THE SUN, EARTH, AND MOON • Astronomy: study of the space and the universe. EARLY ASTRONOMY • Includes all celestial bodies and phenomena. • Greeks made huge contributions to what we know of astronomy today • Came to conclusions about the cosmos using philosophical arguments and observational data HIPPARCHUS • Pre-Ptolemy • 190-120 BC • Mathematician • Measured the distance between the Earth and the moon using basic trigonometry • Invented the Astrolabe ASTROLABE ARISTOTLE • 384-322 BC • Philosopher and polymath • Polymath: wide range of knowledge (think da Vinci) • Used the curved shadow of Earth on the moon during the eclipse to assume that the Earth was round. • His belief was abandoned in the Middle Ages ERASTOSTHENES 276-194 B.C. • Mathematician • First successful attempt to establish the size of Earth. • Calculated circumference of the Earth using the Post of Alexandria and the Well at Syene. • C A L C U L AT I N G E A RT H ’ S CIRCUMFERENCE GEOCENTRIC VS HELIOCENTRIC • Geocentric Model • • In the ancient Greeks’ geocentric model, the moon, sun, and the known planets— Mercury, Venus, Mars, and Jupiter—orbit Earth. • Heliocentric Model • In the heliocentric model, Earth and the other planets orbit the sun CLAUDIUS PTOLEMY • 100-170 AD • Mathematician, astronomer, philosopher, geographer, and astrologer. • Believed in the Geocentric model. • Was proven incorrect by Galileo. • So why do we still learn about him? • Think back to scientific inquiry. Incorrect answers are just as important as correct answers. Incorrect answer narrow what we perceive as truth. ARISTARCHUS • 312-230 B.C. • Mathematician and astronomer • First Greek to believe in a sun-centered universe (heliocentric) • Attempted to calculate the distance between the Earth, Sun, and moon. • Though evidence supported it for 1500 years the Geocentric model dominated Western thought. Ptolemy created a model of the universe that accounted for the movement of the planets. Retrograde motion is the apparent westward motion of the planets with respect to the stars. PTOLOMAIC SYSTEM RETROGRADE MOTION • 1473-1543 NICOLAUS COPERNICUS • Polish mathematician and astronomer. • Copernicus concluded that Earth is a planet. He proposed a model of the solar system with the sun at the center. TYCHO BRAHE • 1546-1601 • Danish nobleman, astronomer, and writer. • Lost his nose in a sword fight and wore a “prosthetic” made of copper. • Invented devices that measured the locations of celestial bodies. • More precise observations than anyone else previously. • This especially goes for the position of Mars. • 1571-1630 • German astronomer • Played a key part in the 17th century scientific revolution. • Created what we know as “law of planetary motion”. JOHANNES KEPLER KEPLER’S LAWS 1. Orbits of the planets are elliptical. 2. Planets revolve around the sun at varying speed. 3. There is a proportional relationship between a planet’s orbital period and its distance to the sun. • Ellipse- oval-shaped path • AU- the average distance between the earth and the sun (150 million km) PLANET REVOLUTION GALILEO GALILEI • 1564-1642 • Italian polymath • Known as the father of: • Observational astronomy • Modern physics • Scientific method • Most important contributions were his descriptions of the behavior of moving objects. • Developed his own telescope and discovered a plethora of important discoveries: 1. Four satellites (moons) orbiting Jupiter 2. Planets are circular disks and not just bright points 3. Venus has phases just like the moon 4. The moon’s surface is extremely bumpy 5. There are spots (dark regions) on the sun’s surface GALILEO (CONT.) SIR ISAAC NEWTON • No, an apple did not fall on his head. • 1643-1727 • English mathematician, physicist, astronomer, theologian, and author. • Recorded by William Stukely and archived by the Royal Society: • “Why must apples always descend perpendicularly to the ground?” UNIVERSAL GRAVITATION • Gravity: the force of attraction that exists between any two masses. • Force decreases with distance. • Greater the mass, greater the force. STONEHENGE MOTIONS OF EARTH • Rotation: turning, or spinning, of a body on its axis. • Mean solar day • The time interval from one noon to the next (approx. 24 hrs). • Sidereal day • The time it takes for Earth to complete 360 degrees (approx. 