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WEEK 1: CELESTIAL SCIENCE |
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Name: |
◯ HE-
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◯ HE-
B |
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BEGIN
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THE GREEKS
KNEW THAT THE EARTH IS SPHERICAL. |
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EXAMPLES/APPLICATIONS/EXPLANATIONS |
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“Greek philosophers believed that
the Earth was round.” For centuries, many ancient scholars from India, China, the Middle
East, and Europe would continue to posit a vast array of incorrect models for
the Earth’s shape. Several prominent Greek philosophers of the 5th and 6th century
BC argued in favor of a curved disc or cylinder. 1.
Pythagoras - first to originate the
idea of a spherical Earth. At around 570 BC, for aesthetic grounds because Greeks, believe that the sphere
is the most perfect shape. He influenced others like a.
Plato - who
learned from the Pythagorean
community in Southern Italy. He founded his school in Athens
and taught his students that the Earth was round. In his dialogue book Timaeus, he wrote about the
properties of the universe, stating that the Earth was in the form of
a globe. b.
Aristotle,
provided more details about Earth. In his work of 350 BC entitled “On The Heavens,” he laid out
his astronomical theory of a geocentric
universe with a fixed spherical Earth at its center. 2.
a.
In summer solstice in Alexandria, Eratosthenes
noticed that a well it was NOT fully lighted since a shadow at the bottom of
a well is formed. b.
c.
Consequently, he found out that there on the same
day of the summer solstice there was no shadow in a corresponding well in Syene. d.
Using runners, the distance from Syene to
Alexandria, and with a geometry, measured the earth to be 5000 stadia or about 47,000
km. Actually its just 40,000 km, but
considering that time, it’s a brilliant achievement. |
References: https://mobygeek.com/features/greek-philosophers-round-earth-11725 https://www.britannica.com/biography/Tycho-Brahe-Danish-astronomer |
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 Figure 3 Among the Greeks, it was claimed that Pythagoras first to originate the idea of a spherical Earth 10 Observations We
Know That Earth Is Spherical 1) Ships and the horizon - The horizon
is the line at which the Earth’s surface and the sky appear to meet. When
ships sailing away disappear into the horizon. 2) We cannot see very far away - You
can see the moon and the sun which are much farther but not your neighboring
islands or countries. 3) Visibility and elevated areas - Higher
areas of land are visible at greater distances than low lying lands. 4) Other planets are spherical - Mercury,
Venus, Mars, Jupiter and Saturn can all be seen with the naked eye. In a
telescope, Uranus and Neptune are spheres too. If the other planets in our
solar system can be observed to be spherical, why should ours be any
different? 5) Most things are spherical - Not
only are planets spherical, but so are stars, some asteroids and moons. In
fact, the forces of nature are such that objects tend to form into spheres,
like dewdrops. 6) Temperature gradient from equator to
poles – Why do we have different climates on different areas. It only
means some part of the earth are less exposed to the sun than other parts on
different times of the year. 7) Days on same dates do not have the same
length – for the same reason as number 6. People live on different areas
of the earth that are not exposed to the same sunlight. 8) Shadows of sticks - Sticks placed
vertically in the ground at distant locations have shadows of different
lengths. 9) Tides - The moon’s gravitational pull
causes the oceans to bulge out in the moon’s direction. The bulge occurs on
both the side facing the moon and the opposite side. 10) Earth’s shadow - During a lunar
eclipse, the sun, Earth, and the moon are aligned such that the Earth’s
shadow falls onto the moon. The Earth’s shadow has been observed to be curved
as the planet is (curved). |
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PRE-TELESCOPE CELESTIAL PHENOMENA KNOWN TO
ASTRONOMERS |
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TOPIC |
EXAMPLES/APPLICATIONS/EXPLANATIONS |
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1.
Eclipses – the
phenomena in which either the moon or earth cast shadows on each other. a.
Solar Eclipse – the solar eclipse is the more
popular version of eclipse. This phenomenon occurs when the moon passes
across the sun’s disk and casting its shadow on the earth – producing
temporary darkness on certain parts of the earth. b.
Lunar eclipse – This happens when the moon passes
across the earth’s shadow. 2.
Comets - this
celestial phenomenon happens when a comet approaches the sun, and for a
period of time, the comet and its tail gets illuminated by the sun and
therefore, becomes visible on the earth’s night side. 3.
Planets,
Asteroids – The
planets were thought originally as stars but unlike stars, they do not stay
on the same position relative to other stars. This means that if a planet is
found in a constellation, it doesn’t stay there long enough (unlike stars,
which are fixed in their position on a constellation), 4.
Supernovas – The Chinese and Europeans were
among the first to document the presence a very bright star briefly
outshining other stars then dimming later. These short-period burst of light
from stars are now known as exploding stars 5.
Meteors/Meteor
Shower – Some
meteor showers (and comets) have a certain regularity. Most meteor showers
are yearly while comets are rarer. These glowing bright balls of light were
called shooting stars.
Now we call them by the more scientific term – meteor. 6.
