The History of Astronomy

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The History of Astronomy http://www.ichundmeinmitbewohner.

1 The History of Astronomy Mauna Kea Observatories, HI

2 Astronomy Through The Ages Astronomy is a very old science. Chemistry really didn t get going in earnest till at least the 1700s. Biology had its biggest early discoveries in the 1800s. Physics took off in the 1900s (Newton notwithstanding). But astronomy just look up and there it is. We ve been doing this for a long time.

3 Early Man Some of the earliest evidence of mankind s interest in the sky comes from drawings like the Pueblo Petroglyphs. Drawings of eclipses, comets, and supernovae have been uncovered. Generally speaking, however, early man had little to do with astronomy.

4 The Babylonians The Babylonians (~1600 BC) are among the first to actually record stuff. Positions of planets, times of eclipses stuff like that.

5 The Greeks The Greeks (the Hellenistic Culture; ~500 BC) inherited the astronomical records of the Babylonians and started to move things forward. They began to construct a cosmological framework. The sky began to move from just a tool for navigation and other practical things to a source of experimentation and exploration. They even knew the Earth was spherical, since the shadow of the Earth on the Moon was always circular.

6 The Greeks What s more, the Greeks took note that seven celestial objects moved, unlike the background stars. They called them planetes ( wanderers ) and we have since named our days of the week after them you may need to think of their Romance language words: The Sun (Sunday) The Moon (Monday) Mars (Tuesday Day of Mars) Mercury (Wednesday Day of Mercury) Jupiter (Thursday Day of Jupiter) Venus (Friday Day of Venus) Saturn (Saturday Day of Saturn)

7 Planets of the Week

Aristarchus (310-230 BC) Aristarchus of Samos was an ancient Greek astronomer. He figured out the relative sizes of the Earth, Moon, and Sun.

8 Aristarchus ( BC) Aristarchus of Samos was an ancient Greek astronomer. He figured out the relative sizes of the Earth, Moon, and Sun. Given that the Earth was found to be much smaller than the Sun, the Earth must revolve around the Sun. Aristarchus of Samos (ahead of his time)

9 The Greeks Thales (~480 BC) became the first to predict eclipses using information dating to the Babylonians. Eratosthenes (~220 BC) became the first to measure the circumference of the Earth, and the way he did it is truly awesome: TED: Adam Savage How Simple Ideas Lead to Scientific Discoveries

10 Aside: Geometry Geo- is the stem word for Earth stuff, right? Geography is the study of locations on Earth. Geology is the study of the abiotic Earth. Geometry is math with shapes wait, what? Turns out, geometry literally means Earth measure and comes from Eratosthenes observations.

Ptolemy (AD 90-168) No one knows much about this Ptolemy dude. What s best-known about Ptolemy is that he first popularized the idea of a geocentric solar system. Geocentric = Earth-centered.

11 Ptolemy (AD ) No one knows much about this Ptolemy dude. What s best-known about Ptolemy is that he first popularized the idea of a geocentric solar system. Geocentric = Earth-centered. He put this forth in his work Almagest and it took until the 1500s for Nicolaus Copernicus to set the record straight. The catch? The Catholic Church kinda got attached to the whole geocentric thing. Ptolemy PSM_V78_D326_Ptolemy.png

12 The History of Astronomy In what today is England, early astronomers built Stonehenge around 2,500b.c. Stonehenge appears to be a rather primitive computer for determining the position of the planets and the Sun. Which in turn provided the native people with the ability to plan their seasonal pagan shindigs. On the summer solstice, the Sun lines up with some of the stones perfectly.

13 The History of Astronomy Islamic astronomers contributed to astronomy many names for bright stars, words like zenith, and, notably, algebra.

14 The Mayans El Caracol ( the snail named for a spiral inner staircase) is an observatory in Mexico built by the Mayans. Its windows line up perfectly to view Venus, in which the Mayans took great interest. Notably, the Mayans (and Chinese) were very good at predicting eclipses despite having different calendars than we use today.

Native Americans Bighorn Medicine Wheel, in the Bighorn Range of Wyoming, lies at elevation 9642. It s a wheel, 80 in diameter, constructed out of stones 300-800 years ago.

15 Native Americans Bighorn Medicine Wheel, in the Bighorn Range of Wyoming, lies at elevation It s a wheel, 80 in diameter, constructed out of stones years ago. At end of each of the spokes are large stones, and each stone denotes a location where an important constellation rises or where the Sun rises during the summer solstice.

16 The Invention of the Telescope Hans (Johan) Lippershey is generally regarded as the inventor of the first telescope. His patent application (which was denied by the government of Belgium) was submitted in Hans Lippershey

Nicolaus Copernicus (1473-1543) Copernicus set forth the idea of the heliocentric solar system in De Revolutionibus. Heliocentric = Sun-centered.

17 Nicolaus Copernicus ( ) Copernicus set forth the idea of the heliocentric solar system in De Revolutionibus. Heliocentric = Sun-centered. This was the beginning of the Copernican Revolution. Copernicus dedicated the book to Pope Paul III and knew he was going to cause some trouble. His weakness? He insisted orbits were circular. Nicolaus Copernicus

Galileo Galilei (1564-1642) Galileo made his own telescope He saw Venus going through various phases, along with moons orbiting Jupiter (not Earth) so why should Earth be the center of it all?

18 Galileo Galilei ( ) Galileo made his own telescope He saw Venus going through various phases, along with moons orbiting Jupiter (not Earth) so why should Earth be the center of it all? In addition, he observed sunspots directly, which led to complete blindness late in life. So Galileo supports the Copernican System, which by this point had been labeled as heresy by the Church. Cue the Inquisition Galileo Galilei

19 Galileo s statements erupted into a big mess in 1633 after he published a book championing the Copernican System. As a result, Galileo was under house arrest for eight years, dying in captivity at age 77, completely blind. It took until 1992 for the Pope/Vatican to formally excuse Galileo for being correct. The Galileo Mess

Tycho Brahe (1546-1601) Tycho Brahe (pronounced Tieco Bra-hey ) made his observations from Hveen Island in Denmark.

