True, the light we see from it is coming from the Sun.

But the measurement you get from shining a laser into these retroreflectors is orders of magnitude larger than what you would get if there were no retroreflectors and point at the moon. You can literally do that now, you get a very low reading while pointing at another surface on the moon and the moment you get to the retroreflector it spikes.

Ribbit

Some have been put there by astronauts, others by robots

So the astronauts had to put those mirrors down on the surface or could it be mounted on top of a rover? 

sudonaka

iguano

 (3 left by NASA, 2 by Russia, and a recent one from India).

 (Laser Ranging Retroreflector) and is located at 

The Laser Ranging Retroreflector (LRRR) was the first ever deployable lunar laser ranging experiment. It was carried on Apollo 11 as part of the Early Apollo Scientific Experiments Package

The LRRR consists of a series of corner reflectors set within a panel. Laser beams sent from Earth are bounced off the retroreflector and the timing of the return signal can be used to measure the distance from the signal source to the reflector.

 more about how they send lasers and measure the time it takes for the laser to bounce back from those retroreflectors.

How many people here believe that man did go to the moon?

You don't have to trust anyone.

[There are at the moment 6 retroreflectors on the moon](https://en.wikipedia.org/wiki/List_of_retroreflectors_on_the_Moon) (3 left by NASA, 2 by Russia, and a recent one from India).

![](https://imgprxy.stacker.news/2RB9RRIkvPpeHYL2S6Hi4Oei6uXY9H4z_Dqwl0kA-xM/rs:fit:600:500:0/g:no/aHR0cHM6Ly91cGxvYWQud2lraW1lZGlhLm9yZy93aWtpcGVkaWEvY29tbW9ucy90aHVtYi8wLzA4L0Fwb2xsb18xMV9MdW5hcl9MYXNlcl9SYW5naW5nX0V4cGVyaW1lbnQuanBnLzE5MjBweC1BcG9sbG9fMTFfTHVuYXJfTGFzZXJfUmFuZ2luZ19FeHBlcmltZW50LmpwZw)

The one from Apollo 11 is the [LRRR](https://en.wikipedia.org/wiki/Laser_Ranging_Retroreflector) (Laser Ranging Retroreflector) and is located at [Mare Tranquillitatis](https://en.wikipedia.org/wiki/Mare_Tranquillitatis).

![](https://imgprxy.stacker.news/DEuqrS8Kxzfw4gX4KugW0wqStvgSIxoFiIPaQ74oVzg/rs:fit:600:500:0/g:no/aHR0cHM6Ly9pLmltZ3VyLmNvbS9lNk5XWGhGLnBuZw)

> The Laser Ranging Retroreflector (LRRR) was the first ever deployable lunar laser ranging experiment. It was carried on Apollo 11 as part of the Early Apollo Scientific Experiments Package
> 
> The LRRR consists of a series of corner reflectors set within a panel. Laser beams sent from Earth are bounced off the retroreflector and the timing of the return signal can be used to measure the distance from the signal source to the reflector. 

![](https://imgprxy.stacker.news/tJl5i-Vykr8OrSPhhGFGiijOtfbVLWIaHocOz3fI71Q/rs:fit:600:500:0/g:no/aHR0cHM6Ly93d3cubmFzYS5nb3Yvc2l0ZXMvZGVmYXVsdC9maWxlcy90aHVtYm5haWxzL2ltYWdlL2xhc2VyLmpwZw)

You can read [here](https://www.nasa.gov/feature/goddard/2020/laser-beams-reflected-between-earth-and-moon-boost-science) more about how they send lasers and measure the time it takes for the laser to bounce back from those retroreflectors.

