A newly discovered Earth-like planet orbiting a dead star provides insights into Earth’s potential survival after the Sun becomes a white dwarf. Located around 4,000 light-years away, the planet endured its star’s transition from a red giant to a white dwarf, suggesting that planets might survive such stellar transformations.

This Earth-like planet, with a mass approximately 1.9 times that of Earth, is orbiting its white dwarf star at a distance of 2.1 astronomical units (AU), which is about twice the distance between Earth and the Sun. This current position suggests that the planet was once much closer to its star before the star evolved into a red giant, expanding dramatically and potentially engulfing nearby planets.

White dwarfs are the remnants of stars like the Sun after they exhaust their nuclear fuel and go through a phase of instability. During this red giant phase, the star can expand to hundreds of times its original size, dramatically altering the orbits of any surviving planets. Some models predict that Earth may face a similar future when the Sun enters its red giant phase in about 5 billion years, potentially expanding to engulf the inner planets of the solar system, including Mercury, Venus, and Earth. However, this new discovery suggests that survival might be possible under the right circumstances. According to Keming Zhang, an astronomer from the University of California who led the study, “The simplest explanation is that the planet survived through the red giant host star.”

The white dwarf in this system, which has around half the mass of the Sun, shows that it was once similar in size to our Sun before it expelled its outer layers and collapsed into a dense stellar remnant. This star now glows faintly from residual heat rather than nuclear fusion. The fact that the planet survived such a destructive process challenges some of the more pessimistic models that predict Earth’s destruction when the Sun becomes a red giant. Zhang suggests that these models “may be too pessimistic,” adding that "at the end of the day, Earth may just narrowly escape being engulfed, similar to our discovered system."

The discovery of this planet was made possible through a rare phenomenon known as microlensing. This occurs when a massive object, such as a star or a planet, passes in front of a more distant light source, causing the light to bend and magnify due to the gravitational field. In this case, the white dwarf and its planetary companion were detected when they passed in front of a distant background star, located about 26,100 light-years away. The gravitational lensing effect caused the light from the distant star to be magnified by over 1,000 times, enabling astronomers to study the system in remarkable detail.

Zhang explained the process: “The white dwarf lens was nearly perfectly aligned with the background source star during the event, causing it to be magnified by over 1,000 times.” This rare alignment provided the researchers with crucial information about the planet’s mass and orbit, as well as the presence of a brown dwarf orbiting the white dwarf. The brown dwarf, with a mass about 30 times that of Jupiter, is an object that is too large to be classified as a planet but too small to be a star. These objects add to the complexity of the system, providing scientists with valuable data on how planets and sub-stellar objects behave around dying stars.

Microlensing is becoming an increasingly important tool for finding distant planets that are otherwise difficult to detect. As astronomer Joshua Bloom of UC Berkeley noted, “There is a whole set of worlds that are now opening up to us through the microlensing channel, and what’s exciting is that we’re on the precipice of finding exotic configurations like this.”

This discovery has major implications for understanding the future of our own solar system. The planet's current position, at 2.1 AU from its white dwarf star, is roughly where Earth might end up after the Sun completes its red giant phase. This suggests that Earth could potentially survive the violent transformation of the Sun, albeit in a much-altered state. While life as we know it on Earth would likely not endure such extreme conditions, this discovery hints at the possibility that planetary survival is not out of the question.

Zhang points out that models currently disagree on whether Earth will be engulfed by the Sun or pushed out to a more distant orbit. “Models currently disagree whether or not Earth can avoid being engulfed because we do not know the mass loss rate of the red giant sun precisely enough,” Zhang said. This new data, however, offers a more optimistic view, suggesting that planets could indeed survive a star’s death, even if they no longer lie within the habitable zone.

While life on Earth will likely become impossible long before the Sun reaches its red giant phase—due to the gradual increase in the Sun’s heat over the next billion years, which will evaporate Earth’s oceans—there is still a faint glimmer of hope for survival beyond this catastrophic event. As Zhang notes, “By the time the Sun becomes a red giant, the habitable zone will move to around Jupiter and Saturn's orbit, and many of these moons will become ocean planets.” These moons, such as Europa, Callisto, and Ganymede, could provide future havens for humanity as the outer solar system becomes more hospitable.

The discovery of this planetary system also underscores the power of microlensing as a tool for discovering distant exoplanets and studying the systems that orbit dead stars. The research team believes that similar systems will become easier to find in the future, especially with the upcoming launch of NASA’s Nancy Grace Roman Telescope, which is set to specialize in microlensing events and is expected to uncover many more Earth-like planets orbiting distant stars.

“There is some luck involved,” Zhang admitted, “because you'd expect fewer than one in 10 microlensing stars with planets to be white dwarfs.” However, the discovery of this planet, alongside the brown dwarf in the system, adds valuable data to our understanding of how planets behave around stellar remnants. This information will be crucial as scientists continue to explore how planetary systems evolve and survive beyond their stars' main-sequence lifetimes.

The findings give humanity a rare glimpse into the distant future of our own solar system and how planets may navigate the chaos of their star's death, offering both scientific insight and a glimmer of hope for Earth's ultimate survival.