While some astronomers are dedicated to monitoring the Moon from the largest observatories in the world, others are constantly shooting laser beams towards the natural satellite. The most surprising thing is that this is not a new method, but rather scientists have been sending signals to the Moon for more than half a century. What is the reason? Know the distance from the Earth to the Moon.
How do you know the distance from the Moon to the Earth?
Humans have questioned the distance from the Earth to the Moon since ancient times, but the first to accurately calculate this length was
Thanks to Hipparchus’ detailed observations and his advanced use of trigonometry, he was able to calculate the distance from the Earth to the Moon for the first time. Its result was 348 thousand kilometers and although its calculation has a margin of error of 36 thousand kilometers, this was the first time that humanity knew the distance between the planet and its satellite.
Since then the distance calculation has been going around among astronomers, but we did not find an exact figure until man found a surprising method of calculating the separation between the two bodies.
What is the distance between the Earth and the Moon?
Today we know that the average distance of the Moon is 384 thousand 400 kilometers, but you should keep in mind that it is an average figure because our Moon does not have a completely round orbit and there are times when it is closer or further away from us. To know how astronomers know these data precisely, we must go back half a century, to the famous Apollo 11 commanded by
The Apollo missions were responsible for putting man on the Moon for the first time and although it has been widely questioned whether the event was true, precisely one of those ways to demonstrate the veracity of trips to the Moon is that thanks to them we know the exact distance between the Earth and its satellite.
The crew of the Apollo 11, 14 and 15 between 1969 and 1971 were responsible for bringing the so-called Laser Ranging Retro-Reflector to the lunar surface., a kind of reflectors. The astronauts toured the terrain of the Moon to leave the laser range photoreflectors, which are made up of hundreds of mirrors capable of reflecting light in any direction it comes from. Additionally, the robotic rovers called Lunokhog 1 and 2 also have reflectors in their composition. Altogether there are five reflectors on the surface of the Moon distributed as you can see in the image above and which continue to operate today.
Half a century shooting lasers at the Moon
We know that the speed of light is 300 thousand kilometers per second and with this fact, the basis behind the experimentation of mirrors on the Moon, is simple: point a beam of light at the reflector and time the amount of time it takes. It takes light to return to the starting point. This allows you to obtain accurate data with millimeters of error range.
This is why astronomers They have been sending laser pulses towards the Moon for five decades, to obtain the exact distance between the Moon and Earth.
Although the process is not at all simple, the Moon travels at 5,700 kilometers per hour and the efficiency of the reflectors is decreasing. It is believed that lunar dust has been clouding the light-reflecting ability of the five reflectors and for this reason, they are becoming less accurate. But there is another factor: the Moon is moving further and further away from the Earth, a fact that we also know thanks to the system of mirrors on the surface of the satellite.
The Moon moves away at a rate of 3.8 centimeters each year. It may not seem like much, it is even about the same speed at which our nails grow, but it is still an important factor that could also be influencing the efficiency of reflectors is decreasing more and more.
Without a doubt, science is amazing, a basic experiment taken to stratospheric scales has helped us learn more about our natural satellite and how it behaves.