![]() Where Do Comets Come From?Īs theorized by astronomer Gerard Kuiper in 1951, a disc-like belt of icy bodies exists beyond Neptune, where a population of dark comets orbits the Sun in the realm of Pluto. Comets may have brought water and organic compounds, the building blocks of life, to the early Earth and other parts of the solar system. They have been referred to as "dirty snowballs." They may yield important clues about the formation of our solar system. We now know that comets are leftovers from the dawn of our solar system around 4.6 billion years ago, and consist mostly of ice coated with dark organic material. These historic comet annals have proven to be a valuable resource for later astronomers. Chinese astronomers kept extensive records for centuries, including illustrations of characteristic types of comet tails, times of cometary appearances and disappearances, and celestial positions. But now we have more of an understanding about how an ocean impact may go down, we might be able to slightly nudge it toward a new target that will produce less collateral damage, like the middle of the ocean.In the distant past, people were both awed and alarmed by comets, perceiving them as long-haired stars that appeared in the sky unannounced and unpredictably. If you find an asteroid in this size range is on a collision course with Earth, and you can't deflect it from hitting the Earth's surface, you might be able to deflect it into the middle of the ocean," he said.Īlthough NASA and other agencies are working to identify and track asteroids that pose a significant threat to Earth, we could be blind-sided and have little time to prepare a mission to knock the asteroid off course. Gisler's research adds another layer of understanding of how an asteroid impact would affect Earth and, for asteroids of 300 meters wide or less, we could use an ocean impact as a strategy to limit global damage. RELATED: Huge Tsunamis May Have Ravaged Ancient Mars Intense shock waves and violent winds will also wreak havoc on the surface, so the further the impact is from any populated coastal regions, the better. Water vapor is a potent greenhouse gas, so the injection of vapor into the stratosphere could linger for months or years, altering global climates. In addition, a significant fraction of the kinetic energy of the impacting asteroid will go into vaporizing huge quantities of water, according to the team's award-winning video explaining the research findings. "That's awfully high! But unless it's very close to a shore, it's not going to be very dangerous." According to the model, a jet of water would also protrude from the ocean's surface by a few kilometers, producing rim waves surrounding the transient water crater reaching 400 meters in height. "They're spectacular to be sure they would produce splashes that go up tens of kilometers ," he added. Tsunamis aren't very dispersive and therefore don't lose energy as they travel through the ocean basin, hitting coastlines hundreds or maybe thousands of kilometers away, often with devastating results.īut that's not to say an asteroid impact in the middle of an ocean wouldn't be dramatic. These shifts cause a huge movement in a massive column of water, from the seabed to the surface, that can create wavelengths of a hundred kilometers or more, said Gisler, which is many times longer than the depth of the ocean (of a few kilometers). ![]() Tsunamis occur when there's large scale shifts of mass in the seabed, such during a submarine earthquake or landslide. ![]() These dispersive waves in an ocean will be very localized and won't have the energy that a tsunami does. In other words, they lose their energy very quickly. Sure, the energy of the rock hitting the water will produce waves, but the ripples are very dispersive. ![]() He likens an asteroid ocean impact to throwing a rock into a pond. "An asteroid impact is a point source and it only affects the immediate region around the impact point and moreover, to create a tsunami, you need something that disturbs the entire water column," said Gisler. Never before has an impact scenario like this been studied in such detail and the simulation revealed that Gisler's original instincts had merit: devastating post-impact tsunamis we see in the movies are as fictional as the science fiction plot lines they are a part of. Gisler is determined to better understand the realities of a massive impact in the ocean and presented his team's findings at the American Geophysical Union's Fall Meeting in San Francisco last week, showcasing the dramatic 3-D modeling results of an ocean-impacting asteroid. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |