Near-Earth objects are comets or asteroids in orbits that allow them to enter Earth's neighborhood.
In its journey through space, Earth is bombarded by a hailstorm of comets, meteors and asteroids.
While certainly spectacular and ethereal in appearance, comets are essentially "big, dirty snowballs" flying through space.
But there is reason to believe that comets are what the Kuiper belt mostly consists of.
That would help to explain a puzzling anomaly about comets: they fall into two classes.
But there are about 1000 so-called short-period comets, whose orbits take less than 200 years.
Lights might dim slowly from the edges or shapes will unexpectedly dart across the surface like comets.
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Now, two comets are expected to put on a naked-eye spectacle for sky watchers in the Northern Hemisphere.
One big mystery is that comets become active long before they should if their content was just water.
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Comets are made up of water, ice, dust and other elements and minerals, all loosely packed together, Battams said.
Most asteroids are made of rock, while comets can be a mixture of rock, organic molecules and frozen gases.
But organic molecules could be manufactured on Mars from nonlife sources, or they could come from meteorites and comets.
Subsequent missions will analyse the solar wind, three comets and the planet Mercury.
The data are the orbits of comets that are likely to have been first-time visitors to the inner solar system.
This makes them up to 20 times bigger than those more familiar denizens of the deepest solar system, the comets.
Short-period comets have their short periods precisely because of their interactions with closer-by planets, which are already known to astronomers.
Meteor showers are generated when Earth plows through streams of debris shed by comets on their path around the sun.
But comets were really only unpredictable to ancient peoples, who lacked a knowledge of the full extent of the solar system.
The collision will help scientists learn more about comets, and it will also make for some stratospheric fireworks on Independence Day.
Some astronomers seemed to think that he and his colleagues had been too selective about the sample of comets they studied.
So the argument that some of the dots are comets depends on showing that there are more dots than chance should allow.
Little comets of white lights arcing over the city's narrow streets made Vienna feel more like Christmas than any sleigh-and-reindeer-infested lawn ever could.
But, according to Dr Matese, once you start including comets with shorter orbital periods, you lose sight of the wood for the trees.
The nebula itself is named Barnard 3, after its discoverer, Edward Barnard, who discovered over a dozen comets and over 300 nebula.
Those periods, though, are measurable only because they are short enough for astronomers to have seen the comets in question more than once.
Large sun-grazing comets could bring on the sort of global electronics meltdown usually associated with electromagnetic pulse weapons or a full-scale nuclear exchange.
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Scientists speculate that the fragmentation took place either during the process of capture or possibly after capture due to collisions with Jupiter-crossing comets.
After looking at the orbits of almost 300 long-period comets, they have concluded that too many are coming from particular parts of the sky.
Near-Earth objects are asteroids or comets, believed to be remnants from the formation of the planets, whose orbits brings them close to the Earth.
There's an important distinction between these two types of objects: Comets are mostly water, ice and dust, while asteroids are mostly rock or metal.
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