“What are Kepler’s Laws? Explained by Johannes Kepler”

CNN Indonesia

Wednesday, 10 May 2023 09:00 WIB

Jakarta, CNNIndonesia —

Kepler’s laws describe the orbital motion of each planet which revolves around the sun as the center of the system. What are the contents of Kepler’s Laws found?

There are three Kepler laws, namely Kepler’s First Law, Kepler’s Second Law, and Kepler’s Third Law, which explain how planets orbit sun. This law changed the ancient view that the earth was the center of the solar system.

The three astronomers who changed the ancient view of the sun, moon, planets and stars revolving around the earth were Copernicus, Brahe and Kepler.

Kepler’s Law discoverer

The discovery of Kepler’s Laws cannot be separated from the role of Johannes Kepler, a scientist from Germany who became Brahe’s assistant at the age of 29, as quoted from Class X Physics eModule by Herry Setyawan.

Kepler studied observational data collected by Brahe over 30 years. The data convinced Kepler that geometry and mathematics could be used to describe numbers, distances, and planetary motions.

According to Kepler, the sun is the center of the system or heliocentric. From his analysis of Brahe data, Kepler discovered the laws that explain the orbital motion of each planet around the sun.

What Are Kepler’s Laws?

What are the contents of Kepler’s laws that have been compiled? Here’s an explanation.

Kepler’s First Law

Kepler’s First Law reads, “All the planets move in ellipses around the Sun with the Sun at one focus of the ellipse.”

This law describes the shape of a planet’s orbit, which is described as an ellipse, not a circle. Most of the planets follow low eccentricity orbits. When viewed from the orbit of the planet, it is not clear whether the orbit is an ellipse.

But from the evidence of Kepler’s calculations, the orbit is an ellipse which allows objects in space far from the sun to have elliptical orbits and the sun is at one of its focuses.

Kepler’s Second Law

Kepler’s Second Law states “An imaginary line joining the Sun and a planet sweeps out equal areas of the arc in equal time intervals.”

From its sound, the law explains the matter of the orbital speed of a planet.

If the planet’s orbit is equal to t1=t2=t3, then the area that sweeps the wedge at the same time has the same area (A), namely A1=A2=A3.

Kepler’s III law

Kepler’s Third Law reads: “The ratio of the square of the period to the cube of the half axis of the ellipse is the same for all planets.”

This law is related to the period of revolution of each planet around the sun.

Kepler’s III law was discovered in 1619, 10 years after Kepler’s first and second laws were published. At that time Kepler was looking for relationships between the motions of different planets and explanations for calculating those planetary motions.

Thus a review of the contents of Kepler’s Laws that you can learn. Hope it is useful!

(glo/soup)