Hz Sky

Observe the radio sky the way astronomers once did! In radio astronomy, measuring the sky’s temperature reveals how radio waves are distributed across our Galaxy and beyond. Unlike visible light, radio observations uncover large-scale structures that cannot be seen by ordinary eyes, including the bright band of the Milky Way across the sky. One of the most influential radio sky maps is the 408 MHz all-sky survey created by Haslam, C. G. T. and collaborators from observations made between the 1960s and 1970s using three major radio telescopes: Effelsberg Radio Telescope, Jodrell Bank Observatory, and Parkes Observatory. This historic survey became a classic reference in radio astronomy. Hz Sky lets you experience this survey yourself. Observe different parts of the sky, collect data, and gradually build your own sky-temperature map. Each observation contributes a small piece, and over time the radio sky emerges step by step — just as real survey work requires patience, coverage, and repetition. Watch the radio sky appear observation by observation. As observations accumulate, the map slowly fills with temperature patterns across the sky, revealing bright regions and the large-scale beauty of radio emission. No prior astronomy knowledge required — learn by observing! A nearly complete map requires more than 9,216 observations. Can you take on the challenge and build the sky for yourself?