Scientists have achieved a groundbreaking feat by transmitting precise time signals through the air using laser technology. The experiment involved directing laser pulses over a distance of 150 km, from Mauna Loa volcano to Haleakala peak. Despite the faintness of the pulses, they successfully transmitted highly accurate time signals between these far-flung locations, making them suitable for future space missions. This achievement, accomplished by a team including scientists from NIST, has the potential to enable time transfer from the ground to geosynchronous orbit satellites, positioned 36,000 km above Earth's surface. The method offers unparalleled precision, surpassing current satellite approaches by a factor of 10,000. Additionally, the system remains robust in the face of atmospheric disturbances, thanks to its minimal timing signal strength requirement. This breakthrough opens up exciting possibilities for coordinating distant devices. Existing microwave-based methods fall short in conveying precision over long distances for comparing optical atomic clocks across continents. However, the new approach allows optical clocks on opposite sides of the planet to be linked through geosynchronous satellites, preserving precision. This advancement supports redefining the SI second to an optical standard and enables a range of fundamental physics measurements, including investigations into dark matter and tests of general relativity. The benefits extend beyond optical atomic clocks. Synchronising widely separated sensors holds promise for advancing applications like very long baseline interferometry (VLBI), which can improve imaging of far-away planets and black holes. Laura Sinclair, a physicist at NIST, emphasised the unprecedented distributed coherent sensing made possible by this technology. Sensor arrays could observe both space and Earth, relying on highly accurate optical clocks for connectivity. The success of the experiment relied on the team's innovative creation, the time programmable frequency comb, which represents a significant advancement in frequency comb technology. The expanded functionality of this frequency comb enabled the transmission and reception of the high-frequency time signal. Looking ahead, the NIST team aims to optimise the system further by reducing its size, weight, and power requirements, as well as adapting it for use on moving platforms. These advancements have the potential to revolutionise time signal transmission and make a significant impact across various scientific disciplines.