Creating An Ultra-Stable Lunar Clock With A Cryogenic Silicon Cavity Laser

March 4, 2026 by Maya Posch 1 Comment

Phase-coherent lasers are crucial for many precision tasks, including timekeeping. Here on Earth the most stable optical oscillators are used in e.g. atomic clocks and many ultra-precise scientific measurements, such as gravitational wave detection. Since these optical oscillators use cryogenic silicon cavities, it’s completely logical to take this principle and build a cryogenic silicon cavity laser on the Moon.

In the pre-print article by [Jun Ye] et al., the researchers go through the design parameters and construction details of such a device in one of the permanently shadowed regions (PSRs) of the Moon, as well as the applications for it. This would include the establishment of a very precise lunar clock, optical interferometry and various other scientific and telecommunication applications.

Although these PSRs are briefly called ‘cold’ in the paper’s abstract, this is fortunately quickly corrected, as the right term is ‘well-insulated’. These PSRs on the lunar surface never get to warm up due to the lack of an atmosphere to radiate thermal energy, and the Sun’s warm rays never pierce their darkness either. Thus, with some radiators to shed what little thermal energy the system generates and the typical three layers of thermal shielding it should stay very much cryogenic.

Add to this the natural vacuum on the lunar surface, with PSRs even escaping the solar wind’s particulates, and maintaining a cryogenic, ultra-high vacuum inside the silicon cavity should be a snap, with less noise than on Earth. Whether we’ll see this deployed to the Moon any time soon remains to be seen, but with various manned missions and even Moon colony plans in the charts, this could be just one of the many technologies to be deployed on the lunar surface over the next few decades.

A Stylish Moon And Tide Clock For The Mantlepiece

December 2, 2025 by Lewin Day 3 Comments

Assuming you’re not stuck in a prison cell without windows, you could feasibly keep track of the moon and tides by walking outside and jotting things down in your notebook. Alternatively, you could save a lot of hassle by just building this moon and tide clock from [pjdines1994] instead.

The build is based on a Raspberry Pi Pico W, which is hooked up to a real-time clock module and a Waveshare 3.7-inch e-paper display. Upon this display, the clock draws an image relevant to the current phase of the moon. As the write-up notes, it was a tad fussy to store 24 images for all the different lunar phases within the Pi Pico, but it was achieved nonetheless with a touch of compression. As for tides, it covers those too by pulling in tide information from an online resource.

It’s specifically set up to report the local tides for [pjdines1994], reporting the high tide and low tide times for Whitstable in the United Kingdom. If you’re not in Whitstable, you’d probably want to reconfigure the clock before using it yourself. Unless you really want to know what’s up in Whitstable, of course. If you so wish, you can set the clock up to make its own tide predictions by running local calculations, but [pjdines1994] notes that this is rather more complicated to do. The finished result look quite good, because [pjdines1994] decided to build it inside an old carriage clock that only reveals parts of the display showing the moon and the relevant tide numbers.

We’ve featured some other great tide clocks before, like this grand 3D printed design. If you’ve built your own arcane machine to plot the dances of celestial objects, do be sure to let us know on the tipsline!