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 scenein 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.