# 1G

## Part 1G: Classify an Asteroid’s Orbit

Two of the orbital elements found in the previous part, the semi-major axis, a, and the eccentricity, e, can be used in a simple calculation to provide a broad classification of an asteroid’s orbit. We will use the following three classes. You may want to look up their formal definitions.

##### Main Belt Asteroids

Let’s write a script in Quorum, using what we have learned so far, to calculate the orbital class of an asteroid.

First, a discussion of some concepts:

1. The calculation uses the unit “au”, which is the abreviation for astronomical unit.

• An Astronomical Unit (au) is the average distance of about 93 million miles (or 150 million kilometers), between the Earth and the Sun. Astronomical units (au) are most often used to measure distances within our Solar System

2. The six orbital elements, which includes the semi-major axis (a) and eccentricity (e) of an asteroid, are found after the data from a number of observations has been entered into a special software program that calculates orbits.

• The program starts with 100 possible orbits.
• The number of possibilities is reduced as the data from more observations are entered.
• Once an orbit is finalized, the elements, like “a” and “e”, are calculated by the software and can be used to find its classification.

3. The obital classification depends on the asteroids closest and farthest distance from the sun. These distances are called perihelion and aphelion.

• Use your journal to write the formal definitions of perihelion and aphelion (look them up).
###### Now we are ready to write the coding script:

4. The calculation needed to classify an asteroid’s orbit involves finding the perihelion and aphelion of an asteroid using the semi-major axis(a) and the eccentricity(e). Use the following data for this sample asteroid:

###### a=1.458, and e=0.2226. Correct classification: NEA (Near Earth Asteroid)

5. Open a Quorum Box

The following are some guidelines for writing the script:

• a.) Start the program with input statements that ask for the asteroid’s name and the data needed.
• b.) Select the correct variable types to “cast” the input data into.
• c.) Use consistent variable names. Usually, “q” stands for perihelion, and “ap” stands for aphelion
• d.) Use the following equations to calculate “q” and “ap”:
• ##### ii.) ap = a(1+e)
• These equations will provide numbers in Astronomical Units.

e.) Next, use the conditional statements you learned previously, “if” and/or “elseif”, with the following criteria:

##### if q > 1.4 = Main Belt

f.) Don’t forget to end with a user-friendly output or say statement

Work with a partner or two to write this coding script which classifies an asteroid’s orbit.

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Teachers/leaders see this example script if you need help.

Possible Scripts
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#### ACTIVITY: Classify These Asteroids:

Use the coding script you developed above and the Quorum Box you have your successful code in to calculate the orbital classification of the five asteroids listed below. You will need to look up the aphelion and perihelion of each. Wikipedia has the information readily available. Record your findings in your journal.