In the literature we find that, to calculate the distance in parsecs (pc) to a particular star, we need to know the parallax angle in seconds of an arc, and determine the reciprocal of it. The question I would like to explore in this lesson is, the why do we do this. Look at theContinue reading “Lesson 5”

# Category Archives: LECTURE

## Lesson 4

In Lesson 1 you can follow the definition of the Astronomical Unit based on a “test” particle, that takes to revolve around a major body, exactly one year. We saw, that based on this definition, the Earth’s distance from the Sun is slightly smaller, compare with the test particle’s distance around the Sun. The resultContinue reading “Lesson 4”

## Lesson 3

This lecture can be used as for college level students. To continue with the understanding of Kepler’s laws, the presentation is a build up of the Physical-Mathematical concepts of the 2-Body problem and reduced mass. It culminated with the deduction of the total energy for the reduced mass system. The results will be used inContinue reading “Lesson 3”

## Lesson for Today- Lesson 02

How do Planets, or other objects move around a star? The observations of the German astronomer, Johannes Kepler (27 December 1571 – 15 November 1630), deduced the three laws that are being used today to answer that question. I will describe the three laws in three different lessons, starting today with the first one below.Continue reading “Lesson for Today- Lesson 02”

## Lesson for Today – Lesson 01

The Astronomical Unit – Definition The distance from a particle (or a planet) to the Sun, is measured in terms of the semimajor axis of the ellipse traced by that body around the Sun. According to Kepler’ law, the square of the period (time that the body takes to go once around de Sun inContinue reading “Lesson for Today – Lesson 01”