How do we know how far the sun and other planets are from the Earth?

The planets' average distances from the Sun, expressed in millions of kilometers, are as follows: Earth - Mercury: 91.7, Earth - Venus: 41.4, Earth - Mars: 78.3, Earth - Jupiter: 629, Earth - Saturn: 1283.9, Earth - Uranus: 2722.9, and Earth - Neptune: 4345.5. Although there are mini/max variations, the average distances of the Earth from the other planets are the same as the differences of average distances from the Sun, as stated below.

Through a variety of techniques, such as triangulation in geometry, radar ranging, and astronomical observations like parallax, Kepler's laws of planetary motion, and the timing of transits or occultations, we are able to determine the distances to the Sun and other planets from Earth.

The distances between the Sun, planets, and Earth are determined through various methods, including geometric calculations, astronomical observations, and spacecraft missions. One method involves using triangulation with the Earth's orbit as one side of the triangle to calculate the distance to planets based on their apparent positions in the sky at different times of the year. Another method, called radar ranging, involves bouncing radio waves off planets and measuring the time it takes for the waves to return to Earth, allowing scientists to calculate distances accurately. Additionally, spacecraft missions, such as those conducted by NASA and other space agencies, provide direct measurements of distances using onboard instruments and sensors. These methods collectively contribute to our understanding of the distances between celestial bodies in our solar system.