What's The Difference Between Comets, Asteroids, Meteoroids, Meteors & Meteorites?

Meteoroids are small fragments broken off from asteroids, ranging from dust grains to less than 3 feet. When they enter Earth's atmosphere, they burn up, creating a bright flash known as a 'shooting star'. Over 48 tons of meteoroids and meteors fall to Earth daily, though most are too small to notice.

All space rocks originated from the early universe, specifically after the Big Bang. They are remnants of materials that didn't form planets but have significantly shaped the solar system and continue to impact it.

Asteroids range in size from about 3 feet to nearly 590 miles in diameter (though Ceres, once the largest, is now a dwarf planet). They are hard to track and can be composed of various materials. Despite their individual danger, the combined mass of all known asteroids is less than our moon, and Earth is largely protected by the gravitational forces of Mars and Jupiter.

When meteoroids enter Earth's atmosphere, they become meteors. If they survive atmospheric entry and hit the ground, they are then called meteorites. Meteorites are highly valuable to scientists as they provide clues about the early universe, and intact specimens are rare and can be very expensive.

Comets are distinct from other space rocks, being primarily composed of ice, water, and dust rather than solid rock. They have direct orbits around the sun, and as they approach it, their ice melts and gasses expand to form a luminous 'coma' or tail, which can be thousands of miles long and visible from Earth. They originate from the far reaches of the solar system, like the Kuiper Belt and Oort Cloud, protecting them from burning up entirely near the sun.

Comets are generally not a threat to Earth due to their distant orbits. While meteoroids, meteors, and meteorites can cause localized damage or harm individuals, asteroids are the primary concern for planetary destruction. An asteroid is believed to have caused the extinction of the dinosaurs, and agencies like NASA actively monitor for potential asteroid impacts. Near misses, like one in Russia, demonstrate the potential for widespread damage from even relatively small asteroids.