How sure can we be of the distances in the solar system?

AI Thread Summary
The discussion centers on the accuracy of measuring distances in the solar system and the reliability of the speed of light (SOL). Current methods include shining lasers at lunar mirrors and timing the return, raising questions about circular measurements of SOL. Advanced techniques, such as interferometry, have significantly improved the precision of SOL measurements, which is now defined as exactly 299,792,458 m/s. The successful landing and orbiting of probes around various planets lend credibility to the accuracy of our distance estimates in the solar system. Understanding these measurements is crucial, as they underpin much of modern scientific knowledge.
Warp10
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And directly related to that: How can we be sure of the speed of light? I've been searching for a good answer as to how we measure the SOL and am yet to have someone give me a solid explanation. Today we shine a laser at a mirror on the moon and time how long it takes to get back. What it sounds like to me is: we use the SOL to measure a distance that we use to measure the SOL.

I've also heard that we have a device that measures how many times light bounces between 2 points within 1 meter. If I am not mistaken that's 3x10^8 times in 1 sec.

This to me seems like a pretty important thing to know considering our science is pretty well based on the SOL.
 
Astronomy news on Phys.org
Physicists have been measuring the speed of light with ever-improving accuracy for quite some time now. Interferometry-based experiments provided incredibly accurate measurements. Nowadays, with the speed of light defined as 299,792,458 m/s (exactly), those same interferometry-based experiments provide ever-refined means to establish a baseline for the meter.
 
Having landed probes on, or put them in orbit around, most of the planets in the solar system is compelling evidence our distance estimates are pretty accurate.
 

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