Discussions:
The distance of the stars can find in many different ways. The three methods all have some errors because there are some limitations.
The Limitations of the methods:
Method 1: (1.) When we try to measure an object we see there would be a problem of parallax. It is because there is a distance between left eye and right eye and when we focus on the close-‐distanced ruler, and tried to use it measure the object far behind, the measure will cause error. The image of left eye and the image of the right eye you see will not be the same, and this make the measurement can’t be accurate. (2.) Everyone’s eyesight will be different and this will cause the error, and the measurement will change if we change the observer. (3.) The size of the image you see decreases slower and slower as the distance increase, so this make the method can only be used for close distance objects. Method 3: (1.) The shortest distance between the Earth and Venus is not like the picture I draw. There are still five more factors need to be add for finding the orbit, but the factors do not fit in my equation. Method 4: (1.) The gravity force and Centrifugal force is not balanced. There are still many other force will affect the calculations. For example, the gravity force of other planets. (2.) The Earth has its own Rotation and this will create a centrifugal force and this will affect the results. (3.) The moon is one of the biggest force around Earth and this will have a huge effect on the calculations General limitations: (1.) The space is twisted by gravity and this will change the distance between each object (2.) The space is expanding and even though the solar system will not expand, but this will affect the distance change in stars and galaxy. (3.) The path of the light will change because of the twist of the space and this might affect the results.
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