23hr, 56 min, 4 sec) • Revolution: motion of a celestial body along a path around some point in space. • Perihelion • The time in January when Erath is closest to the sun. • Aphelion • The time in July when Earth is farthest from the sun. ROTATION VS REVOLUTION MOTIONS OF EARTH • Axis and the Seasons • The plane of the ecliptic is an imaginary plane • Connects earth’s orbit with the celestial sphere • The tilt in the axis leads to the yearly cycle of seasons. MOTIONS OF THE EARTH • Precession- traces out a cone over a period of 26,000 years • The solar system moves in the direction of the star Vega • The sun revolves around the galaxy • Earth is slowly approaching Andromeda, our galaxy neighbor APOGEE AND PERIGEE THE POINT AT WHICH THE MOON THE POINT AT WHICH THE MOON IS FARTHEST FROM EARTH. IS CLOSEST TO EARTH. LEONARDO DA VINCI • 1452-1519 • Italian polymath • Made the determination that the phases of the moon came from the light from the sun reflecting on earth’s surface. • Published in the Codex Leicester in 1510. • One of the most famous polymaths in history. PHASES OF THE MOON • Progression of changes in the moon’s appearance (monthly cycle) • Result of light from the sun reflected om earth’s surface and the motion of the moon. LUNAR MOTIONS • Synodic month: 29. 5 days. • Based on the moon’s phases. • Sidereal month: 27.33 days. • True period of the moon’s revolution around the earth. • The different of the two days is due to the Earth-moon system orbiting the Sun. • The period of rotation of the moon is the same as Earth. This causes the same lunar hemisphere to always face Earth. LUNAR MOTIONS TYPES OF ECLIPSES • Solar eclipses • Occur when the moon moves in a line directly between the Earth and the sun • Casts a shadow on Earth TYPES OF ECLIPSES • Lunar Eclipses • Occurs when the moon passes. through the Earth’s shadow • During a new-moon or full-moon phase, the moon’s orbit must cross the plane of the ecliptic for an eclipse to take place THE LUNAR SURFACE • Craters • A depression at the summit of volcano or where a meteorite impacted • Most craters were produced by the impact of rapidly moving debris • Rays • any of a system of bright, elongated streaks, sometimes associated with a crater on the moon. • Highlands • Densely-pitted, light-colored areas THE LUNAR SURFACE • Maria • Ancient beds of basalt that were formed when impacts allowed magma to bleed through the surface • A rille is a long channel associated with maria that are similar to a valley or trench. • Regolith • thin, layer consisting of loosely compacted, fragmented material believed to have been formed by repeated meteorite impacts THE MOON’S SURFACE Mare Imbrium (Sea of Rains) Kepler Crater Copernicus Crater Mare Tranquillitatus (Sea of Tranquility) TOPOGROPHY LUNAR HISTORY • The most widely accepted model for the origin of the moon is that when the solar system was forming, a body the size of Mars impacted Earth. The resulting debris was ejected into space, began orbiting around Earth, and eventually united to form the moon. MOON LANDING • The race to space was a monumental period of events that forever changed our relationship with the cosmos. • One of those events was known as the Apollo 11 mission that made Neil Armstrong and Buzz Aldrin the first ever humans on the moon. KATHERINE JOHNSON • In 1969, Neil Armstrong became the first man to walk on the moon. However… • …he would not have gotten there had it not been for Katherine Johnson and her precise mathematical calculations of the orbital trajectory for the Apollo 11 mission. • Lead to the movie Hidden Figures, in which she was played by Taraji P. Henson. • 1918-2020 • Born in West Virginia • Graduated from West Virginia State College. KATHERINE JOHNSON MARY JACKSON • 1921-2005 • Hampton,VA • Hampton Institute in Mathematics and Physical Science • Engineer • Staunch advocate for the rights of women and minority groups in the STEM fields. • Extracted data from wind tunnel and flight tests. • Born in 1942 in Monroe, NC • The George Washington University • Aeronautical Engineer • Wrote the computer program for a sonic boom that led to sonic boom minimization studies for 25 years. CHRISTINE DARDEN DOROT H Y VAUG H AN • Key figure in the desegregation of STEM fields. • 1910-2008 • Kansas City, MO • Mathematician • Math teacher in Farmville, VA during WWII. • First African American supervisor hired by NASA, monitoring the “West Area Computing” unit.