In this chapter we discuss 1. the movement the planets around the Sun. 2. the movement of the Sun in the Galaxy. 3. Initial conditions.
In order to simulate this movement MERCURY is used.
Almost all the planets move approximate in a circle around the Sun, with the Sun in the centre. The only two exceptions are Mercury and Pluto. The trajectory of both planets is to a large extend an ellipse. The movement of Mercury will be studied in detail in the next chapter.
The Earth moves around the Sun in one year. By definition this movement is counter clockwise. For simplicity the trajectory of the Sun is considered a circle.
To observe this movement perform the program: MERCURY.TXT 4.1 TEST 2A
Our Sun is one of many stars in our Galaxy. The Sun does not stand still, it also moves. The Sun moves in through space in our galaxy in a great big circle.
To observe this movement perform the program:
The simulation shows that the duration of one revolution is 198 million years.
It is an open question if our Sun actual moves in a circle in our Galaxy. This could also be an ellipse and most probably it is.
In paragraph 2.1 we observed the movement of the Sun, assuming that the speed of the Sun is zero. Paragraph 2.2 showed that is not true: the Sun has a speed of approximate 200 km/sec related to the centre of our galaxy.
Our own galaxy as a whole also has a speed through space.
Literature 5 shows that the resulting speed of the Sun is: 19.7 + or - 0.5 km/sec
The movement of the Sun through space is described by two parameters: speed v and angle phi. The following drawing explains this.
P
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..B.. .
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. . .
. . .
. . Phi .
C.................... O ................... A
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. . .
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. . .
. . .
. ..D..
.
N
O = Sun
N O P = The line of the movement of the Sun
A B C D A = One revolution of the movement of the Earth
Phi = angle between the direction of the movement of the Sun and
the initial position of the Sun
Phi = 0 means Sun initially moves towards A
Phi = 90 means Sun moves along the line DOB
Phi = 180 means Sun moves away from A towards C
Phi = 270 means Sun moves along the line BOD
In the above figure the circle ABCDA represents one revolution of the Sun in one year.
To study this movement for speed of the Sun of 100 km/second perform the program:
What the test shows is that 1) for Phi = 0 (When the Sun moves initially towards the Earth) the time of one revolution is too long. 2) for Phi = 180 (When the Sun moves initially away from the Earth) the time of one revolution is too short.
The reason that for phi is 0 the revolutions are longer then expected is because in the initial state (in position A) the Sun moves towards the Earth. Gravity propagation takes time. That means the position where the Earth "feels" that the Sun is earlier i.e. towards the left. That means (initially) the distance is longer as it should be and the force between Sun and Earth too small. This in turn will mean that the Earth will move to slow i.e. the time of one revolution will be longer as expected.
The reason that for phi is 180 the revolutions are shorter then expected is because in the initial state (in position A) the Sun moves away the Earth. Gravity propagation takes time. That means the position where the Earth "feels" that the Sun is earlier i.e. towards the right. That means (initially) the distance is smaller as it should be and the force between Sun and Earth too large. This in turn will mean that the Earth will move to fast i.e. the time of one revolution will be shorter as expected.
To solve this problem the initial conditions are modified: for phi is 0 the distance between Sun and Earth is made smaller. for phi is 180 the distance between Sun and Earth is made larger. The amount in both cases is the same and equal to:
v * distance
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c
To study the movement for speed of the Sun of 100 km/second and with modified initial conditions perform the program:
What this simulation shows is that a simulation of n objects must be based on the position of those n objects at the same moment in absolute space.
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