**Introduction**

In this experiment(How Accurate is Parallax),, we will be determining the accuracy of the parallax equation in measuring the distance between star and earth. We will take stars as dependent variables and distance as an independent variable for performing this experiment.

We hypothesised that as the distance increases, accuracy decreases.

**Aim**

To determine the accuracy of parallax in measuring the distance between the stars and the earth.

**Theory **

- The apparent difference in the position of an object on viewing from two different lines of sight is called parallax.

2. The method that uses two apparent points to measure the distance from the observer is called the parallax equation. The distance measure to star = 1/ parallax angle. **d = 1/p.**

**Materials Required**

1. Candles

2. Balls

3. A pole

4. Notebook

**Procedure**

**Step 1.** For representing stars, use candles. And for representing the earth and the sun, use balls.

**Step 2.** Place four candles (four stars) each at a distance of 0.9398, 2.921, 4.9276, and 5.5372 from the ball (the earth).

**Step 3.** To show the relative stars, use a pole.

**Step 4.** Place the earth in the position of January. And obtain the degree of angle for each of the four stars.

**Step 5.** Place the earth in the position of July. And obtain the degree of angle for each of the four stars.

**Step 6**. Use the baseline as 1.8288 meters.

**Step 7. **Calculate the value by using the parallax equation.

**Step 8.** Record your observations.

**Observation**

1. We calculated all the values in inches but later converted them to meters.

2. We placed our first star 0.9398 meters away from the earth. But by measuring with a parallax equation, it came out to be 0.87122 meters.

3. The star that we placed at a distance of 2.921 came out to be 3.302 meters on calculating with the parallax equation.

4. The star that we placed at a distance of 4.9276 meters from the earth came out to be 4.28752 meters with the parallax equation.

5. And, the last star that we placed at a distance of 5.5372 meters from the earth came out to be 3.556 meters with the parallax equation.

**Result**

1. Our hypothesis, which suggested that on increasing the distance, the accuracy of the parallax equation decreases, was right.

2. Our first measurement was almost similar (of 0.6858 difference) with the parallax value.

3. The farthest star has the largest difference of 1.9812 between the parallax measurement and our measurement.

**Precautions**

1. Put all the values correctly in the parallax equation.

2. Record your observation precisely.

**Conclusion**

In this experiment, we determined the accuracy of the parallax equation in measuring the distance between earth and star.

** Viva Questions with Answers**

**1. What was the aim of your experiment?**

ANS. We aimed to check the accuracy of the parallax equation.

**Q.2 What is the formula for the parallax equation?**

ANS. The distance to a star, d = 1/p. Where p is the parallax angle and measured in arc-second and d in parsec.

**Q.3 What was the result of your experiment?**

ANS. We saw that on increasing the distance, the accuracy of the parallax equation decreases.

An Indian nuclear physicist, founding director, and professor of physics at the Tata Institute of Fundamental Research.

## 0 Comments