JPL/ NASA Chronicles of Discovery: Innovations IN SPACE, ON EARTH

GPS

From: JPL/ NASA Timeline: Chronicles of Discovery

INNOVATIONS: IN SPACE AND ON EARTH

  • Radar used for the first time to observe another planet when signals are bounced off Venus; a follow-up test reveals surface features as the planet rotates.
  • Digital image processing developed for the Mariner and ranger missions leads to many applications in medicine, law enforcement, and other fields.
  • Error-correcting codes designed to avoid dropouts in radio communication with Mariner spacecraft eventually find their way in to cell phones and compact discs.
  • Technology designed to purify “clean rooms” in which spacecraft are built are adapted for hospital operating rooms and other work environments.
  • JPL collaborates with the Department of Energy to develop low-cost solar panels for home energy and other applications.
  • 3-D computer animation techniques developed to model the flight of spacecraft lay the groundwork for computer-animated cartoon movies of the 1990s.
  • JPL debuts an experimental car powered by a hybrid mix of gasoline and electricity – a precursor of commercial models two decades.
  • Infrared technology from the Viking mission to Mars is adapted to create devices that are inserted into the ear to read body temperature.
  • A JPL team works with doctors from the Los Angeles Cedars-Sinai Medical Center to develop a tool for cleaning out clogged arteries without surgery, JPL excimer laser technology is evaluated as an alternative to balloon technology.
  • A JPL instrument called a spectrometer helps archeologist identify minerals on an ancient Guatemalan funeral mask.
  • An imaging system is created for the National Archives to monitor and preserve the original copies of the Constitution, the Declaration of Independence, and the Bill of Rights.
  • Explorers discover the lost city of Ubar, an outpost on the spice route of the Arabian Peninsula, thanks in part to images from radar imagers flown on the space shuttle.
  • Shuttle astronaut John Glenn helps test JPL’s Electronic Nose, a device that measures trace vapors in close environments. Applications include environmental monitoring, quality control, food processing, and medical diagnosis.
  • An ultrasonic drill is developed that adapts easily to extreme temperatures and can core the hardest rocks. The drill has application in space missions and in medicine.
  • JPL establishes a Global Positioning System ground network that provides highly precise location information for use in agriculture, earthquake monitoring, and aviation.
  • JPL’s rugged urban robot, known as “Urbie,” is developed as a prototype for military reconnaissance and police, emergency, and rescue personnel.
  • JPL scientists create a transparent welding curtain technology that maximizes protection from blue and ultra-violet radiation. They follow this with a superior technology for protective sunglasses for various light environments.
  • A tiny image sensor on a chip developed by JPL researchers originally for space imaging application has now become widely available for consumer use, cell phone cameras, digital still and video camera, and personal computer cameras use the image chip, which is easier to manufacture and consumes less power than other images sensors.
  • EPOXI is a multiple-use spacecraft. Originally Deep Impact, EPOXI was renavigated to a different comet, Hartley 2. EPOXI also observed extrasolar planets and tested the “Interplanetary Internet” from deep space.
  • JPL robot technology was used by a U.S. firm to create two mobile robots that investigated damage at Japan’s devastated Fukushima nuclear power station.
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JPL/ NASA Chronicles of Discovery: Timeline (1990-2011)

Mars Rovers

From: JPL/ NASA Timeline: Chronicles of Discovery

August 10, 1990: Magellan enters orbit around Venus. Over the next four years, it maps 98 percent of the planet’s surface.

October 6, 1990: The U.S. – European Ulysses spacecraft launches a mission to study the Sun and its poles.

October 29, 1991: En route to Jupiter, Galileo makes the first flyby of an asteroid when it passes by Gaspra.

August 10, 1992: The U.S. – French ocean-monitoring satellite Topex/ Poseidon launches.

August 28, 1993: Galileo flies by a second asteroid, Ida, on its way to Jupiter.

