Look up at Proxima Centauri or Sirius on a clear night and you’re looking at more than two points of light. In October 2024, astronomers working with data from the eROSITA X-ray telescope mapped something genuinely new: channels of hot, low-density plasma extending from our solar system’s neighborhood toward both of those stars, real structures published in a real peer-reviewed journal, not the plot device they sound like.
These aren’t wormholes, and nothing about them lets a spacecraft travel faster. What they are is a genuine discovery about the shape of the space immediately around us, made by a Max Planck Institute for Extraterrestrial Physics team analyzing eROSITA’s first all-sky survey, published in Astronomy & Astrophysics. The findings open real questions about our galactic neighborhood’s violent history, and invite some speculative ones about what that history might have meant for life on Earth.
The Telescope That Found Them
eROSITA, short for extended ROentgen Survey with an Imaging Telescope Array, launched in 2019 aboard the Spektr-RG mission, a joint Russian-German effort, and now orbits roughly 1.5 million kilometers from Earth at the L2 Lagrange point. From there it scans the sky for soft X-rays, the kind Earth’s own atmosphere absorbs before they ever reach the ground, which is why this picture only came into focus once a space-based instrument was actually built to look for it.
Soft X-rays aren’t background noise. They’re signatures of hot plasma, supernova remnants, and other high-energy events, and because they’re absorbed so quickly by intervening gas, any that reach a detector must have originated relatively close by, within a few hundred light-years at most. eROSITA’s first full survey, eRASS1, gave researchers the cleanest dataset yet for tracing that local signal, cleaner than anything the earlier ROSAT mission could produce. The team split the sky into roughly 2,000 regions, analyzed the spectrum from each, and combined the results with archival ROSAT data and known distances to nearby molecular clouds. What emerged was a three-dimensional, publicly explorable model, and it wasn’t the tidy sphere textbooks often imply.
The Bubble We Already Knew We Lived In
Our solar system sits inside what astronomers have called, for about half a century, the Local Hot Bubble: a roughly 300 light-year cavity of rarefied plasma, mostly hydrogen, running about ten times less dense than the surrounding interstellar medium, somewhere around 0.5 atoms per cubic centimeter in most of the bubble and as low as 0.1 in its hottest core. Despite temperatures between 1.2 and 1.4 million Kelvin, this isn’t heat in any way you’d feel. The particles carry enormous energy individually, but they’re spread so thin that collisions, and the transfer of that heat, are rare. It’s hot in the physicist’s sense, not the campfire sense.
The new 3D reconstruction shows the bubble bulging toward the galactic poles, where there’s less dense gas to push against, giving it a bipolar shape similar to some nebulae. It’s also asymmetric in temperature: roughly 1.2 million Kelvin in the northern galactic hemisphere against 1.4 million in the south, a gradient the researchers attribute to uneven heating from sequential supernova explosions rather than one clean, simultaneous blast.
How a Cluster of Dying Stars Built a Cavity
The bubble’s origin traces to a cluster of supernovae, somewhere between 6 and 15 of them by current estimates, detonating in sequence roughly 10 to 14 million years ago, likely within a stellar nursery disturbed by a shock wave propagating out from one of the galaxy’s spiral arms. Each explosion pushed outward at speeds approaching light, and as the individual shells expanded and merged, they swept the surrounding cooler gas outward, leaving the hot, sparse interior we sit in today. The bubble’s walls, marked by molecular clouds formed from compressed material, are effectively a fossil record of that ancient violence. Our own Sun only entered this particular cavity around 5 million years ago as it continued its longer orbit around the galactic center, meaning our current position at the hottest, emptiest part of it is closer to a passing coincidence of orbital timing than a fixed cosmic address.
What the New Data Actually Added | Two Tunnels
The genuinely new finding in the 2024 study is a channel of hot, low-density plasma extending from the bubble toward the constellation Centaurus, home to Proxima Centauri, our nearest stellar neighbor at 4.2 light-years. It isn’t a hollow tube; it’s a corridor of thinner, hotter gas punching through the surrounding cooler medium, visible in the X-ray data as a gap where you’d otherwise expect more resistance. A second, previously noted channel points toward Canis Major, home to Sirius, and may connect the Local Hot Bubble to the Gum Nebula or a separate structure called GSH 238+00+09. Together they lend real support to an idea proposed back in the 1970s and difficult to confirm ever since: that hot regions of the interstellar medium aren’t isolated pockets but form a connected, branching network sustained by ongoing stellar feedback across the galaxy.
None of this makes for a shortcut. The interstellar medium, tunnel or not, is so thin that even a slight further drop in density is negligible against the scale involved, Voyager’s own instruments register more resistance from their own antenna emissions than from the medium they’re passing through. What the tunnels do offer is a real, useful way to refine models of galactic evolution, cosmic ray propagation, and the broader structure of the Milky Way’s interstellar scaffolding, work future missions like the planned Athena X-ray observatory are expected to build on directly.
A Genuinely Open Question About Timing
Here’s where the science gets more speculative, and worth flagging as exactly that. The Sun’s entry into the Local Hot Bubble roughly 5 million years ago sits close to a pivotal stretch of hominid evolution. Some researchers have floated the idea that increased cosmic ray exposure in a low-density region like this one could plausibly influence mutation rates, a real, testable hypothesis, but one that currently has correlation and no demonstrated mechanism connecting the two events. Supernovae themselves cut both ways for life: they can sterilize nearby systems outright, but they’re also the source of heavier elements like iron and oxygen that planets and biology both depend on. Our position inside this particular remnant may turn out to be incidental rather than causal, an open question rather than a settled one.
Where Sirius and the Dogon Enter the Story
No genuine astronomical finding stays free of extra mythology for long, and the tunnels are no exception. Online discussion has already recast them as alien highways, leaning partly on Sirius’s real prominence in ancient Egyptian religion and in the Dogon people of Mali’s own oral tradition, which some writers claim described the invisible white dwarf companion Sirius B long before telescopes could have detected it.
That specific claim doesn’t hold up well under later scrutiny. Anthropologist Walter van Beek’s independent fieldwork among the Dogon in the 1990s found no consistent evidence the broader community actually held this knowledge, and found real reason to suspect contamination from earlier contact between Dogon informants and Western astronomers and missionaries who had known about Sirius B since the 19th century. Sirius’s brightness alone is more than enough to explain why it recurs so often across independent mythologies without needing an external source. Nothing in the eROSITA data or the published research suggests engineering of any kind behind either tunnel; they’re a natural, if genuinely striking, consequence of stellar physics playing out over millions of years.
What This Actually Changes
The real value here isn’t a travel route, it’s a better map. We’re not sitting in isolated emptiness so much as embedded in a web of thin, hot plasma shaped by millions of years of stellar violence, some of it still measurably connecting us to our nearest stellar neighbors. As eROSITA’s successors, Athena among them, extend this kind of mapping further, the picture of exactly how connected that web really is should only get sharper.