20 Tycho Brahe ( ) Tycho Brahe (pronounced Tieco Bra-hey ) made his observations from Hveen Island in Denmark. He s credited for having some of the most accurate observations of the position of the stars and planets. Tycho Brahe

Tycho Brahe (1546-1601) Pretty cool, except despite knowing of Copernicus s discoveries, he believed the Sun revolved around the Earth, and the rest of the planets revolved around the

21 Tycho Brahe ( ) Pretty cool, except despite knowing of Copernicus s discoveries, he believed the Sun revolved around the Earth, and the rest of the planets revolved around the Sun. He still couldn t see parallax in the stars. That was detected in the 1800s. Brahe s model still explained the phases of Venus as confirmed by Galileo. Brahe s Naked-Eye Observatory

22 The Tychonic Solar System

Johannes Kepler (1571-1630) Upon Tycho s death, his data were inherited by his student, Johannes Kepler.

23 Johannes Kepler ( ) Upon Tycho s death, his data were inherited by his student, Johannes Kepler. Kepler is perhaps best known for Kepler s Laws of Planetary Motion in which he stated the planets have an elliptical orbit (not circular). He also subscribed to the correct heliocentric model of the solar system. Johannes Kepler

Isaac Newton (1642-1727) Known perhaps best for his laws of motion, Newton helped kickstart the field of astrophysics.

24 Isaac Newton ( ) Known perhaps best for his laws of motion, Newton helped kickstart the field of astrophysics. For now, Newton s other accomplishments include the invention of the reflecting telescope and the publication of Principia, which forever changed the scientific landscape. Isaac Newton

Christiaan Huygens (1629-1695) Christiaan Huygens ( Hi-youghens ) confirmed that Saturn was a ringed planet and

25 Christiaan Huygens ( ) Christiaan Huygens ( Hi-youghens ) confirmed that Saturn was a ringed planet and also spotted its moon Titan. Christiaan Huygens

Giovanni Cassini (1625-1712) Cassini used the parallax method to estimate the distance to Mars.

26 Giovanni Cassini ( ) Cassini used the parallax method to estimate the distance to Mars. Others had made somewhat similar measurements, but mostly with the Moon and Sun, so Cassini is starting to give dimension to the solar system. Other discoveries included a more accurate latitude/longitude method that gave a better estimation of the size of France. Cassini also discovered four moons of Saturn, a slight gap in the rings of Saturn, and the Great Red Spot on Jupiter. Giovanni Cassini

Cassini-Huygens Spacecraft Today, a spacecraft currently exploring Saturn (launched in 1997, has been there since 2004) is named after, well, Cassini and Huygens.

27 Cassini-Huygens Spacecraft Today, a spacecraft currently exploring Saturn (launched in 1997, has been there since 2004) is named after, well, Cassini and Huygens. Among its many notable discoveries is that Enceladus, a moon of Saturn, has an underground ocean of liquid water. Moons of Saturn as seen by Cassini-Huygens: Rhea (front), Titan (rear)

28 A Photo From the Huygens Probe The surface of Saturn s moon Titan:

29 William Herschel ( ) Herschel (and his sister Caroline) discovered Uranus. In fact, Caroline Herschel was the first woman to discover a comet and ultimately found eight of them. William Herschel

William Herschel (1738-1822) Herschel has another thing to his credit: Not only was he the discoverer of Uranus, he was also the first to discover a planet. Huh?

30 William Herschel ( ) Herschel has another thing to his credit: Not only was he the discoverer of Uranus, he was also the first to discover a planet. Huh? Every other planet, up to and including Saturn, can be seen with the naked eye and has been known since ancient times. However, you need a telescope to see Uranus. (giggle) Why did Herschel name his planet Uranus? article How to Pronounce Uranus video William Herschel (wrong camera, buddy)

Aside: Discovery of Neptune With Kepler s and Newton s laws firmly established,

match what it should be, according to Newton s laws unless there was a massive

In 1845 Urbain Le Verrier calculated the likely location of that massive, more

31 Aside: Discovery of Neptune With Kepler s and Newton s laws firmly established, in 1781 Anders Johan Lexell computed Uranus s orbit and found that it didn t match what it should be, according to Newton s laws unless there was a massive planet behind it. In 1845 Urbain Le Verrier calculated the likely location of that massive, more distant planet.

It was the night of September 24, 1846, and Neptune was less than 1 from its predicted location. http://upload.

32 Heinrich Louis d Arrest Johan Gottfried Galle Aside: Discovery of Neptune Johan Gottfried Galle and his student Heinrich Louis d Arrest discovered Neptune in under an hour of searching, using Le Verrier s calculations. It was the night of September 24, 1846, and Neptune was less than 1 from its predicted location. JohannGalle.jpg

Edwin Hubble (1889-1953) Hubble is credited with having discovered that the universe is expanding.

33 Edwin Hubble ( ) Hubble is credited with having discovered that the universe is expanding. He worked with the largest telescopes in the world at the time and used them to discover much about extra-galactic objects (AKA deep space stuff). Edwin Hubble

35 The Pillars of Creation (Eagle Nebula)

36 Saturn from the Cassini spacecraft

37 Saturn from the Cassini spacecraft

Astronomy Through The Ages

Astronomy Through The Ages Astronomy is a very old science. Chemistry really didn t get going in earnest till at least the 1700s. Biology had its biggest early discoveries in the 1800s. Physics took off