Read: A dazzling quarter century of exoplanet discovery

Haswell hypothesized that some of the eroded material, instead of plunging into WASP-12, remained in space, trailing behind the planet like the tail of a comet. Such a stream of debris could absorb some of the star’s light, making the luminous object appear partially dark to telescopes.

The astrophysicist decided to examine other sunlike stars that behaved similarly. Some of them had planets like the one around WASP-12, and they were a breeze to find: Jupiter-sized worlds with tight orbits are some of the easiest planets to detect. But other stars with missing bands of light weren’t known to have planets at all. “If they were hosting really hot, close-orbiting giant planets, then probably they would have been found already,” Haswell said. If these stars had any worlds, they must be low-mass planets, which are more difficult to discern from a star’s blinding glare.

Haswell and her team targeted this population of darkened stars with a telescope instrument that hunts exoplanets the traditional way. Planets can cause their stars to wobble ever so slightly in space, changing the color of the starlight. Astronomers study these tiny shifts for regular patterns, which indicate whether an exoplanet is lurking nearby. Haswell’s hunch was right: Her team found six exoplanets around three different stars, all many light-years from Earth.

The exoplanets, which are probably rocky worlds, range in mass from a few times that of Earth to half that of Jupiter. They’re closer to their stars than Mercury is to the sun. One planet circles its star in five days, a world that would make keeping your New Year’s resolutions much easier, if you didn’t mind the heat. After some millions of years, they’ll be whittled down to nothing—surprisingly quick in astronomy terms.

The planets are far from their stars’ habitable zones, where temperate climes could give liquid water a chance. But they make exciting research targets for scientists curious about the hidden interiors of alien worlds. “When observing a planet from light-years away, there is virtually no way to study the planet's interior composition,” says Jens Hoeijmakers, an astronomer at the Universities of Bern and Geneva in Switzerland, who studies exoplanets but was not involved in Haswell’s research. “By slowly evaporating these planets—or what's left of them—these stars are helping us study what rocky exoplanets are made of, even if they are many light-years away, beyond the reach of spacecraft equipped with scoops, drills, or seismometers.”

In the ’90s, astronomers usually unveiled exoplanet discoveries one by one, careful to temper their excitement should another team of scientists decide to take a look and end up debunking the findings. In the past decade, with the launch of space telescopes specifically designed to search for exoplanets, new finds are announced in batches. The cosmos is sprinkled with planets, some huddled around their stars in groups of eight, like our own. Most of these worlds are invisible to us; astronomers see them only in tiny dips and wobbles of starlight. But with powerful instruments and careful study, scientists can work out their sizes and compositions, and even catch whiffs of water vapor in their atmospheres.