December 2, 1993: Shuttle astronauts take a spacewalk to install JPL’s Wide-Field and Planetary Camera 2 in the Hubble Space telescope, compensating for a flaw in the telescope’s main mirror. The instrument allows Hubble to capture remarkable images of galaxies, nebula, planets, and many other celestial objects.

April 9, 1994: A decade after the first shuttle radar imaging mission, the third in the series launches. A JPL instrument is combined with a German-Italian radar system.

December 7, 1994: Galileo arrives at Jupiter, delivering a descent probe into the giant planet’s swirling atmosphere.

August 17, 1996: The NASA Scatterometer launches aboard Japan’s Advanced Earth Observing Satellite. The instrument studies near-surface ocean winds.

November 7, 1996: Mars Global Surveyor launches on a mission to orbit the red planet.

December 4, 1996: Mars Pathfinder launches, carrying a lander and instrumented rover.

February 12, 1997: JPL teams with a Japanese spacecraft launched under the Space Very Long Baseline Interferometry program to make radio observations of the distant Universe.

July 4, 1997: Mars Pathfinder lands, delivering the first mobile rover to another planet, By the final data transmission on September 27, the mission returns 2.3 billion bits of information, including more than 16,500 lander images and 550 rover images.

September 12, 1997: Mars Global Surveyor enters orbit.

October 15, 1997: Cassini launches to travel 6-1/2 years to Saturn, where the European-built Huygens probe will descend to the surface of the shrouded moon Titan.

February 17, 1998: Voyager 1 passes another spacecraft to become the most distant human-made object in space.

October 24, 1998: Deep Space 1 launches on a mission to flight-test advanced technologies, including an ion propulsion system.

February 7, 1999: Stardust launches on a mission to fly past a comet and return samples of comet and interstellar dust to Earth.

June 19, 1999: The Quick Scatterometer satellite launches into Earth orbit to study near-surface ocean winds around the globe.

December 18, 1999: Two JPL instruments, the Multi-angle Imaging SpectroRadiometer and the Advanced Spacebourne Thermal Emission and Reflection Radiometer, launch aboard NASA’s Terra satellite.

December 20, 1999: The Activity Cavity Irradiance Monitor Satellite launches to study the energy output of the Sun.

February 11, 2000: The Shuttle Radar Topography mission launches. The instrument uses a pair of large antennas to make a near-global map of Earth’s topography.

December 30, 2000: En route to Saturn, Cassini flies by Jupiter, making joint observations of the giant plant with the Galileo spacecraft.

April 7, 2001: Mars Odyssey launches; it enters orbit at the red planet on October 24.

August 8, 2001: Genesis launches on a mission to return samples of the solar wind to Earth.

December 7, 2001: The U.S. – French Jason 1 oceanography satellite launches.

March 17, 2002: Twin Earth-orbiting satellites are launched under the gravity Recovery and Climate Experiment mission.

May 4, 2002: JPL’s Atmospheric Infrared Sounder instrument launches aboard the Aqua satellite to study Earth’s climate and weather.

April 28, 2003: Galaxy Evolution Explorer launches to study the history of star formation.

June 10, 2003: Mars Exploration Rover “Spirit” launches to Mars.

August 25, 2003: Spitzer Space Telescope launches. It uses infrared technology to study asteroids, dust-shrouded stars, and distant galaxies.

January 3, 2004: Mars Exploration Rover “Spirit” lands at Gusev Crater on Mars.

January 24, 2004: Mars Exploration Rover “Opportunity” lands at Meridiani Planum on Mars.

March 2, 2004: JPL’s Microwave Instrument on the Rosetta Orbiter launches.

May, 2004: The Mars Exploration Rover begins the first of several extended missions.

June 30, 2004: Cassini-Huygens enters Saturn’s orbit.

July 15, 2004: JPL’s Microwave Limb Sounder and Tropospheric Emission Spectrometer launch aboard the Aura satellite to study ozone in Earth’s atmosphere.