Auroras – These celestial events are
visible on northernmost and southernmost part of the world and they come on a
nightly basis on certain time of the year. It happens when the Sun’s coronal
emissions interact with the earth’s magnetosphere. |
(https://www.lifepersona.com/7-contributions-by-tycho-brahe-to-science-and-society)    . |
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HOW ASTRONOMERS VIEW THE SOLAR SYSTEM
BEFORE AND AFTER THE RENAISSANCE ASTRONOMERS (COPERNICUS, GALILEO AND KEPLER) |
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SCIENTIFIC CONTRIBUTIONS OF RENAISSANCE
SCIENTISTS AND ASTRONOMERS |
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CONTRIBUTIONS
OF TYCHO BRAHE |
CONTRIBUTIONS OF JOHANNES KEPLER. |
 1.
Supernova - In
1572, Tycho observed a new star in the constellation of Cassiopeia to which
he named nova stella and today we
know as Supernova. During the 18 months in which the new star was
visible, he made strict observations and measurements that and found that
there was no daily parallax between the star and the background of fixed
stars. This implied that the nova
stella was beyond the Moon and the Earth's orbit. 2.
Uraniborg
/ Castle of the
heavens - The last primitive astronomical observatory before the invention
of the telescope in 1608 and the first modern observatory hundred percent
financed by the government. Here is where he, realizes and develops most of
his observations and new astronomical instruments. 3.
Astronomical
measuring instruments - From that solar eclipse of 1560, Tycho sought the
precision of his observations, and excellence in the records of them. To
perform this task, he needed to apply and improve various astronomical
measurement instruments. 4.
1000+
stars - He measured the position of stars and planets with a high
degree of precision. This resulted in a stellar catalog of more than 1000
fixed stars. 5.
Refraction
of light - The refraction of star light was first perceived by Tycho
Brahe. He corrected the astronomical measurements of this effect and also
produced a complete table of it.  7.
Kepler,
Brahe's successor - We cannot speak of Tycho Brahe, without naming who
was his successor: Johannes Kepler (1571-1630) - one of the Most important
scientists in history. After Brahe's death, Kepler gained access to all the
information cache of Tycho, which allowed him to continue investigating, so
that he could come to state his three laws on the movement of the planets. |
 1.
He was
the first to publish a defense of the Heliocentric Model of Copernicus - His first
major astronomical work, Mysterium Cosmographicum (Cosmic Mystery) was
published in 1596. Mysterium, ot strengthened the Heliocentric ideas of
Copernican system. 2.
He found
that a planet moved at different speeds according to its distance from the
sun - Using the astronomical and planetary observations
of Tycho Brahe, Kepler discovered that Mars didn’t move in a perfect circle
around the sun, as was believed at the time. He stated this idea in the 2nd Law of Kepler = Law of
Equal Areas. 3.
Discovered
That Planets Move In Elliptical Orbits Around The Sun - Kepler
set about calculating the entire orbit of Mars, using the geometrical rate
law and assuming an ovoid orbit. In 1605, Kepler finally found that Mars
follows an elliptical path around the sun. He thus arrived at his first law of planetary motion: that
the planets orbit the sun in ellipses, with the sun at one focus. 4.
Astronomia
Nova Is One of the Most Important Books in Astronomy - Kepler
published his ten-year-long investigation of the motion of Mars in his most
renowned work Astronomia Nova (New Astronomy). This includes the first two of
the three principles known today as Kepler’s laws of planetary motion. The
ideas of gravitations were mentioned in this book. 5.
He
Discovered His Third Law of Planetary Motion While Writing Harmonices Mundi -
Published in 1619, Harmonices Mundi (The Harmony of the World) is a book in
which he attempts to find harmony in nature by explaining proportions of the
natural world in terms of music. He also mentioned the idea of an inertia. 6.
He Laid the
Foundation of Modern Optics - Johannes Kepler began his investigation of
the laws of optics in his work Astronomiae Pars Optica (The Optical Part of
Astronomy). It contains the inverse square law of intensity of light against
distance; reflection concepts by flat and curved mirrors; and modern astronomy
ideas in optics such as parallax, astronomical refraction and the apparent
sizes of heavenly bodies, correct workings of the human eyes. In another work
in optics, Dioptrice, was published in 1611 and it contained the concepts of
real vs. virtual images; upright vs. inverted images; and the effects of
focal length on magnification and reduction. 7.
He also improved the Refracting telescope with
his own version called the Kepler Telescope. (See Figure on the left) |
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WEEK 1: ASSESSMENT |
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Name: |
◯ HE-
A |
◯ HE-
B |
◯ EIM |
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1. Add two more reasons why
the earth is a sphere. Refer to the
website shown above for other reasons
2. Are there other celestial
phenomena nowadays that were not visible to human eyes since before the
invention of telescopes?
3. Galileo’s contribution to
astronomy is when he discovered the 4 satellites of Jupiter, the early
observations of the Saturn’s rings and the phases of Venus. Kepler’s work was
on planet Mars. In your own words, would Kepler also have discovered what
Galileo had? |
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END.
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