The Sun is used to having plenty of personal space, given that its nearest stellar neighbor, the Alpha Centauri system, is located about four light years away. While that's not very distant in cosmic terms, it's wide enough for our solar system to not be influenced by these alien stars.
But in about 1.3 million years, a star named Gliese 710, which is about 60 percent as massive as the Sun, is projected to interrupt the Sun's hermitude by crashing right on through the far-flung reaches of the solar system. While astronomers have been aware of this stellar meetup for years, new observations from the European Space Agency's Gaia satellite, released on Thursday, have constrained the trajectory of Gliese 710's impending visit, and charted out nearly 100 other upcoming close encounters with wandering stars.
According to the Gaia team, Gliese 710 will swoop through the Oort cloud, a vast shell of icy debris at the outer limits of the solar system, at a distance of roughly 90 light days, or 1.4 trillion miles. To put that into perspective, the star will be about 16,000 times farther from the Sun than Earth.
That may sound like a good stretch of space, but it is well within the boundaries of the Sun's domain. During the encounter, Gliese 710 will shine nearly three times brighter in Earth's skies than Mars. It could also spitball comets and ice worlds from the distant reaches of the solar system toward Earth, increasing the likelihood of deadly impacts.
Of course, we have over one million years to prepare for this disruptive passerby, but it's worth noting that it is far from the only star Gaia has identified as a potential trouble-maker.
Gaia, launched in 2013, has calculated the positions, magnitudes, parallaxes, and proper motions of millions of stars during its quest to create the most precise catalogue of the Milky Way's stellar population. Using this enormous dataset, scientists have plotted out the trajectories of 300,000 stars over the next five million years, and discovered that 97 of them will breach a radius of 93 trillion miles around the Sun.
Of those stars, 16 will travel within 37 trillion miles around the Sun, which is the rough distance at which stars begin to impact the solar system (though the extent to which they cause a ruckus depends on their mass and velocity).
It won't be the first time the Sun has had its personal space invaded by a stellar tourist. Only 70,000 years ago, around the time early humans were suffering from major volcano-induced endangerment, a dwarf star checked out the scene in the Oort cloud. Some scientists have even suggested that repeated encounters with nearby "death stars" are responsible for the cycle of mass extinctions on Earth, though the theory is controversial.
It goes to show that even the Sun has to deal with uninvited guests dropping by and causing mayhem. But now, thanks to Gaia, at least we can get an early heads-up to prepare for these otherworldly encounters.
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