January 12, 2005: Deep Impact launches to encounter comet Tempel 1.

January 14, 2005: The Huygens probe lands on Titan, Saturn’s mysterious smoggy moon.

July 3, 2005: Deep Impact’s impactor collides with comet Tempel 1.

August 12, 2005: Mars Reconnaissance Orbiter launches to seek out the history of water on the red planet.

July 3, 2007: Deep Impact becomes the EPOXI mission, retargeted to comet Hartley 2.

August 4, 2007: Phoenix, a Mars lander, launches to the red planet.

August 13, 2007: The Stardust spacecraft is reactivated to conduct a follow-up visit to comet Tempel 1.

September 13, 2007: Mars Exploration Rover “Opportunity” descends into Victoria Crater.

September 27, 2007: The Dawn mission to asteroid Vesta and the dwarf planet Ceres launches.

May 25, 2008: Phoenix lands near Mars’ North Pole to dig for water ice and analyze the soil.

June 20, 2008: The Ocean Surface Topography/ Jason 2 mission launches.

June 30, 2008: Cassini begins its first extended mission, called the Saturn Equinox mission.

October 22, 2008: The Moon Mineralogy Mapper launches aboard India’s Chandrayaan-1.

March 6, 2009: The Kepler mission launches on a search for Earth-like planets.

March 14, 2009: JPL technology launches on the European Space Agency’s Herschel/ Planck mission.

June 18, 2009: Diviner launches aboard Lunar Reconnaissance Orbiter to map temperatures at the lunar North Pole.

December 14, 2009: Wide-field Infrared Survey Explorer launches. It will scan the sky in infrared light, creating a vast catalog of celestial objects.

May 20, 2010: The Mars Exploration Rover project passes a historic longevity record: “Opportunity” rover surpasses the duration record set by the Viking 1 lander of 6 years and 116 days operating on the Martian surface.

September 27, 2010: Cassini begins its second extended mission, named the Cassini Solstice Mission.

November 1, 2010: The giant 70-meter (230-foot) antenna at the Goldstone Deep Space Communications goes back on line tracking deep space missions after a seven-month upgrade.

November 4, 2010: Deep Impact-EPOXI flies by comet Hartley 2.

December 25, 2010: Mars Odyssey becomes the longest-serving spacecraft at Mars – 3,340 days in orbit.

June 10, 2011: Aquarius launches to study Earth’s sea-surface salinity.

July 15, 2011: The Dawn Spacecraft enters orbit around asteroid Vesta.

August 5, 2011: Juno launches to Jupiter to explore the origin and evolution of the giant planet.

September 10, 2011: Gravity Recovery and Interior Laboratory twin spacecraft launch to explore the Moon’s gravity.

November 26, 2011: Mars Science Laboratory, “Curiosity” launches. The rover will investigate whether conditions on Mars have been favorable for life.

December 5, 2011: The Kepler Mission announces its first exoplanet in a Sin-like star’s habitable zone.

JPL/ NASA Chronicles of Discovery: Timeline (1950s-1989)

Voyager 1

From: JPL/ NASA Timeline: Chronicles of Discovery

January 31, 1958: Built in just three months, Explorer 1 is launched as the first U.S. satellite; it discovers the Van Allen radiation belts.

March 3, 1959: Pioneer 4 launches and escapes Earth’s gravity to orbit the Sun.

August 27, 1962: Mariner 2 launches and conducts the first flyby of another planet when it visits Venus on December 14.

July 28, 1964: Ranger 7 launches and executes an intentional crash-landing into the Moon on July 31. As it closes in, it sends back more than 4,000 pictures of the lunar surface.

November 28, 1964: Mariner 4 launches with a destination of Mars.

February 17, 1965: Ranger 8 launches and impacts the Moon in Mare Tranquillitatis three days later. This location will become the landing spot for the Apollo 11 astronauts 4-1/2 years later.

