Ancient sites like Newgrange Passage Tomb and Stonehenge were carefully aligned with astronomical events like solstices and equinoxes, suggesting their builders had knowledge of the movement of celestial bodies. Early models of the universe placed Earth at the center, with the geocentric model proposed by Aristotle and later displaced by Copernicus' heliocentric model placing the Sun at the center. Kepler later improved on this by discovering planetary orbits were elliptical rather than circular in shape.

1. Views on the Nature of Earth & Space

2. How can this help us on Earth?

3. TrackingCosmologicalEvents
Solstice:
• The word comes from Latin - Sol=sun stice=stop
• Longest and shortest days of sunlight during the year.
In the Northern hemisphere the summer solstice happens ​around June 21 and is
the longest period of daylight. This ​marks the first day of summer. The winter
solstice happens around December 21 and is the ​shortest period of daylight. This
marks the first day of winter.
Equinox:
• The word comes from Latin - Equi=equal nox=night
• 2 Days of the year where there is equal daylight and night during the year.
In the Northern hemisphere the spring equinox happens ​around March 21 and the
fall equinox happens around September 21

4. TrackingCosmologicalEvents

5. ​NewgrangePassageTomb
The oldest site that has definite astronomical
connections is ​Newgrange Passage Tomb in Ireland
that dates from about ​3,200 B.C.
For about 2 weeks on ​either side of the winter ​solstice,
light passes ​through a roof box ​above the
entrance ​passage. This incoming ​light causes the
entire ​central passageway to ​be illuminated. Many of ​the
stones that make up ​Newgrange are ​decorated with
symbols ​that look like the sun.

6. Stonehenge
The most famous English ​site for
Neolithic ​astronomical use
is ​Stonehenge. The main ​stones of the
site date from ​about 3,000 B.C.
Some ​people believe that the
clear ​alignments of the stones with ​the
sun and the moon allowed ​the Druids
who built it to ​predict solar and
lunar ​eclipses. However, most ​people
believe that the site ​had some
religious ​importance attached to it ​rather
than an astronomically ​predictive value.

7. MedicineWheel
The Medicine Wheel’s large
circle measures 213
feet ​around. The 28 spokes
radiating from its center
represent ​the number of days in
the lunar cycle. Six
spokes ​extending well beyond
the Wheel are aligned to
the ​horizon positions of sunrises
and sunsets on the first ​days of
the four seasons.

8. AncientViews
Ancient monuments had a view that put the Earth at rest in the ​center of the
Universe.
 The Egyptians saw the sky as the arched body of ​the goddess Nut
 The Hindus saw the sky resting on the tusks of an immense elephant
 The Babylonians saw the sky as the inside of a huge ​bell jar
 The Arabs more recently saw the sky as an immense tent.
There were many views of the Earth’s position, however very ​few of these
descriptions suggested that the Earth actually ​turned.

9. GeocentricModel
Geocentric Model: proposed by Aristotle
that ​Earth is at the center, surrounded by the
Sun, the ​Moon and the five planets known at
the time. It also ​had stars that were fixed to
the outermost sphere.
The geocentric model allowed early
astronomers to forecast such events as the
phases of the Moon, but it still could not
explain many other observations. For
example, why did Mars, Jupiter, and Saturn
sometimes seem to loop back opposite to
their usual movement across the sky?

10. HeliocentricModel
Heliocentric Model: proposed by
Nicholas ​Copernicus and had the Sun at the center,
surrounded ​by Earth and the other planets. It also
had stars that ​were fixed to the outermost sphere.
A little less than 100 years later, a new generation of
scientists—with the help of a major technological
invention, the telescope—provided solid evidence
for Copernicus’s theory. Notable among these
scientists was the renowned Galileo Galilei of Italy.
Even though Galileo’s discoveries added credibility
to the Copernican ideas, the model could still not
predict planetary motion very accurately.

11. HeliocentricModel
Heliocentric Model: proposed by
Nicholas ​Copernicus and had the Sun at the center,
surrounded ​by Earth and the other planets. It also
had stars that ​were fixed to the outermost sphere.
A little less than 100 years later, a new generation of
scientists—with the help of a major technological
invention, the telescope—provided solid evidence
for Copernicus’s theory. Notable among these
scientists was the renowned Galileo Galilei of Italy.
Even though Galileo’s discoveries added credibility
to the Copernican ideas, the model could still not
predict planetary motion very accurately.

12. Ellipses
A German mathematician, Johannes Kepler, came up with the next solution to the
puzzle. Using detailed observations of the movement of the planets (observations
carefully recorded by the great Danish astronomer, Tycho Brahe), Kepler discovered
what was missing from the Copernican ideas. The orbits of the planets, he realized,
were ellipses and not circles.
Ellipse: The shape in
which planets orbit.
Similar to an oval shape