Today, April 24, 2020, the Hubble Space Telescope celebrates its 30th birthday in orbit, and what an incredible 30 years they have been. The observatory has peered into space like no other mission before, providing data that has changed our understanding of the universe and dazzled us with the beauty of the cosmos.
The achievements of Hubble cannot be overstated. Its first image, snapped on May 20, 1990, was a photo of a binary star, HD96755, in the open cluster NGC 3532, also known as the Pincushion Cluster, about 1,300 light-years away from us. Over the following three decades, the telescope has delivered over 1 million observations, from planets in the Solar System to galaxies in the first billion years of the universe.
Many facts we now take for granted were only discovered or confirmed thanks to the keen eye of Hubble and the incredible work of scientists across the world. The telescope confirmed the existence of supermassive black holes at the core of every galaxy and its observations of a particular type of supernova proved that the universe continues to expand faster and faster.
Hubble was also instrumental in estimating crucial properties of the Milky Way, such as its mass and size. The data collected, combined with the observations of the European Space Agency’s Gaia, puts the mass of the Milky Way at about 1.5 trillion Suns and 129,000 light-years in diameter. Hubble's observations are not just about the wider mysteries of the cosmos, it has also discovered plenty within our Solar System; from observations of aurorae on Jupiter’s moon Ganymede to the discovery of the fifth moon of Pluto. It even discovered Arrokoth, the most distant world ever explored by humanity.
Much of science is about predicting phenomena and making observations to see if the predictions are correct. A notable prediction that was proven to be true was the Refsdal supernova. This event took place in a galaxy over 10 billion light-years away with a large cluster of galaxies between us and this object (a crucial fact). The clusters warp space-time to such a degree that multiple images of the more distant galaxy that hosts of Refsdal supernova were captured. Since those images were not from the same time, astronomers saw the explosion several times. The last image of it taken on December 11, 2015, was snapped by Hubble. These observations allowed us to test models of how space-time is warped by gravity.
Hubble’s most recent refurbishment was in 2009 and since then it has developed some problems due to its impressive age. However, thanks to the work of the Hubble team it continues to perform well, and will hopefully help us unravel the mysteries of the cosmos for a long time to come.
If you want to join in the celebrations, check out this tool to find out what Hubble photographed on your birthday.