6. Circles, circumferences and planets 🪐

Let's delve into the universe of circular geometric figures!

Although many people confuse them, circles, and therefore circumferences, are not polygons, as they have no vertices, angles or straight lines.

We can say that a circle is a plane geometric figure that is defined as the set of all the points that are at a fixed distance from the centre, while the circumference is the curved line that results from drawing a line around the perimeter of the circle.

In the astronomical world, it is not very difficult to find these figures.

• Circular orbits.

The planets orbit the Sun in circular paths, which means that their orbits resemble perfect circles. This property is based on Isaac Newton's Law of Universal Gravitation, which states that the force of gravitational attraction between two bodies is inversely proportional to the square of the distance between them. (Earth Orbits, n.d.)

• Motion in cycles

Planets can also be related to circles through the concept of cyclic motion. The planets move in cycles that repeat at regular intervals, such as seasons or leap years. These cycles can be represented as a circle that is completed after a specified period of time (El Movimiento De Los Planetas En La Antigüedad, n.d.).

• Planetary Geometry

Geometry is also used to describe the relative positions of the planets. For example, the relative positions of the planets in the solar system can be represented using geometric patterns, such as the regular pentagon of the planets visible to the naked eye (Mercury, Venus, Mars, Jupiter and Saturn) or the elliptical orbits of the outer planets (Geometría Planetaria, n.d.).




In short, the planets are related to circles and circles through their circular orbital motion, their cycles of motion and the geometry that describes their relative positions in the solar system.

Possible class project: "Design your own planetary model".

Aim: Students will design and create a model of the planets using circles and circles.

Materials:

• Paper
• Coloured pencils or markers
• Compass
• Scissors
• Glue
• Cardboard or some sturdy material for the background

Steps:

1. Introduction: Begin by introducing students to the concepts of circles and circles, and explain how they relate to the planets and their orbits. Briefly discuss how geometry can be used to represent space and celestial bodies. 
2. Selection of planets: Ask students to select at least five planets from the solar system to include in their model. Students can choose planets that interest them or use the five planets visible to the naked eye: Mercury, Venus, Mars, Jupiter and Saturn. 
3. Drawing the planets: With the help of a compass, students will draw circles and circles to represent the planets and their orbits around the sun. Students can use different colours for the planets and orbits, and can label each with the name of the corresponding planet. 
4. Cut out and glue: Students will cut out their circles and circles and glue them onto construction paper or some other sturdy material to make the background. Students can place each planet in its corresponding orbit around the sun.
5. Presentation: Ask students to present their planetary models to the class. Each student should explain how geometry was used to design and create their model, and what planets and orbits they included.

This activity fosters understanding of the concepts of circles and circles and how they apply to planets and their orbits. It is also a fun and creative way to learn about the solar system and its planets.