The distance between the sun and the earth, also known as the distance between the sun and the earth, refers to the distance between the sun and the earthGeocentricLine length of.Because the earth moves around the suntrackIt is an ellipse. The sun is at a focus, so this distance is changing all the time. Its length is about 149597870 kilometers.The sun earth distance is also a length unit in astronomy. It was once defined as the average distance between the earth and the sun, but has now been changed to its absolute distance of 149597870700 meters. Astronomically, this length is determined as 1AU, that is, an astronomical unit.
The Earth Sun Distance is aAstronomical unitThe maximum value is 152.1 million kilometers (the earth is at the apohelion), the minimum value is 147.1 million kilometers (the earth is at the perihelion), and the average value is 149.6 million kilometers. According to this distance, it only takes 8 minutes and 18 seconds for sunlight to reach the earth's surface.
measuring method
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The distance between the sun and the earth can be measured by using the transit of Venus (that is, the sun, Venus and the earth are just in a straight line) and asteroids. Historically, the distance between the earth and the sun was measured using the previous method.
Measurement history
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In 1716, Haley proposed the method of measuring the distance between the sun and the earth by observing the golden transit at different places[1]。
In 1672, Giovanni Cassini, astronomer and engineerbecomeThe first person in history to accurately measure the distance between the sun and the earth.Cassini compared the distance to Mars measured by himself with the observation data of his colleague Jean Richer, and combined their calculations, he found that the distance from the sun to the earth was about 87 million miles, which was quite close to the data assumed by 1976 astronomers.
In 1677, 21 year oldHarleyHe predicted the Venus transit in 1761, and he knew that he could not see it in person.But Halley believes that as long as the apparent diameter of Venus is obtained by observing the transit of Venus and the revolution period of Venus is known, thenSolar parallaxIt can be easilyKepler's third lawCalculate the distance between the sun and the earth.
In 1761, as expected by Halley, there was a transit of Venus. However, because the path of Venus was too close to the edge of the sun to be measured accurately, astronomers had to meet eight years later to complete Halley's ambition at another transit of Venus in 1769.
On May 23, 1769, the astronomer in EuropeTahitiWith the cooperation of Captain Cook, we finally got accurate observation data.It is worth mentioning that Britain and France were at war at that time, but in order to complete this historic scientific exploration mission, the French government specially ordered the navy not only not to attack Captain Cook's Endeavour, but also to protect its navigation safety.It is under this kind of international cooperation that the "astronomical unit" that has not been solved for hundreds of years can be seen in the world under this rare astronomical opportunity.
In 1771, French astronomer Lalande calculated for the first time that the distance between the earth and the sun was about 152 to 154 million kilometers based on this precious observation data, which was very close to the 1976 measurement value of 14959787069.1 million kilometers.
