AST01 - Introduction to Astronomy: Major Historical Events

1054: Chinese astronomers observed the supernova that formed into the Crab Nebula
1570: Tycho Brahe conducted a detailed survey of the night sky
1609: Johannes Kepler developed the Laws of Planetary Motion
1687: Isaac Newton developed the Universal Law of Gravitation
1781: William Herschel discovered Uranus
1801: Giuseppe Piazzi discovered Ceres
1846: Urbein Le Verrier discovered Neptune
1930: Clyde Tombaugh discovered Pluto
1957: Launch of Sputnik 1
1961: Yuri Gagarin became the first man in space
1965: Discovery of the Cosmic Microwave Background
1975: Venera 9 became the first probe to land on Venus
1976: Viking 1 became the first probe to land on Mars
1977: Voyager 1 and 2 launched
2015: New Horizons Pluto Flyby

1865: The Manila Observatory (Meteorologica De Manila) was established in Intramuros by Jesuit Scientists, founded by Fr. Federico Faura
1993: Former President Fidel V. Ramos signed Proclamation Decree No. 130, declaring the celebration of National Astronomy Week every third week of February
2000: The Philippines became an Associate Member of the International Astronomical Union (IAU)
2019: The Philippine Space Agency was established through R.A. 11363

Cosmology: focused on the largest structure of the universe, studying its origin and evolution since the Big Bang
Astrochemistry: focuses on the chemical abundance, reactions, and interactions inside stars, interstellar medium, solar system, galaxies, and the Universe
Astrobiology: covers the origin, evolution, and future of life in the universe, investigating the possible migration of the human race to other worlds
Ethnoastronomy/Archaeoastronomy/Historical Astronomy: describes the unique practices, beliefs, and traditions of a certain group of people in relation to astronomy
Astronomy Education: deals with the transmission of astronomical learning, concepts, and knowledge for formal education or community outreach
Planetology: comparative analysis of the chemical, physical, environmental, astrophysical, biological, and atmospheric inquiry of different planets in the solar system and exoplanets

Light Year: the distance traveled by light in one year
Astronomical Unit (AU): the average distance between the Earth and the Sun (149 million kilometers or 93 million miles)
Parsec: 3.26 light years

Laplace's Nebula Theory (1796): the solar system began from a huge cloud of gas that collapsed under gravity, with planets formed by the condensation of annular rings around the Sun
Schmidt-Lyttleton Accretion Theory (1944): the Sun passed through a huge cloud of gas, acquiring matter to form planets through line accretion
Proto-planet Theory (1960): the solar system started with a cloud of dust and gas in a state of hypersonic turbulence, resulting in aggregation of masses
Capture Theory (1964): an interaction between a condensed solar mass star and a protostar of lesser mass, resulting in the formation of bodies like planets
The Solar Nebula Theory (1973): the solar system began with a slowly rotating nebula, with planet formation starting from a disc of 0.01 to 0.1 solar masses
The Modern Laplacian Theory (1974): a cool gas cloud condensed, with the central body's angular momentum only 1 percent of the system, resulting in the formation of planets in concentric rings

Asteroid Belt: the gap between Mars and Jupiter where hundreds of thousands of known asteroids orbit the Sun
Dwarf Planets in the Asteroid Belt: Ceres
Kuiper Belt: a distant version of the Asteroid Belt that extends from the orbit of Neptune out to a distance of well beyond 50 AU from the Sun
Dwarf Planets in the Kuiper Belt: Pluto, Haumea, Makemake, Eris
Oort Cloud: surrounds the entire solar system with a shell of frozen bits of ice and rock that stretches out to about a quarter of the way to the nearest star

Hertzsprung-Russell Diagram: plots the temperature of stars against their luminosity or color against their absolute magnitude, indicating a star's internal structure and evolutionary stage
Main Sequence stars: 90% of stars spend their lives in this stage
Red Giant or Super Red Giant: high luminosity, lower surface temperature, and larger radius
Helium-burning stars
White Dwarf Stars: the shed-off core of the red giant stars
Nebulae: huge clouds of gas and dust that can give birth to new stars

Large-scale structure in the universe, consisting of hundreds to thousands of galaxies bound together by gravity
Rich galaxy clusters: over 1000 galaxies, mostly elliptical and more concentrated towards the center
Poor galaxy clusters: fewer than 1000 galaxies, spread throughout a region as large as a rich cluster