Trigonometric Parallax may seem like an unfamiliar and complicated topic, but people use it millions of times a day without even realizing it. The definition of Parallax as of Dictionary.
com is “The apparent displacement of an observed object due to a change in the position of the observer”. Whenever somebody looks at an object, their two eyes see it at slightly different angles. If you were to hold your finger out in front of your eyes and open and close your left and right eyes, you will see your finger slightly moves. This causes it to adjust, which is a simple form of parallax. When humans do this, it is called stereo vision. This occurs when your eyes see an object relative to something in the background. This is called depth perception.
This is all related to parallax.The only difference between Trigonometric Parallax and Stellar Parallax, is that it is used in space. More specifically, used to measure the distance of stars within our galaxy. This is dependant on a large relatively stationary star in the distance.
An example of this is when you are driving on a road. If you drive towards a tree with a mountain in the background, the tree will move but the mountain will not. This is exactly what they do in space, but rather a star and not a mountain.
Parallax is “The best way to get distance in astronomy,” said Mark Reid, an astronomer at the Harvard Smithsonian Center Of Astrophysics. In space calculations, observers begin with calculating the distance of a star in one location on Earth. Then after six months, they observe the distance again, because by then, the Earth has rotated 180 degrees. This gives them another reference point to compare their previous calculations. As you recall from earlier in the paper, this is similar to the closing of the left or right eye. You get different perceptions on distance. Although this concept seems rather simple, it requires difficult trigonometric calculations. When dealing with parallax calculations, it requires some unusual unit measurements some people are not use to.
The basic equation for parallax is D=1P. In the case, D is actual distance measured in something called parsecs. This is defined as something that contains a parallax of one arcsecond.
This comes out to about 3.26 light years. The next part of the equation is 1P. P in this case, is just the parallax angle observed. The more distant an object is, the smaller its parallax. As an example I am going to use the star “Vega”. This star has a parallax of 0.
129 degrees. So, D=10.129. This comes out to D=7.75pc. Multiply this by the number of light years in each parsec and you end up with the star “Vega” being about 25 light years away. This star had a relatively small parallax angle measure of 0.
129 degrees. The only star seen from Earth that has a parallax measurement greater than 1 is the sun. Now that I have gone over the structure of what Trigonometric Parallax is, I will begin to cover the history and origins of where it all began.The first known measure using parallax occured in 189 B.C. This was made by Greek astronomer, Hipparchus. He was famous for observing a solar eclipse from 2 locations to measure the distance of the moon. However, in his study, he observed the moon to be 350,000 miles away.
This is 50% further than our measurements today. This is so because with his lack of resources, he assumed the moon was directly overhead which caused a miscalculation in the angle difference of his two measuring locations. Although Hipparchus’ measurements were incorrect, it opened a brand new door for other astronomers and their calculations. His ideas are not only being used today, but are the number one method for star distance calculations in the world. In addition to these early calculations, it caused other astronomers to attempt to perfect his equation also. Hundreds of years passed before the first parallactic measurement was made in 1838. This was made by a man named F.W.
Bessel. He measured the distance of a nearby star, Cygni. He concluded that the star was at a distance of 3.57 parsecs away.
With more recent calculations, Cygni is now known to be 3.48 parsecs away. Ever since then, scientists have spent time perfecting their equations leading to the most exact solutions possible. As time goes on, their calculations become more and more exact, while using the same principles created hundreds of years ago. In the science world, Trigonometric Parallax falls in a sector called “The Distance Ladder”. The Distance Ladder is a series of different ways astronomers measure distances in space.
Sitting on top as the most key method of the ladder is Trigonometric Parallax. Without Parallax, you are unable to use any other measurements. It is essentially the Sun of space measurement, seeing how everything revolves around it. As you go further up the Distance Ladder, measurements get less accurate. This is why Trigonometric Parallax is the most frequently used method for scientists worldwide. As you can see, Trigonometric Stellar Parallax is a very commonly used method, but is something that is not very well known to the average person. It deals with what looks like a fairly similar equation, but can get very complicated with its units and measurements.
This method has been around in the science world for a long time and is becoming more and more precise every day. For something that we humans use every day without knowing it, it’s amazing how crucial it can be in space astronomy. Trigonometric Stellar Parallax is the number one used space measurement of distance in the world and is also the most exact. With all of its purposes in Space and Earth, it is one of the greatest unknown methods of science in history.