March 21, 1965: Ranger 9 launches and three days later impacts the Moon in the 108-kilometer-diameter (67-mile) crater Alphonsus, sending back more than 5,800 images.

July 14, 1965: After an eight-month voyage to Mars, Mariner 4 makes the first flyby of the red planet. The spacecraft radios back the first close-up photos of another planet.

May 30, 1966: Surveyor 1 launches. On June 2, it becomes the first U.S. spacecraft to make a soft landing on the moon.

April 17, 1967: Surveyor 3 launches, lading on the Moon on April 20. Two and a half years later, the Apollo 12 astronauts will land nearby and photograph the Surveyor 3 site.

June 14, 1967: Mariner 5 launches and flies by Venus on October 19.

September 8, 1967: Surveyor 5 launches and lands on the Moon September 11.

November 7, 1967: Surveyor 6 launches and soft-lands on November 10. The lunar mission runs until December 14.

January 7, 1968: Surveyor 7, the last of the Surveyor series, launches and soft-lands on the Moon on November 9. Overall, the Surveyors acquire 90,000 images from five sites on the Moon.

February 24, 1969: Mariner 6 launches. A month later, on March 27, Mariner 7 launches. They complete the first dual mission to Mars with flybys on July 3 and August 5.

May 30, 1971: Mariner 9 launches and reaches Mars on November 13, becoming the first spacecraft to orbit another planet. The craft operates for nearly a year around Mars.

November 3, 1973: Mariner 10 launches on a mission to Mercury and Venus, the first craft designed to visit two planets.

February 5, 1974: Using gravity-assist for the first time, Mariner 10 swings by Venus to borrow the planet’s gravity to propel it on to Mercury, which it passes on March 29. On September 21, it flies past Mercury again.

March 16, 1975: Mariner 19 flies by Mercury a third time.

August 20, 1975: Viking 1 launches an orbiter and lander toward Mars. On September 9, Viking 2 launches a similar orbiter- lander pair.

June 19, 1976: Viking 1 arrives in orbit at Mars. On July 20, its lander becomes the first craft to soft-land on another planet. On August 7, Viking 2 arrives in orbit, and its lander touches down on September 3.

August 20, 1977: Voyager 2 launches, followed by the launch of Voyager 1 on September 5.

June 26, 1978: The experimental Seasat satellite launches to test four instruments that use radar to study Earth and its seas. The satellite collected more ocean topography data than the previous 100 years of shipboard research.

March 5, 1979: Voyager 1 makes its closest approach to Jupiter. On July 9, Voyager 2 flies by the giant planet. Together, the Voyagers take more than 22,000 images of Jupiter and its moons.

November 12, 1980: Voyager 1 flies by Saturn.

August 25, 1981: Voyager 3 flies by Saturn.

October 6, 1981: The Solar Mesosphere Explorer launches to study processes that create and destroy ozone in Earth’s upper atmosphere.

November 12, 1981: The first in a series of radar imagers is launched on the space shuttle.

January 25, 1983: The Infrared Astronomical Satellite launches into Earth orbit. The telescope discovers solid material around distant stars, strongly suggesting the existence of planets.

October 5, 1984: The second in a series of imaging radar missions launches on the space shuttle.

January 24, 1986: Traveling to a planet more distant than any visited before, Voyager 2 makes the first ever flyby of Uranus, nearly 3 billion kilometers (1.8 billion miles) from Earth. Voyager images 15 of Uranus’ moons.

May 4, 1989: Magellan launches a mission to Venus.

August 25, 1989: Voyager 2 is the first spacecraft to fly by Neptune.

October 18, 1989: Galileo launches on a six-year journey to Jupiter.

Modern Astronomy: 1500-1800

Modern Astronomy (1500 – 1800 A.D.)

