{"copyright":"Joao Yordanov Serralheiro","date":"2025-09-13","explanation":"The steerable 60 foot diameter dish antenna of the One-Mile Telescope at Mullard Rad io Astronomy Observatory, Cambridge, UK, is pointing skyward in this evocative n ight-skyscape. To capture the dramatic scene, consecutive 30 second exposures we re recorded over a period of 90 minutes. Combined, the exposures reveal a backgr ound of gracefully arcing star trails that reflect planet Earth's daily rotation on its axis. The North Celestial Pole, the extension of Earth's axis of rotatio n into space, points near Polaris, the North Star. That's the bright star that c reates the short trail near the center of the concentric arcs. But the historic One-Mile Telescope array also relied on planet Earth's rotation to operate. Expl oring the universe at radio wavelengths, it was the first radio telescope to use Earth-rotation aperture synthesis. That technique uses the rotation of the Eart h to change the relative orientation of the telescope array and celestial radio sources to create radio maps of the sky at a resolution better than that of the human eye.","hdurl":"https:\/\/apod.nasa.gov\/apod\/image\/2509\/StarTrailsOne-M ileRadioTelescope2100.jpg","media_type":"image","service_version":"v1","title":" Star Trails over One-Mile Radio Telescope","url":"https:\/\/apod.nasa.gov\/apod\ /image\/2509\/StarTrailsOne-MileRadioTelescope1050.jpg"}
