[Physics Class Notes] on Measurement of Length – Triangulation and Parallax Method Pdf for Exam

Measurement of the length of any object can be done in different methods. Measuring length is a regular need for many offices. We can measure the length of your book, table, furniture, even distance between places cannot so be measured as length. But Different ways are used for different objects. Similarly to measure the distance between one star to another star or one object to another object in the space, the available methods are triangulation and parallax method. 

These methods are widely used by Astronomers. So, let’s start learning about measuring distance by triangulation and parallax methods in detail. Before going to learn about the parallax method, let’s have a glance at the triangulation method with an example.

Measuring Distance by Triangulation

The parallax method uses the triangle to describe the distance or length between Stars. Let’s discuss how it will be.

The triangulation method refers to the process of finding the values of three elements required to form a triangle and is used to find the distance or location of an object in space. Along with astronomers, their triangulation method is also used by surveyors and architects. When the distance or location of your point is unknown, they use this triangulation method to find out that point of location by using the other two points.

Triangulation Example

The triangulation example helps to get a clear idea about measuring distance by triangulation. Let’s find the distance of a ship from the shore using the triangulation method. 

Steps involving Measurement of Length using the Triangulation Method 

• Let us consider two linear points on the shore as a baseline AB.

• Also consider the angles extended by A and b to the ship as α, β respectively. These are the angles from seashore to ship.

• no, we have the length of baseline, two angles at 2 points. By substituting all these values, we can find the direct distance from the ship to the seashore.

Parallax Method

Using the principle of triangulation method, the distance measurement by parallax method will be done. Several astronomers benefited from the Parallax method. The Parallax metal refers to the apparent change in position of the object in space when viewed from two different points of position. That’s the reason, the parallax method takes half of both angles at both points. This forms a triangle and leads to the usage of the triangulation method. 

Illustration

For instance, if we observe from a vehicle, the other closer objects move faster and the farther objects move slower. This difference happened because of observation. Hence, the parallax method is the best way to measure the distance between Stars. It was recommended by several astronomers. Especially Mark Reid, an astronomer at the Harvard Smithsonian Center for Astrophysics, quoted that the Parallax method is a golden standard for the measurement of length.

Distance Measurement by the Parallax Method

The measurement of length can easily be determined by using the triangulation and parallax method. That means, using and applying the principle of triangulation method in the parallax method to measure the distance between two stars. 

Let’s consider one distance to the star and a near start from the Parallax motion. So, using The Parallax method, we need to take half of two angles formed by these two points. From those two angles, we can easily find the third value by using the triangulation method of measuring distance. One point is specifying the far distance from the earth to the star and the other point is specifying the near distance from here to the star.

Now, we have the values of parallax angle, distance from the earth can be considered as radius. The distance can be detected by using The Parallax method whether it is far or very small. Every minimum distance of your star can be identified by using The Parallax method accurately. That’s the reason, several scholars have praised this method and achieved success by implementing this.

The measurement of length which is the distance between Stars can be measured using the unit parsecs. If we take p as a parallax angle which is measured in arcsecs, then the distance will be reciprocal to the parallax angle. It can be represented as, 

D(parsec)=1/p(arcsec)

d = 1/p

Hence the distance can be measured by triangulation and Parallax methods.