{"id":13678,"date":"2022-05-28T19:00:32","date_gmt":"2022-05-28T17:00:32","guid":{"rendered":"https:\/\/www.sciencefocus.com\/?p=118364"},"modified":"2022-05-28T19:20:16","modified_gmt":"2022-05-28T17:20:16","slug":"meteor-asteroid-and-comet-whats-the-difference","status":"publish","type":"rss_feed","link":"https:\/\/c01.purpledshub.com\/bbcsciencefocus\/rss_feed\/meteor-asteroid-and-comet-whats-the-difference\/","title":{"rendered":"Meteor, asteroid and comet: What\u2019s the difference?"},"content":{"rendered":"

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By Holly Spanner\n \t\t<\/p>

Published: Saturday, 28 May 2022 at 12:00 am<\/p>

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We\u2019ve observed space rocks for thousands of years. Iron meteorites have been prized throughout history: who can forget King Tutankhamun\u2019s meteoric iron dagger<\/a>, or the Buddha carved from a meteorite<\/a> that fell 15,000 years ago? Likewise, our history of observing comets is extensive, many of which have had a significant impact on human history and the development of legends (or should that be omens?). Halley\u2019s Comet, of course, was immortalised in the famous Bayeux Tapestry<\/a>, made sometime in the 11th Century.<\/p>\n

But what\u2019s the difference between an asteroid and a comet? Or a meteorite and a meteorid?\u00a0Answers to these questions, as well as a round-up of the different types of space rock, are below.<\/p>\n

If you\u2019re looking for more stargazing tips, be sure to check out our\u00a0astronomy for beginners<\/a>\u00a0guide and our UK\u00a0full Moon calendar<\/a> to make the most of the night sky. For a full roundup of this year\u2019s meteor showers, we\u2019ve got them all listed in our meteor shower calendar<\/a>.<\/p>\n

What\u2019s that space rock?<\/h3>\n

Asteroids:<\/strong> Small, rocky objects, often irregularly shaped, leftover from the formation of the Solar System<\/p>\n

Comets:<\/strong> Large, icy bodies of frozen gases, dust and rock, with a frozen nucleus<\/p>\n

Meteoroid:<\/strong> Fragments and debris from asteroids and comets<\/p>\n

Meteor shower:<\/strong> Multiple meteoroids burning up in the Earth\u2019s atmosphere<\/p>\n

Fireball:<\/strong> An exceptionally bright meteor that can be seen over a wide area<\/p>\n

Meteorite:<\/strong> Meteoroids that survive the journey through the Earth\u2019s atmosphere and fall to the surface<\/p>\n

Dwarf planet:<\/strong> A small spherical (or near-spherical) celestial body in orbit around the Sun, that lacks sufficient mass to clear its neighbourhood of debris<\/p>\n

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Asteroid<\/h2>\n

Asteroids are small, rocky objects that orbit the Sun. Most asteroids are irregularly shaped, although there are a few that are nearly spherical. There are over a million known asteroids, and most can be found in the main asteroid belt between Mars and Jupiter. Asteroids are rocky remnants left over from the early formation of the Solar System.<\/p>\n

When an asteroid shares its orbit with a planet, it\u2019s known as a Trojan asteroid. There are two trojan asteroids for Earth<\/a>, however, both are difficult to see as they are leading the Earth in our orbit around the Sun, and therefore appear on the horizon, close to the Sun at sunrise. Not ideal viewing conditions.<\/p>\n

\nhttps:\/\/media.immediate.co.uk\/volatile\/sites\/4\/2022\/05\/The-asteroid-Bennu-as-taken-by-OSIRIS-REx-c48b132.mp4<\/a><\/video><\/div>\n

Asteroid Bennu (shown in the above video by NASA\u2019s Scientific Visualization Studio) made the news in 2020 when NASA\u2019s OSIRIS-REx mission successfully landed on the asteroid\u2019s surface and collected over 400g worth of samples. It was an impressive achievement, and one which smashed the original target of 60g.<\/p>\n

Bennu is estimated to be around 4.5 billion years old, forming just after the formation of our Solar System. It\u2019s most likely a piece of a much larger carbon-rich asteroid, breaking off around 700 million to 2 billion years ago and making a close approach to Earth every six years.<\/p>\n

But astronomers must be patient for a little while longer as the spacecraft is still on its way back home, due to swing by on 24 September 2023<\/a> to deliver the precious cargo. After that, the spacecraft will head out again, this time to study the near-Earth asteroid Apophis, under a new mission name OSIRIS-APEX<\/a>.<\/p>\n

Comet<\/h2>\n

Comets are the snowballs of the cosmos. These icy bodies of frozen gases, rocks and dust orbit the Sun on highly elliptical paths, often tumbling as they go. When their orbit brings them close to the Sun, they heat up. This causes the solid ice to turn into gas, which is swept into the distinctive comet tail. Arguably the most famous comet is Halley\u2019s Comet, which is due to return to our skies in July 2061.<\/p>\n

\"""\"<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>
Comet 67P\/C-G, known as the \u201crubber duck\u201d taken by Rosetta\u2019s NavCam. It\u2019s a short-period comet originally from the Kuiper belt, with a current orbital period of 6.45 years \u00a9 ESA\/Rosetta\/NAVCAM<\/span><\/figcaption><\/div>\n

Comets are so varied in size, orbit and composition that this has resulted in numerous classifications over the years. However, for argument\u2019s sake, they can be sorted into four broad categories:<\/p>\n