NASA's Hubble Space Telescope reached a significant milestone on September 19, completing its 200,000th orbit around Earth. Since its launch in 1990, Hubble has traveled over 5 billion miles (8 billion kilometers) and has conducted more than 1.7 million scientific observations. This long-running mission continues to provide valuable insights into the universe, even as it approaches its 37th year in space. On the day of its 200,000th orbit, Hubble focused on a specific scientific task: measuring the expansion rate of the universe, known as the Hubble constant. The observation involved tracking the reappearance of a supernova called Athena, which was first detected by NASA's James Webb Space Telescope in 2025. This type of cosmic event, a massive explosion of a dying star, can be observed multiple times on Earth due to the bending of light by massive objects in space. In the image captured by Hubble, the massive galaxy cluster MACS J0417, located at the left center, acts as a gravitational lens. This phenomenon occurs when the gravity of a massive object, like a galaxy cluster, bends and magnifies the light from more distant objects behind it. As a result, light from Athena can take different paths to reach Earth, causing the same supernova event to be seen multiple times, sometimes months or even years apart. Scientists expect Athena to reappear between now and early March 2027. Tracking these reappearances helps researchers better understand the mass of the galaxy cluster and refine their knowledge of how fast the universe is expanding. Despite being in space for over three decades, Hubble remains a vital tool for astronomers. Its ability to observe ultraviolet and visible light complements the capabilities of newer telescopes like the James Webb and the upcoming Roman Space Telescope. Due to its continued scientific value, the demand for Hubble's observing time remains high, with astronomers requesting about seven times more time than is available each year. Hubble continues to make observations around the clock, and real-time tracking of these observations is available on NASA's website.