giants: ○​ Large planets made mostly of gas, far from the Sun. ○​ Example: Jupiter, Saturn. Comet vs. Asteroid ​ Comet: ○​ A small icy body that has a glowing tail when near the Sun. ○​ Example: Halley’s Comet. ​ Asteroid: ○​ A small rocky object, often found in the asteroid belt. ○​ Example: Ceres (the largest asteroid). Meteor vs. Meteoroid vs. Meteorite ​ Meteor:  ○​ A streak of light caused by a meteoroid entering Earth’s atmosphere. ○​ Example: A “shooting star.” ​ Meteoroid: ○​ A small rock or particle in space before it enters Earth’s atmosphere. ​ Meteorite: ○​ A meteoroid that survives its passage through the atmosphere and lands on Earth. ○​ Example: The Hoba meteorite in Namibia. Rotation vs. Revolution ​ Rotation: ○​ The spinning of a planet on its axis. ○​ Example: Earth’s 24-hour day. ​ Revolution: ○​ The movement of a planet around the Sun. ○​ Example: Earth’s 365-day orbit around the Sun. Solar Eclipse vs. Lunar Eclipse ​ Solar Eclipse: ○​ When the Moon blocks the Sun’s light from reaching Earth. ○​ Example: Total Solar Eclipse in 2017. ​ Lunar Eclipse: ○​ When Earth blocks the Sun’s light from reaching the Moon. ○​ Example: The Lunar Eclipse of 2019. Solstice vs. Equinox ​ Solstice: ○​ The longest and shortest days of the year, marking the start of summer or winter. ○​ Example: Winter Solstice (December 21), Summer Solstice (June 21). ​ Equinox: ○​ The two times of the year when day and night are equal. ○​ Example: Spring Equinox (March 20), Fall Equinox (September 23). Refracting Telescope vs. Reflecting Telescope ​ Refracting Telescope: ○​ Uses lenses to gather and focus light. ○​ Example: The refracting telescope at the Royal Greenwich Observatory. ​ Reflecting Telescope: ○​ Uses mirrors to gather and focus light. ○​ Example: The Hubble Space Telescope.