The Universe is like a giant balloon, inflated by dark energy. Usually, this invisible pump works smoothly, but it could suddenly speed up, and the balloon would burst in a Big Rip. For a long time, the pace of inflation was gauged by the redshift of light from distant galaxies (discovered by Edwin Hubble), the flashes of supernovae (for which Adam Riess and Saul Perlmutter won the Nobel Prize), and the ancient radiation from the Big Bang. But that light traveled for billions of years and can't tell us what the pump is doing right now. Planets, however, like bright dots on the balloon, sense changes instantly: any acceleration of expansion immediately distorts their orbits through gravity.

Analysis of the trajectories of Earth, Mars, and especially Saturn has shown: even if the destructive mode kicked in today, catastrophe is at least 30 years away. This timeline comes from precise measurements and the expansion rate that underpins the cosmological model. It's astonishing that the density of dark energy is negligible (within Earth's volume, it's comparable to a grain of sand) yet this 'grain of sand' decides the fate of everything. And before the end arrives, its harbingers will appear right here in the Solar System.