Only two of the more than 5300 known exoplanets have so far provided evidence of moons in orbit around them. In observations of the planets Kepler-1625b and Kepler-1708b from the Kepler and Hubble space telescopes, researchers had discovered traces of such moons for the first time. A new study now raises doubts about these previous claims. As scientists from the Max Planck Institute for Solar System Research (MPS) and the Sonnenberg Observatory, both in Germany, report today in the journal Nature Astronomy, "planet-only" interpretations of the observations are more conclusive. For their analysis, the researchers used their newly developed computer algorithm Pandora, which facilitates and accelerates the search for exomoons. They also investigated what kind of exomoons can be found in principle in modern space-based astronomical observations. Their answer is quite shocking.

25 years ago, the space probe SOHO (Solar and Heliospheric Observatory), a joint project of ESA and NASA, was launched. Since then, it has been orbiting around our star synchronously with Earth and, thanks to its uniquely unobstructed and multifold view, has shaped our current understanding of the Sun. Despite the increasing competition from more modern space observatories and despite a few technical aches and pains, SOHO's continuous data stream remains invaluable. Actually, the probe’s old age has become an important asset: SOHO is the only solar observatory in space that has accompanied our star through more than two sunspot cycles. Many central questions of solar research can only be answered by such long observation series.