While Comet ISON’s eagerly anticipated encounter with the sun won’t even happen until November, it seems likely the fireball is already prepping a special encore performance for stargazers here on Earth.
In January, the US space agency’s Swift spacecraft observed the comet ISON while it was still near the orbit of Jupiter. Even then, it had already become extremely active, with more than 112,000 pounds of dust being ejected from the comet’s nucleus each minute.
Now NASA scientists are reporting some of that dust could wind up here on Earth following it’s close-encounter with our sun. That discovery comes as a result of computer modeling efforts led by Paul Wiegert of the University of Western Ontario (UWO), who has been tracking Comet ISON and discovered the potential meteor shower that could result.
“For several days around January 12, 2014, Earth will pass through a stream of fine-grained debris from Comet ISON. The resulting shower could have some interesting properties,” Wiegert said. “Instead of burning up in a flash of light, they will drift gently down to the Earth below.”
According to his computer models, Comet ISON’s debris stream is filled with extremely minute grains of dust which are only a few microns wide and will be pushed towards the Earth due to the sun’s gentle radiation pressure. They will be traveling at a speed of 125,000 mph, Wiegert said, and because of their tiny size, our planet’s upper atmosphere will cause them to slow down to a stop.
Unfortunately, the bad news is it is quite unlikely anyone will be able to notice. The comet dust would be difficult to see and would be traveling very slowly, meaning it could take months or even years to settle out of the high atmosphere, NASA said. However, it could produce noctilucent clouds (NLCs) – icy clouds that have a bluish glow when they float more than 48 miles above the Earth’s poles.
“Recent data from NASA’s AIM spacecraft suggests that NLCs are seeded by space dust. Tiny meteoroids act as nucleating points where water molecules gather; the resulting ice crystals assemble into clouds at the edge of space itself,” the space agency added. “This is still speculative, but Comet ISON could provide the seeds for a noctilucent display. Electric-blue ripples over Earth’s polar regions might be the only visible sign that a shower is underway.”
Furthermore, Wiegert said the dust shower would hit our planet from two different directions at the same time. As the planet passes through the debris stream, one swarm of comet dust will be following Comet ISON into the sun. The second will be moving in the opposite direction as it is pushed away from the sun due to solar radiation pressure. This kind of “double whammy” is “unprecedented,” the Canadian astronomer added.
According to Bill Cooke, lead scientist at NASA’s Meteoroid Environment Office (MEO), there is little to no danger to spacecraft and probes orbiting around the Earth. “These particles are just too small to penetrate the walls of our satellites,” he said, “and they don’t stand a chance against the heavy shielding of the ISS.”
