# The Distance from the Earth to the Sun in kilometers and in light years.

Every day you can see the Sun from anywhere on Planet Earth. The star king illuminates the planet with such intensity that it gives the sensation that it is close. But nothing is further from reality, since the solar star is millions of kilometers away.

Do you know what is exactly the distance from the Earth to the Sun?

### The astronomical unit

1. The distance from the Earth to the Sun is millions of kilometers.

The distances in space are enormous and it is difficult to give them a number with the units that we use on a daily basis on Earth, such as meters or kilometers, the space between stars is millions or trillions of kilometers, and between galaxies even much larger so we have to look for units that simplify the numbers and we are not cumbersome to use them. In the case of the solar system we use the astronomical unit (ua), which is the average distance from the earth to the Sun, but for places far away from the solar system we use the light year. .

Throughout history, astronomers have tried to find the exact distance between the two celestial bodies and establish a unit of measurement for it. It was in 2012 when the International Astronomical Union decided to adopt an exact measurement and thus created the astronomical unit that accurately measures the distance between the Sun and planet Earth and is exactly equivalent to 149,597,870,700 meters. In this way, scientists can quantify distances in space using this unit and facilitating their work.

The distance between the two celestial bodies has been measured using modern technology that made it possible to do it precisely. Thus, they have established a unit that determined the average distance, since the Earth, when orbiting the Sun following the Kepler model with an elliptical trajectory, there are times when it is more or less distant from the Sun. Around January 4, the Earth is as close as possible: about 147 million kilometers away from the Sun. On the other hand, it is around July 4 the moment of greatest distance, when it increases to 152 million kilometers.

The elliptical shape of the orbit means that it is not a perfect circle, but rather a kind of stretched circle in which the Sun is not exactly in the center.

Until the second half of the 20th century, parallax measurement was the only reliable way to calculate distances in our Solar System. Later the definition of the astronomical unit incorporated the Gaussian gravitational constant, which complicated the calculations and caused problems for astronomers. Despite the complicated calculations, the distance value was quite approximate. The new value is based on direct observation, since modern techniques allow direct measurement of distances with precision

2. In light years, What Is The Distance from the Earth to the Sun?

For distances in the solar system we can also use, apart from the astronomical unit, the second light, light minutes or light hours .

For even farther distances, especially for very distant stars and galaxies, the Parsec , which is equivalent to 3.26 light years, is used, and for much farther distances, the kiloparsec or the megaparsec

Since the speed of light is 299,792 km / s, and a year has 31536000 seconds ( the Julian year is considered: 365.25 days ), Earth is located 0.000015 light years from the Sun, which is equivalent to about 8 light-minutes . This means that if we could travel at the speed of light (300,000 km per second), it would take that amount of time to reach the Sun from our planet. If we want to express it in terrestrial measurements, the Earth is about 150,000,000 km from the Sun.

What is a light year?

Surely you have encountered many times with the measure of “light-year” in a documentary or book on astronomy. On our planet, measuring a distance in kilometers or thousands of kilometers is practical and gives us a good idea of how far one point is from another. However, in space the distances are infinitely greater, so logically using the kilometer measurement will be small. That is why the “light-year” is used as a unit of distance, which makes it easier to imagine how far some stars or galaxies are from us.

As its name implies, a light year is equal to the distance light travels in 1 year (365 days). Since light travels at about 300,000 km / s, you can see that it is a huge unit, to the point that we have already seen that the Sun is “only” 8 light-minutes away. But when it comes to measuring distances between stars or galaxies, even this light-year measurement becomes insignificant many times. If you want to spend it in kilometers, 1 light year is equivalent to 9.46 Ã— 10 12 km (9,460,730,472,580 km).

Now, in the scientific and specialized world, the parsec unit, which is equivalent to 3.26 light years, is more used. For the rest of the mortals, the measure of the light-year is enough … If you want to know what would be achieved (or almost) in a light-year, we can tell you that we could touch the nebulae Cat’s Eye with your fingers, Stingray and the Barnard 68 molecular cloud, as seen in the following figure.

Interesting astronomical data

â€¢ Based on the theory of relativity, no object with a mass greater than 0 g can accelerate to the speed of light, since the closer you get to this speed, the heavier it will get.

â€¢ The distance between the Sun and the closest star to us (Proxima Centauri) is 4.22 light years.

â€¢ The diameter of our galaxy, the Milky Way, is 150,000 light years.

â€¢ The distance between our galaxy and the closest galaxy to us (Can Mayor) is 25,000 light years.

â€¢ Our galaxy is located next to an agglomeration of other galaxies in space, called the Local Group. If we measure the diameter of it, we will reach 10,000,000 light years.

â€¢ ALL of the universe that can be observed from planet Earth is estimated to measure 13,700,000,000 light years.

â€¢ The farthest planet in the Solar System is Neptune, and is located at a distance of 0.0006225945297850989 light years. In other words, if we traveled at the speed of light from Neptune to the Sun, it would take 4.16 hours.