A very “shy” aluminum ion, according to the NIST. What are optical atomic clocks? To track the ions’ vibrations, atoms are cooled to near absolute zero (−459.67 degrees Fahrenheit), then measured using lasers that count their vibrations. The newly modified ion trap for NIST’s aluminum ion clock, with an inset showing a CCD image of the aluminum-magnesium ion pair. Ultimately, the more-than-2-mile-long laser beam allowed researchers to measure ion vibrations for a full second, versus the previous 150 millisecond record.