Cause unknown: A gigantic wave is travelling through the Milky Way
Countless stars in the Milky Way are being raised and lowered by a gigantic wave. This was discovered using data from the Gaia space telescope.
The shifted positions of the stars are marked in red and blue, the arrows show their direction of movement
(Image: ESA/Gaia/DPAC, S. Payne-Wardenaar, E. Poggio et al (2025))
A gigantic wave is traveling through the Milky Way, causing countless stars to rise or fall by considerable distances. This was discovered by a research group using data from ESA's Gaia space telescope. It resembles a pond whose water surface has been made to vibrate by a stone, except that the gigantic wave in the Milky Way extends over large parts of the outer galaxy disc. Its cause is completely unclear, but it is conceivable that it is due to a collision with a dwarf galaxy, writes the research group. It is also possible that it is connected to a significantly smaller wave-like gas structure, which has been baptized the "Radcliffe Wave." However, both still need to be researched.
Not the first wave in the Milky Way
The visualizations of the measurement results not only clearly show the wave-shaped bulges at the edges of the Milky Way, according to the ESA, the data also make it clear that the stars move slightly offset in exactly the same way as one would expect from a wave. The stars in front of the wave glide strongly upwards, while they sink visibly behind it. At the same time, however, the ESA points out that the movements are extremely slow: What we see resembles a photo of a la-ola in a stadium, with some people standing and others sitting, while those in between can be seen to be standing up or sitting down. The fact that the structure not only looks like a wave but also behaves like one is particularly exciting.
It was only a year and a half ago that the so-called “Radcliffe wave” was discovered thanks to the extremely precise data from Gaia. This is a 9000-light-year-long structure of interconnected gas clouds that moves in waves. It is unclear how it was created; there are only hypotheses. It is also not clear whether the significantly larger wave in the Milky Way is related to this. However, it moves stars that are 30,000 to 65,000 light years apart, which is two-thirds of the diameter of our home galaxy. It is possible that even more precise data from Gaia, which is due to be published at the end of 2026, will provide further insights.
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ESA's revolutionary Gaia space telescope, whose data made the discovery possible in the first place, was switched off at the beginning of the year due to running out of fuel. At the time, Gaia was said to have “redrawn the entire picture of the Milky Way,” and the discovery now proves that this has not yet been completed. Using a gigapixel camera, the instrument continuously photographed the starry sky for more than ten years. As it traveled around the sun with the Earth, the precise measurement data made it possible to determine the position of billions of stars with increasing accuracy thanks to the so-called parallax measurement. This laid the foundation for unforeseeable discoveries such as the giant wave. This is presented in astronomy and astrophysics.
(mho)
