We take a lot of things for granted on our Third Rock from the Sun. We assume that what goes up must come down, that the Earth’s rotation will continue to give us our regular cycle of day and night, and that our annual revolution around the Sun will give us a reason to look forward to pumpkin spice lattes, a.k.a. seasonal changes. If any one of these phenomena were to cease functioning, our daily lives would be in for some big changes. If the Earth stopped orbiting our life-giving star, however, we’d have about 45 days before our world became inhospitable during its inexorable plunge into the Sun.
This phenomenon is known as Earthfall. Though Hollywood favors massive asteroids, Mayan prophecies, rogue planets, and other disasters as a means to bring about the end of the world, for my money, Earthfall is the ultimate terrifying end to all things terrestrial. (And thanks to NASA for these breathtaking pictures of the Sun, which is about as close as we’d like to get.) Here’s a look at how the Earth would change over its roughly two month journey before being torn asunder by the Sun.
The short version:
The detailed breakdown of Earthfall gets a bit more gruesome, and thanks to an excellent write-up from Wired, we can happily bring that to you in honor of Nerdoween. (This short Radiolab chat concerning Isaac Newton’s explanation of freefalling bodies is a fantastic primer for understanding Earth’s orbit.)
On the first day of Earthfall (which sounds like a lyric from the worst holiday song ever), we’d begin our direct descent into the Sun, accelerating due to its gravity on the way and picking up quite a bit of heat due to the increasing intensity of sunlight. By the end of the first week, Earth’s average temperature would have risen by 0.8 degrees Celsius, roughly the same amount average global temperatures have risen since 1880. Three weeks in and we’d really start to feel the heat since global temperatures would reach 35° C (95° F) and crops would start to wither in the planet-wide heat wave.
At just over a month, we’d be 1/5 of the way to the Sun and, at 58° C (137° F), the average global temperature would surpass the hottest recorded temperature on Earth: Death Valley, CA’s 56.7° C (134° F). Air conditioning is a necessity for survival at this point, though the strain on the electrical grid could easily overtax it. In the wilderness, forest fires now spread out of control, insects begin to die in the excessive heat, and so do fish since warmer ocean water contains less available oxygen and more toxic ammonia. Food chains would be in bad shape, save for extreme heat-tolerant scavengers like the Sahara Desert ant, which would have plenty of corpses to feast on.
About 40 days in, we cross Venus’ orbit, and a few days after that, we’ve left the Goldilocks-like habitable zone completely. Our waterways are now literally boiling since the average global temperature exceeds the boiling point of water; steam envelopes the planet and we find that we have become the infamous frog in a pot, except without the frog’s actual ability to simply jump out. Hopefully we’ve found a way off the planet by this point because it now belongs to hyperthermophilic bacteria, fire-tolerant plants, and Tardigrades. But even these hardy products of evolution will shuffle off their mortal coils by Day 54, when Earth’s temperature exceeds 160° C (320° F). Three days later, after crossing Mercury’s orbit and taking up the mantle of “First Rock from the Sun” for one week, Earth’s temperature reaches 200° C.
The final day of Earthfall ends after only 13 hours thanks to the Sun’s immense gravity causing the tidal force to pull the planet into an ovoid shape, allowing magma to erupt through cracks in the Earth’s crust. The morning sees the temperature rise from 800° C to a rock-melting 2,000° C by noon; Earth’s surface is now liquid hot magma. The Sun itself soon fills most of the sky. Earth passes the point of no-return, a line called the Roche radius which, having crossed it, sees the tidal forces overcome Earth’s own gravity, ripping the planet into chunks of melted rock and magma. What it is to burn.
Though this would truly be the End of Days for us Earthlings, Earthfall is unlikely to happen. The planet’s orbit is actually quite stable; not even a collision from an asteroid would stop Earth’s revolution dead or knock enough mass from the planet to bring about a full-stop. It would be relatively easier to increase our speed to an orbital escape velocity of 42.1km/s and shoot off into space as a rogue planet. We’re safe from Earthfall, so feel free to cross it off your extensive list of apocalypse causes.
Did you enjoy this Nerdoween installment of Spooky Science? Let us know in the comments!
Images: ESA/NASA/SOHO, Geo Beats News, NASA/SDO