“Although Earth was originally created from the Sun (as part of the ecliptic plane of debris and dust that circulated around the Sun 4.5 billion years ago), our Sun is barely hot enough to fuse hydrogen to helium, observed physicist Michio Kaku in Parallel Worlds: A Journey through Creation, Higher Dimensions, and the Future of the Cosmos. “This means that our true “mother” sun was actually an unnamed star or collection of stars that died billions of years ago in a supernova, which then seeded nearby nebulae with the higher elements beyond iron that make up our body. Literally, our bodies are made of stardust, from stars that died billions of years ago.”
What If History’s Brightest Supernova Exploded In Earth’s Backyard?
In 2015, the automated telescopes in Ohio State’s ASASSN network saw the peach-fuzz blob of a distant galaxy. By June 2015, that galaxy was gone, all of its stars outshone by a piercing blue point, writes Joshua Sokol in The Atlantic. “The explosion, ASASSN-15lh, at the too-close-for comfort distance of the star Arcturus, is a few hundred times brighter than your garden-variety supernova, and two or three times brighter than the previous record holder. It’s in a class by itself,” says Sokol. In addition to the visible light, the exploded star would hang as a blinding point in our sky, pouring X-rays, gamma rays, and hard ultraviolet radiation into Earth’s atmosphere, obliterating its ozone layer.
In 1996, astronomer Brian Fields and his then adviser listed out the radioactive elements blasted into space by a supernova that you might be able hunt down on Earth, reports Sokol. A supernova close enough to leave a trace, they reasoned, might also have been close enough to pose a serious threat to life. “If we were really lucky we could connect it to a mass extinction,” said Fields, now of the University of Illinois. “That’s sort of the Holy Grail, or the unholy grail, of the field.”
Capable of Wiping Human Civilization Off the Face of the Earth
“We see supernovas in other galaxies all the time. Through a telescope, a galaxy is a tiny smudge. Then, all of a sudden, a star-like object appears, emitting enough light to overshadow an entire solar system, even a galaxy,” says geoscientist Robert Brakenridge, a senior research associate at the Institute of Arctic and Alpine Research (INSTAAR) at the University of Colorado, Boulder about a new study that suggests that a very nearby supernova could be capable of wiping human civilization off the face of the Earth. But even from farther away, these explosions may still take a toll, bathing our planet in dangerous radiation and damaging its protective ozone layer.
Releases as Much Energy as the Sun During its Entire Lifetime
Massive supernova explosions can release as much energy as the sun will during its entire lifetime may have left traces in Earth’s biology and geology. A new study probes the impacts of supernovas, some of the most violent events in the known universe. In the span of just a few months, a single one of these eruptions can release as much energy as the sun will during its entire lifetime spreading life-giving elements –helium, carbon, oxygen, iron, nickel-across the universe.
Searching for Cosmic Fingerprints
To study those possible impacts, Brakenridge searched through the planet’s tree ring records for the fingerprints of these distant, cosmic explosions. Although far from conclusive, his findings suggest that relatively close supernovas could theoretically have triggered at least four disruptions to Earth’s climate over the last 40,000 years. “These are extreme events, and their potential effects seem to match tree ring records.”
Brakenridge’s research, reports the University of Colorado, “hinges on the case of a curious atom, carbon-14, also known as radiocarbon, a carbon isotope that occurs only in tiny amounts on Earth. Trees pick up carbon dioxide and some of that carbon will be radiocarbon.”
Carbon-14 –Radiocarbon Atoms on Earth
Scientists have discovered a handful of cases in which the concentration of this isotope inside tree rings spikes–suddenly and for no apparent earthly reason. Many scientists have hypothesized that these several-year-long spikes could be due to solar flares or huge ejections of energy from the surface of the sun. “We’re seeing terrestrial events that are begging for an explanation,” Brakenridge said. “There are really only two possibilities: A solar flare or a supernova. I think the supernova hypothesis has been dismissed too quickly.”
The Last 40,000 Years
Brakenridge noted that scientists have recorded supernovas in other galaxies that have produced a stupendous amount of gamma radiation–the same kind of radiation that can trigger the formation of radiocarbon atoms on Earth. While these isotopes aren’t dangerous on their own, a spike in their levels could indicate that energy from a distant supernova has traveled hundreds to thousands of light-years to our planet. To test the hypothesis, he assembled a list of supernovas that occurred relatively close to Earth over the last 40,000 years. Scientists can study these events by observing the nebulas they left behind. He then compared the estimated ages of those galactic fireworks to the tree ring record on the ground.
The Vela Supernova Remnant
Of the eight closest supernovas studied, all seemed to be associated with unexplained spikes in the radiocarbon record on Earth. Four of these to be especially promising candidates reports Brackenrige, one of which a former star in the Vela constellation, which once sat about 815 lightyears from Earth, that went supernova roughly 13,000 years ago. Not long after that, radiocarbon levels jumped up by nearly 3% on Earth.
The NASA mosaic at the top of the page is centered on the glowing filaments of the Vela Supernova Remnant, the expanding debris cloud from the death explosion of a massive star. Light from the supernova explosion that created the Vela remnant reached Earth about 11,000 years ago, reports NASA — “In addition to the shocked filaments of glowing gas, the cosmic catastrophe also left behind an incredibly dense, rotating stellar core, the Vela Pulsar. Some 800 light-years distant, the Vela remnant is likely embedded in a larger and older supernova remnant, the Gum Nebula.”
Scientists still have trouble dating past supernovas, making the timing of the Vela explosion uncertain with a possible error of as much as 1,500 years. It’s also not clear what the impacts of such a disruption might have been for plants and animals on Earth at the time. But Brakenridge believes that the question begs for more research.
“What keeps me going is when I look at the terrestrial record and I say, ‘My God, the predicted and modeled effects do appear to be there.'”