Nicolaus Copernicus

Nicolaus Copernicus (1473-1543)

The Polish astronomer Nicolaus Copernicus advocated the heliocentric view, calculated distances to planets and period of planets, and explained the retrograde motion. Before his death in 1543, Copernicus revolutionized astronomy by publishing his work,  De revolutionibus orbium coelestium (On the Revolutions of the Celestial Spheres).

Heliocentric Theory

Tycho Brahe

Tycho Brahe (1546-1601)

The Danish astronomer Tycho Brahe made accurate measurements of planetary positions by using a “quadrant.”

Astronomers Using a Quadrant

Johannes Kepler

Johannes Kepler (1571-1630)

As Tycho Brahe’s student, Johannes Kepler received his teacher’s measurements when Brahe died in 1601. In 1610, Kepler then derived the three laws of planetary motion using Brahe’s measurements and empirical rules. Instead of the circular orbits that Copernicus advocated, Kepler discovered that the planets and stars traveled in elliptical orbits.

Kepler’s 1st Law

Kepler’s 1st Law (1609) The planets move around the Sun in ellipses, having the Sun at one of its foci.

Ellipse: 1) each orbit has a shape and a size; 2) the eccentricity (e = 1- B/A) describes how elongated the ellipse is; 3) the size is described by the semi-major axis (2A); 4) when B=A, the orbit is circular and e=0 (eccentricity ranges from 0 to 1, with 1 as the most eccentric)

Kepler’s 2nd Law

Kepler’s 2nd Law (1609)/ Law of Equal Areas: Each planet revolves in such a way that the line joining it to the Sun sweeps over equal areas in equal time intervals

Kepler’s 3rd Law (1618)/ Harmonic Law: The square of the period of revolution is proportional to the cube of the average distance of the planet to the Sun (P²=A³, where P = the period in years and A = the semi-major axis of an orbit in AU)

Consequence: Distant planets take longer to orbit the Sun and travel at slower speeds

Galileo Galilei

Galileo Galilei  (1564-1642)

Italian astronomer Galileo Galilei, the “father of modern science,” was the first to use the telescope to observe the Moon, Jupiter and its moons (Io, Europa, Ganymede, and Callisto), Saturn, and phases of Venus. His observations supported the heliocentric view. After making the telescope in 1609, Galileo observed mountains on the Moon and discovered the Galilean moons of Jupiter. While Ptolemy thought Venus will always appear as a “crescent” and never as a full circle, Galileo discovered that Venus appears in phases. However, Galileo, deemed a heretic by the Roman Catholic Church Inquisition in 1615, was placed under house arrest for the rest of his life.

Isaac Newton

Isaac Newton (1642-1727)

LIFE & ACHIEVEMENTS: English physicist Isaac Newton, often known as the greatest and most influential scientist who ever lived, revolutionized astronomy and physics with his three laws of motion and law of universal gravitation. Born in 1642 (Galileo’s death) and into a world of mysticism, Newton was the last philosopher/ scientist. Newton derived Kepler’s three laws of planetary motion, invented calculus, and answered fundamental questions about the nature of light, motion, and time. Still, with all his achievements, Newton invented a new kind of telescope, studied theology, alchemy, and chemistry.

THE WORLD AROUND NEWTON: At the time, “gravity” meant solemn and was a mood, not a force. People believed that the world was not “solvable.” Light and heavy things separated themselves “naturally.” Time was hard to separate and the concept of motion was not well-defined. Philosophers/ scientists constrained motion to: pushing, pulling, carrying, twirling, combining, separating, waxing, and waning. Aristotle had defined things “in motion” as: an apple ripening, a dog running, a child growing up, and a spinning top.

EARLY LIFE: At Cambridge University, Aristotle was the sole authority on logic, ethics, rhetoric, cosmology, and mechanics. Because his tutor was a linguist, Newton mostly studied on his own. Born poor, Newton conserved paper costs by writing in a tiny font.

