In the boundless darkness of the Galaxy, two tiny but incredibly dense stars whirl around each other at furious speed. Their orbital period is measured in minutes. These white dwarfs — the cooled cores of once-bright suns — continuously distort the fabric of spacetime, producing faint but steady ripples that spread out in all directions. Astronomers have long known that the future space observatory LISA will hear these signals. Now something far more surprising has come to light. If a planet orbits such a pair, its presence leaves a subtle but recognizable imprint on the wave.
Two papers published on 10 November 2026 year in the journal The Astrophysical Journal, describe in detail how this works. The first was written by Casey McGrath, a postdoctoral fellow at the University of Maryland and NASA's Goddard Space Flight Center. The second is the result of a collaboration between McGrath, Mary Anne Limbach of the University of Michigan, Scott Noble of Goddard, and Vincent Kofman. The idea originated back in 2008 year with the Japanese astronomer Naoki Seto, but only now has it been calculated with the necessary precision.
The mechanism resembles the classic radial velocity method used to discover exoplanets by the wobble of a star. Only here, instead of light, gravitational waves do the work. A double white dwarf on its own emits an almost monochromatic signal — a pure "carrier" frequency. A planet makes the whole system wobble slightly. This motion adds Doppler modulation: sidebands appear next to the main frequency, as in radio communication. These "messages" conceal information about a distant world. LISA will be able to detect a planet with the mass of Jupiter at a distance of thousands of light-years.
The Milky Way contains about ten million such close pairs of white dwarfs with periods of less than an hour. LISA, which the European Space Agency and NASA are preparing to launch in the mid-2030s, should resolve roughly ten thousand individual systems. No planet has yet been found around a double white dwarf. Any discovery would mark the beginning of a new population.
To separate real planets from false signals, the scientists propose confirmation with the James Webb telescope. A planet around white dwarfs produces an excess of infrared radiation that Webb's instruments are capable of noticing at distances of up to several hundred light-years. In a test calculation for a system similar to the known ZTF J2243+5242, LISA detects an object slightly smaller than Jupiter, while Webb detects a planet of about five Jupiter masses.
The three LISA spacecraft will form an equilateral triangle with a side of 2,5 million kilometers. Laser beams will measure changes in distance smaller than the diameter of a helium atom. These tiny oscillations will become the voice of distant worlds.
Gravitational waves know no barriers. They pass through dust, gas and entire star clusters, carrying information about what ordinary light conceals. That is their power: they reveal the Universe as it is — bound by invisible threads, where even fading stars continue to create worlds, and spacetime preserves their traces. We live in a cosmos where every movement, even the most distant, leaves a trace, and humanity is learning to read those traces.
