Astronomical unit

The astronomical unit is the distance between the sun and the earth. It is also used as a unit to measure distances in the solar system. The average distance between the sun and the Earth is 149.6 million kilometers or 92.96 million miles. The distance between the sun and the earth is an estimate because the Earth's orbit around the sun is elliptical. The distance between the sun and the earth At the beginning of January, the astronomical unit is used to estimate the distance between the sun and the planets when the size of the planet is small in relation to the size of the solar planet, in addition to not adjusting the distance between them throughout the year.
The Greek astronomer Aristarchus was the first to try to estimate the distance between the sun and the earth at 250 a. C., then Christian Huygens tried to estimate the distance between the sun and the earth in 1653, while making his estimates through Venus, which helped him get to the idea that when half of Venus is illuminated in the light from the sun, a triangle with three heads is formed: the sun, Venus and the Earth. You are not a lawyer of scientific evidence, so you are not very specific.

The researcher Giovanni Cassini conducted an investigation in 1672 based on the principle of angular difference or different vision with a different angle of vision (in English: Parallax), which forms a celestial triangle from Earth, the Sun and another third planet, where determined the angle of light of the third planet on Earth, which allowed Giovanni Find the distance between Mars and Earth, then discover the distance between the Sun and Earth. chemistry analysis
In 1976, the International Astronomical Union (IAU) defined astronomical unity as the distance between the Sun and infinite particles, which orbits in a circular orbit for a year. This definition depends on the mass of the Sun, which is constantly decreasing and, therefore, the astronomical unit changes continuously and does not remain constant.

Several modern and direct methods have been found to measure the distance between the sun and the earth, using advanced technology, radar, and advanced spacecraft. In August 2012, the distance between the Earth and the Sun was 149,597,870,700 km.