The distance between the Sun and the Earth has been tried many times throughout human history. However, measurements often produced different results. The methods and calculations used have always changed. We explain the adventure of the changing world of science measuring the distance between the Sun and the Earth.
The sun is at the heart of our system. All objects in the Solar System – planets, asteroids, comets, etc. – revolves around the Sun at different distances. Mercury, the closest planet to the Sun, is 47 million kilometers away from the Sun in its orbit. The objects in the Oort Cloud, the shell of the solar system, can be about 15 trillion kilometers away from the Sun. What is the distance between the Sun and Earth?
The Earth is 100,000 times closer to the Sun’s distance to the Oort Cloud, which is an average of 149,597,870 km. This distance is called “astronomical unit (AU), which is used to measure distances in the Solar System:
1 AU = 149 million 597 thousand 870 kilometers
According to this unit, Jupiter is 5.2 AU away from the Sun. Neptune is 30.07 AU away from the Sun. According to NASA, the distance to the nearest star, Proxima Centauri, is calculated as 268 thousand 770 AU. However, to measure longer distances, astronomers use light-years or the distance that light travels in a year. So Proxima Centauri is located about 4.25 light-years away.
1 light-year = 63,239 AU
The ever-changing distances between the Earth orbit and the Sun:
AU is the average distance between the Earth and the Sun. The Earth revolves around the Sun every 365.25 days. But the Earth’s orbit is not a perfect circle, but rather an oval or elliptical shape. For a year, the Earth is sometimes closer to the sun, sometimes farther away.
The Earth’s closest approach to the Sun, called the “perihelion, takes place at the beginning of January and approaches about 146 million kilometers. The point where the Earth is most distant from the Sun is called an aphelion) and takes place in early July. At this point, the world is more than 1 AU, about 152 million kilometers away.
- Dumpling distance: 146 million kilometers
- Distance to sun: 152 million kilometers
Attempts to find the distance between the Earth and the Sun:
According to the written history, the first person to measure the distance to the Sun is the Greek astronomer Aristarchus of Samos. Measurement of BC. It has been around 250 years. He used the phases of the moon to measure the dimensions and distances of the Sun and the Moon.
He assumed that the Sun would be 19 times farther than the Moon by measuring the angles of extension of the Moon, so it would be 19 times larger. But in fact, the Sun is 400 times larger than the Moon. Aristarchus’ error was that he did not consider breaking the Earth’s atmosphere.
Aristarchus, however, provided a basis for understanding the size and distance of objects through his observations. This foundation, though not certain in time, made him think that the Earth revolves around the Sun. This idea emerged 1700 years ago before the Sun-centered system theory presented by Nikolas Copernicus.
In 1653, astronomer Christiaan Huygens calculated the distance from the Earth to the sun. He used the phases of Venus to find angles in the Venus-Earth-sun triangle. For example, when Venus appeared half-illuminated by the Sun, the three bodies formed a right triangle from the Earth’s point of view.
By accurately predicting the size of Venus, he was able to determine the distance from Venus to Earth. As a result, he was able to measure the distance to the Sun from the angles of the triangle. However, you cannot hear much of Huygens’ name because his method is partly based on prediction and is not entirely scientifically based.
In 1672, Giovanni Cassini used a parallax method to find the distance to Mars, and he also found the distance to the sun. While in Paris, he sent his colleague Jean Richer to French Guiana. They calculated the location of Mars by looking at the stars in the background.
They then combined this calculation with the known distance between Paris and French Guiana to form a triangle. Thus, with the discovery of the distance to Mars, the distance to the Sun could be found. Since this method is more scientific, we hear this brother’s name more.
Everything is okay … How do we measure the distance between us and a place we can’t go?
With the emergence of spacecraft and radars, more accurate methods for measuring the distance between the Earth and the Sun have emerged. Therefore, with the new observations, it is concluded that the Sun gradually lost its mass and the orbital circulation time of the Earth increased.
This means that the astronomical unit gradually shrinks (about 1 cm per year). Due to the uncertainty in the Gaussian constant found in the old definition of the astronomical unit, the mass of the Sun is not fully known.
Therefore, the International Astronomical Union voted in August 2012 to make the definition of the astronomical unit a flat number, and the number was 149,597,870,700 meters. The measurement is no longer related to the mass of the Sun and is based on the speed of light, whose value never changes. Scientists also agree that the new definition is more understandable than before.