1. The earth rotates from west to east around an axis passing through the north and south poles. This causes celestial bodies like the sun and moon to appear to move from east to west. Foucault demonstrated the earth's rotation through his pendulum experiment, showing the plane of the pendulum's swing shifts over time. 2. The earth revolves around the sun in an elliptical orbit. This causes the constellations visible at night to change depending on the season. The distance between earth and nearby stars changes slightly over the course of a year, demonstrating the earth's revolution around the sun. The earth completes one revolution, or year, around the sun every 365.2422 days.

1. 1. Earth's rotation:
Earth rotates from which direction? The earth rotates from west to east around a straight line
passing through the north and south poles. Therefore, it seems that celestial bodies such as the
sun and the moon are turning from east to west.
Galileo said in the 17th century that the earth was spinning, but he couldn't believe it.
Evidence of the Earth's Rotation
French physicist Foucault (1851) made a 67m long pendulum on the dome of the temple and
experimented with evidence of the Earth's rotation.
I observed the pendulum by gently shaking it on one vibrating surface.
If no force is applied from the beginning, the vibration surface should be the same, but the
vibration surface changes over time.

2. I explained that this is because the direction of the ground changes because the earth rotates.
The Foucault pendulum is at the entrance to the National Science Museum. First, I checked the
direction of the vibrating surface, and after the tour, I checked the vibrating surface on the way
back and found that it had changed.
There are various other evidences that the earth is rotating, but I will omit it.
Earth's Rotation Period:
The Earth's rotation period can be found by examining the time it takes for a star to pass south
and come to the south the next day.
It takes about 23 hours, 56 minutes and 4.1 seconds, which is called one sidereal day.
The 24 hours a day we use every day is the time it takes for the center of the sun to pass through
the south and the next day.
There is a difference of about 4 minutes. This is because the earth revolves around the sun.
2. Revolution of the earth:
The constellations that can be seen at night change depending on the season. This is because the
earth orbits the sun (revolution).
The daytime sky with the sun is bright and the constellations are not visible, but it indicates that
the sun is moving between the constellations.

3. Evidence that the earth is revolving
The distance between the earth and the sun is about 150 million km.
When the earth is in position A and when it is in position B, the direction in which nearby stars
can be seen changes with a cycle of one year. This is evidence of the revolution of the earth.
The angle p in the figure is called the annual parallax . Since the stars are far away, the annual
parallax is a very small angle.
Even the closest star to the solar system, Alpha Centauri (4.4 light-years), has only 0.742 ". 1" is
1/3600 of 1 °.
Orbital period and solar calendar of the earth The earth goes around the sun in 365.2422 days
per year. This can be obtained by observing stars.
The rough orbital period of the earth can be known from the change of seasons.
In Egypt, the Nile rivers hang out in the same season, so from the average we knew that a year
was 365.25 days.
In 46 B.C.E., Julian of Rome created the Julian calendar with a normal year of 365 days and a
leap year of 366 days once every four years .
(365 + 365 + 365 + 366) ÷ 4 = 365.25 days: 1 year of the Julian calendar
365.25-365.2422 = 0.0078 days: Error of the
Julian calendar One year is too many 0.0078 days. After using the Julian calendar for about 1600
years, the calendar and the season are off by about 10 days.

4. 1582 AD Pope Gregory XIII is currently in use except for 10 days from the calendar made the
Gregorian calendar .
The day after October 4, 1582 AD was set to October 15, excluding 10 days. Since it is an
operation on the calendar, there is no need to worry about the date of birth being lost.
The Gregorian calendar has been devised to reduce 3 days in 400 years, and the average for one
year is 365.2425 days, which is 0.0003 days more for one year.