U.S. residents within the path of totality have just two days remaining before the Great American Eclipse takes place. But there could be a day when the world will witness the last total eclipse of the sun ever. When might this final eclipse take place, and why will eclipses become a thing of the past, as scientists are suggesting in a new study?
According to NASA’s Great American Eclipse portal, solar eclipses were first recorded over 5,000 years ago, when Irish Neolithic astronomers carved in stone their account of the November 30, 3340 BCE eclipse. These events were once thought to be bad omens, but as time passed, they grew to be stunning spectacles that anyone can view without apprehension. That’s going to be the case on Monday, as America gears up for its first coast-to-coast total solar eclipse in almost a century. But scientists fear that there might be a time when the world won’t be able to witness solar eclipses anymore.
As explained on a new paper from NASA, the world’s last total solar eclipse will likely happen in about 563 million years from now. This is because the moon moves by an average of 1.5 inches (3.8 centimeters) away from Earth each year, and has been doing so since it first formed several billions of years ago, at a time when it would have been much more visible in the night sky. In other words, the moon becomes smaller and smaller as we see it here on Earth, and with its constant movement away from our planet, there would come a time when it would be too small to block out the sun to cause a total solar eclipse.
On the other hand, there are some other schools of thought when it comes to predicting when the world’s last total solar eclipse will take place. According to Popular Mechanics, British astronomer Jean Meeus wrote in his book, More Mathematical Astronomy Morsels, that there could be a period of “on-and-off total solar eclipses” beginning about 620 million years from now, due to unusual changes in the orbits of both the Earth and the moon. He believes that the final total solar eclipse might be seen about 1.2 billion years from now.
Popular Mechanics added that the world’s last total solar eclipse might be a blink-and-you-miss it affair, lasting “only seconds or less,” as the moon won’t just be smaller to the human eye, but also blocking sunlight less frequently and for progressively less time.
Although scientists are forecasting the eventual end of total solar eclipses, that doesn’t mean that the world will no longer be witnessing any more solar eclipses of any kind. Annular solar eclipses, or events where the sunlight is shown as a ring surrounding the moon’s circumference, are expected to become more common with the passing of time, just as total solar eclipses become fewer and farther in-between.
Writing for Forbes, astrophysicist and author Ethan Siegel offered his own prediction that the world’s last total solar eclipse will come 570 million years from now. He believes that the final “hybrid eclipse,” or an eclipse that may appear as total or annular depending on which part of the world you’re in, might happen about 80 million years after that final total solar eclipse.
“Beyond that point, the moon will no longer be close enough to Earth at any point in its orbit to have its shadow fall on our surface,” Siegel explained.
“From that moment onward, the only way to see a total solar eclipse will be to take to the skies, or to soar in space itself, where we can find ourselves in the moon’s shadow once again.”
As far as our lifetimes are concerned, Monday’s Great American Eclipse definitely won’t be the last one we’ll be seeing or reading about. As Popular Mechanics noted, total solar eclipses will likely be commonplace for many, many generations of humanity to come. Still, the moon’s slow but steady movement away from Earth guarantees that the world will have a last total eclipse of the sun, even if it may happen several hundreds of millions of years in the future, at the very least.
[Featured Image by Hideo Fukushima/National Astronomical Observatory of Japan via Getty Images]