More than 1 million asteroids left over from the early formation of our solar system orbit the sun in the main asteroid belt between Mars and Jupiter. Tens of thousands more orbit outside that belt.
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Cometary orbits are known to exhibit accelerations independent of gravity that result from forces related to the release of gases. Dark comets exhibit this behavior but lack visible clouds of frozen material that have turned into a gas—the coma the comets display—indicating minor quantities of escaping subsurface ice.
These objects range in size from a grain of sand to a pebble and originate from the breaking apart of rocky asteroids due to collisions or from the debris of icy comets' tails. As they enter Earth's atmosphere, they burn up and create streaks in the sky called meteor showers.
Established in 2016, the Planetary Defense Coordination Office characterizes and tracks asteroids and comets passing within 30 million miles of Earth. Over 39,000 near-Earth asteroids have been discovered, although estimates suggest that about 14,000 more such objects remain to be found.
A main-belt asteroid previously labeled 274301 was renamed "Wikipedia" by the Committee for Small Body Nomenclature. First observed in 2008 by astronomers at the Andrushivka Astronomical Observatory, the asteroid was renamed based on a suggestion from a member of the Wikimedia Foundation in Ukraine.
While NASA states that no known asteroid currently threatens Earth, past impacts demonstrate that the risk is real. The agency has tested deflection technology to alter an asteroid’s path, as this visualization imagines a worst-case collision scenario.
Tens of thousands of asteroids are in orbit in our solar system, and only a fraction come close enough to concern humanity. This simulator allows you to see the big picture scenarios of an asteroid impact, strategies to mitigate its destruction, and how Earth could defend itself.
This 3D solar system visualization displays the positions of known asteroids, comets, and spacecraft involved in asteroid studies. Major asteroids include additional details, including orbital trajectories and discovery dates.
Asteroids contributed to planet formation and carried water from the solar system's outer reaches toward the center. They were also early providers of the necessary elements and conditions for life to evolve on Earth.
While looking for a planet between Mars and Jupiter to coincide with an apparent mathematical pattern in the distances of known planets from the sun, a group calling themselves the "Celestial Police" discovered multiple objects that fell into a new classification.
Even a 1-kilometer-wide asteroid can trigger earthquakes and tsunamis on impact with oceans. The overwhelming majority of asteroids that reach Earth are much smaller and burn up in the atmosphere before reaching the ground.
Since our ancient human relatives began using stone tools to perform tasks, humans have harnessed scientific knowledge and new technologies to expand the boundaries of our understanding of the natural world. From quantum computing and microplastics to artificial intelligence and memory, explore these topics and more with our concise yet informative overviews and expert-curated resources.