ROAD TO DISCOVERY: While Galileo had discovered uniform acceleration (all bodies fall at the same rate), Newton asked: How and why does something’s velocity change? In 1664, the plague in England caused Cambridge to close down, but Newton continued to discover fundamental ideas in astronomy and physics. By first reading works such as Euclid’s “Elements” and that of Descartes, Newton explored the concept of infinity, curvature, and the rate of the bending of lines, trajectories. “To resolve problems of motions,” Newton then invented calculus. To explore the nature of light, Newton used a prism to “isolate” blue light and passed the blue light through a second prism; the light stayed blue. Newton discovered that prisms only separate color and white light was “made up of” different colors. Furthermore, light comes from the Sun in eight minutes, the Moon tugs at the Earth to create waves, and the same Universal Laws exist throughout the Universe.

IMPACT: Newton defined these concepts: “mass,” “action,” “reaction,” “momentum,” “inertia,” “to feel the force of gravity.” He quantified the world with calculus and made people Newtonians (think that the world is solvable). Starting from the Newtonian Age, scientists linked mathematics and science to prove facts and claims.

Law of Universal Gravitation: Every particle in the Universe attracts every other particle with a force proportional to the product of their mass and inversely proportional to the square of the distance between them.

Gravity = the force between two objects that depends on the objects’ masses and on the distance between them

  • Gravity is a mutual force acting on both bodies
  • The force on each body is t he same size, but in opposite directions

Newton’s 1st Law/ Law of Inertia: Every material object continues in its state of rest, or of motion in a straight line, unless it is compelled to change that state by external forces. In other words, a stationary object will stay at rest, while a moving object will stay in constant motion unless an unbalanced force acts on it. “Constant” motion = at a constant speed and a constant direction.

Inertia = the resistance of any physical object to its state of motion or at rest

Balanced Forces = Forces cancel one another and no change in motion results (e.g. sitting in a chair)

Unbalanced Forces = One force is greater than another, causing a change in motion (e.g. jumping off a diving board)

Speed and Velocity = Velocity combines the speed of an object and the direction of motion and is equal to the change in distance over change in time (V = d/t) (e.g. speed = driving 60 miles/ hr; velocity = driving 60 miles/hr east)

Newton’s 2nd Law: The acceleration of an object is directly proportional to the net force acting on it

Acceleration = a change in velocity; objects of different masses on earth fall at the same rate

Newton’s 3rd Law

Newton’s 3rd Law: For every action there is an equal and opposite reaction.

Forces and Orbits: For objects in uniform circular motion, the force of gravity is perpendicular to the motion, the object orbits at constant speed, gravity changes the direction only of the motion, and there is still an acceleration.

Elliptical Orbits: For planets in elongated orbits, gravity changes both the direction and the speed of the planet, the planet slows down as it moves away from the Sun, and the planet speeds up as it approaches the Sun

Gravity Depends on MassF gravity = G x (m1m2)/r², where m1 and m2 are the masses of the two objects, r is the distance between the two masses, G is Newton’s gravitational constant (6.7 x 10-¹¹ m³kg s²)

Newton’s Derivation of Kepler’s Laws Using His Law of Gravitya1 = F gravity/ m1 = G x m2/r²; accelerations are smaller for objects far from the Sun (when r is large)

Newton’s Derivation of Kepler’s 3rd LawP² = [( 4∏ )/ G (m1 + M2)] (R³)

Early Astronomy History: Timeline

EARLY HISTORY (2700 B.C. – 1600 A.D.)

Early Astronomy: Predicting Eclipses, Determining Equinoxes and Solstices

2700 B.C. (Stonehenge, England) – stones marked solstices and equinoxes; Aubrey holes predicted eclipses

2000 B.C. [Sumerians] – earliest constellations (bull, lion, scorpion); base 60 system

2000 B.C. [Babylonians] – Pythagorean Theorem

1000 B.C. [Egyptians] – helical rising of Sirius; 12 month, 30 day calendar; sundial

1000 B.C. [Chinese] – counting boards

700 B.C. – 50 A.D. [Babylonians] – planetary positions and eclipses

600 B.C [Pre-Greek: Thales of Miletus] – solar eclipse prediction, Saros Cycle; constellations as known today

600 B.C. (Miletus, Greece) [Anaximander] – shadow from stick t calculate the length of the year; life originated in water, evolved from simpler forms

500 B.C [Pythagoras of Samos] – spherical moon, spherical-moving Earth

450 B.C [Empodocles] – water thief to argue that air must be so finely divided that it’s invisible

400 B.C. [Chinese] – sunspots

400 B.C. [Democritus] – atoms, large number of other worlds, Milky Way aggregates of light from other galaxies

4th Century B.C [Plato] – proposed Uniform Circular Motion of Planets; spherical Earth

350 B.C. (Athens, Greece) [Aristotle]– model of the solar system: spherical universe centered on solid spherical Earth (geocentric view); moon between Earth and Sun; all objects are from the four elements – earth, water, fire, and air; earth and heaven to be subject to two different sets of laws

300 B.C. (Alexandria) [Euclid] – most prominent mathematician; “Elements”: geometry; conic sections

310-250 B.C. [Aristarchus of Samos] – relative distances and sizes of the Moon and the Sun; Sun at the center of the solar system (heliocentric view); used Earth’s shadow to measure the size of the moon

200 B.C. (Alexandria) [Eratosthenes] – measured earth’s size using simple geometry and scientific process

130 B.C. [Hipparchus of Rhodes] – star maps; star catalog of 850 stars, precession; epicycles

150 A.D. [Ptolemy] – fixed Aristotle’s model with the epicycle theory: planets move in epicycles (small circular paths around which the planets move); the centers pf epicycles are along the deferent (big circle)

250 A.D. [Mayans] – “place-value” number system

500 A.D [Hyptia] – first known woman astronomer, librarian of Alexandria

500 A.D. [Chinese] – solar wind; comets: tail of comets always point away from the Sun

6th – 9th Century A.D. [Persian and Arabic Astronomy] – “Al-Sufi”: Book of Stars Showing Orion Nebula; “Al-Battani”: Non-circularity of Earth’s Orbit

10th Century A.D. [Mayans] – Dresden Codex, Venus tables, eclipse tables

10th Century A.D. [Chinese] – star map showing 26 sections

1054 A.D. [Chinese] – supernova: remnant traced to Crab Nebula

1100 A.D. [Pueblo Native Americans] – Sun Dagger

1270 A.D. [Samarkand] – star catalog

Mid-1400’s A.D. (Germany) [Regiomontanus] – “Ephemeris”; “The Nuremberg Chronicle” – planetary positions and comet charts

Prehistoric Astronomy

Prehistoric Astronomers

As one of the oldest sciences, astronomy flourished in prehistoric times. Hunter-gatherers realized the importance of recognizing seasons, moon phases, annular events, and the apparent movement of the Sun. The early peoples divided the skies into the North Celestial Pole, a single point about which stars move around in the sky, and the South Celestial Pole. The Celestial Equator is the half-way line between the Celestial Poles and also a projection of Earth’s equator into the sky. 3,000 years ago, the Babylonians discovered the 360° circle, which is a base 60 system that originated from 365 days in a year. The five ancient planets are Mercury, Venus, Mars, Jupiter, and Saturn. The North Star is the star closest to the North Celestial Pole— currently Polaris. Because of precession, or the wobble of Earth’s rotational axis that sweeps out a circle in 26,000 years, the extension of Earth’s North Pole points to a different North Star during the motion. Helical rising is the first day each year when a particular star can first be seen just before dawn; helical setting, then, is the last day of the year when the star can be seen at dusk.  The ecliptic is the apparent path of the Sun in the sky and the zodiac is the path of planets within a zone of 18 degrees wide-centered on the ecliptic. Hunter-gatherers and early settlers utilize knowledge of these ideas to farm, navigate, and survive.