# What was Ptolemy contribution to astronomy?

## What was Ptolemy contribution to astronomy?

Ptolemy made contributions to astronomy, mathematics, geography, musical theory, and optics. He compiled a star catalog and the earliest surviving table of a trigonometric function and established mathematically that an object and its mirror image must make equal angles to a mirror.

## How did Aristarchus change the world?

Aristarchus was one of the first astronomers to calculate the relative sizes of the Sun, the Moon and the Earth. He did this by observing the Moon during a lunar eclipse and by estimating the angle and the size of the Earth.

## How were Kepler’s laws proven?

Kepler’s Laws of Planetary Motion Brahe had collected a lifetime of astronomical observations, which, on his death, passed into Kepler’s hands. In an attempt to prove his theory, Brahe compiled extensive astronomical records, which Kepler eventually used to prove heliocentrism and to calculate the orbital laws.

## What is the Earth’s eccentricity?

Earth’s orbital eccentricity e quantifies the deviation of Earth’s orbital path from the shape of a circle. It is the only orbital parameter that controls the total amount of solar radiation received by Earth, averaged over the course of 1 year. The present eccentricity of Earth is e ≈ 0.01671.

## Does the Earth’s angle change?

Today, the Earth’s axis is tilted 23.5 degrees from the plane of its orbit around the sun. But this tilt changes. During a cycle that averages about 40,000 years, the tilt of the axis varies between 22.1 and 24.5 degrees.

## What is the eccentricity of Mars?

Orbital parameters

Mars Earth
Orbit eccentricity 0.0935 0.0167
Sidereal rotation period (hrs) 24.6229 23.9345
Length of day (hrs) 24.6597 24.0000
Obliquity to orbit (deg) 25.19 23.44

perihelion

## What is Earth’s period?

365.25636 solar days

around 24 hours