With radio telescopes, astronomers can use the light from distant galaxies to illuminate these otherwise invisible areas in space.<\/p>\n
In our study, published today in Publications of the Astronomical Society of Australia<\/a>, we\u2019ve used Australia\u2019s most powerful radio telescope to create the largest and most detailed map of cosmic magnetic fields ever made.<\/p>\n The new map with some of the visible sky features labelled. Giant batteries that control galaxies<\/p>\n Magnetic fields greatly vary across the universe. Extremely dense objects, such as neutron stars and black holes, have magnetic fields thousands of billions times stronger than Earth\u2019s own.<\/p>\n In the space between stars we\u2019ve also measured magnetic fields a million times weaker than Earth\u2019s. Despite their weakness, we know these fields are incredibly important for controlling how galaxies evolve. They act like giant batteries and store huge amounts of energy, slowing down or even preventing the formation of new stars.<\/p>\n But to us, magnetic fields are invisible. To find them in space, astronomers are limited to using light from distant stars and galaxies. That\u2019s because light is a wave of electric and magnetic fields (that\u2019s where the \u201celectromagnetic spectrum<\/a>\u201d gets its name). <\/p>\n As light travels across the universe, it interacts with any magnetic fields it passes through. This will twist the direction the light is waving \u2013 we call this \u201cpolarisation\u201d. So, light waving up and down has a different polarisation to light waving side to side.<\/p>\n Astronomers can catch this polarisation, especially when looking at the sky in radio waves, which are part of the electromagnetic spectrum.<\/p>\n The twisting of the polarisation of light from distant sources as it travels through magnetic fields. Seeing the invisible<\/p>\n Australian telescopes have been at the forefront of both radio astronomy and detecting magnetic fields since their first detection. Murriyang, CSIRO\u2019s Parkes radio telescope, was the first to detect the twisting polarisation of light from magnetic fields beyond Earth in 1962<\/a>.<\/p>\n Ever since, astronomers have been pushing to find more and more sources that show us this twisting light. With enough measurements, we can create a map of magnetic fields in the universe.<\/p>\n Each point in the map is an object detected by our telescope, and the object\u2019s light has illuminated the magnetic fields between us and that distant source. The more sources we detect, the more detailed our map becomes. <\/p>\n The last large map of magnetic fields was made in 2009<\/a>. It has not seen a true successor in the intervening 17 years, limiting the depth and scope of the inquiries astronomers have sought to answer. <\/p>\n Across different areas of the universe, including our own Milky Way galaxy, we\u2019re yet to understand the full strength and structure of cosmic magnetic fields. Not only do we not know how they came to exist, we don\u2019t know how they\u2019ve changed across time since the Big Bang. <\/p>\n To begin solving these problems, we need a new class of radio telescope.<\/p>\n CSIRO\u2019s ASKAP radio telescope at Inyarrimanha Ilgari Bundara, the CSIRO Murchison Radio-astronomy Observatory on Wajarri Yamaji Country. A telescope built for speed<\/p>\n Radio astronomy is currently undergoing a revolution as the SKA Observatory is being built<\/a> in South Africa and Australia. In preparation, a generation of telescopes, known as SKA precursors and pathfinders, are already operating around the world.<\/p>\n The ASKAP radio telescope is one of these precursors. Located at Inyarrimanha Ilgari Bundara, the CSIRO Murchison Radio-astronomy Observatory on Wajarri Yamaji Country in Western Australia, it\u2019s made up of 36 12-metre dishes. These dishes can each see a huge section of the sky at once, giving astronomers an ultrawide view of the universe.<\/p>\n The flagship project to make a map of the universe\u2019s magnetic fields is known as the Polarisation Sky Survey of the Universe\u2019s Magnetism (POSSUM<\/a>).<\/p>\n In preparation for it, the telescope\u2019s team produced the Rapid ASKAP Continuum Surveys (RACS<\/a>). It\u2019s like making an atlas of the universe<\/a>. The most recent versions of these surveys have identified nearly 4 million distant galaxies, with about 2 million having never been seen before.<\/p>\n The magnetic sky<\/p>\n Our new map, called SPICE-RACS<\/a>, has come from a collaboration between the two survey teams.<\/p>\n Our goal was to look towards every galaxy found by RACS, and observe the signs of changing polarisation caused by magnetic fields. Using the latest release of the survey, we found 350,000 galaxies of the original 4 million we could use for this. <\/p>\n Our collection of sources is nearly ten times larger than the previous largest, and five times larger than all observations ever combined together. As a result, we\u2019ve obtained the largest and most detailed map to date.<\/p>\n![\"\"](\"https:\/\/www.newsbeep.com\/nz\/wp-content\/uploads\/2026\/06\/file-20260602-71-ntgbcl.PNG\")
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\n Alec Thomson et al.<\/p>\n![\"\"](\"https:\/\/www.newsbeep.com\/nz\/wp-content\/uploads\/2026\/06\/file-20260602-57-a3q74z.png\")
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\n Emma Alexander<\/a>, CC BY<\/a><\/p>\n![\"\"](\"https:\/\/www.newsbeep.com\/nz\/wp-content\/uploads\/2026\/06\/file-20260602-57-oyy7xo.jpg\")
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\n CSIRO<\/p>\n
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