So what exactly is the difference between the three? How can someone looking through a telescope know what they're looking at? Read below to find out the difference between all 3 and what exactly they are.
Asteroids
Asteroids are rocky or metallic objects in the Solar System varying in size, Ceres being the largest known asteroid at 933 kilometers (580 miles) across. They range in all sizes with some of the smallest ones being very small (only tens of meters in size). Most of the asteroids in our Solar System orbit our Sun between Mars and Jupiter in what's called the Asteroid Belt. There are also Trojan asteroids which share an orbit with Jupiter, but stay 60 degrees ahead or behind Jupiter. Then there are also Near-Earth asteroids which are Earth's biggest threat. These asteroids orbit the sun in the vicinity of the rocky terrestrial planets; Mercury, Venus, Earth, Mars.
Asteroids are quite different from one another, and some are composed of lots of loosely held together particles making just a big pile of small rocks compacted together in one giant clump. Some asteroids have their own moon, or satellite companion, and also the rare chance of them having an equal-sized partner. Asteroids are not round and smooth due to collisions and not having enough gravity to reshape themselves into a sphere. One key aspect when looking through a telescope is that asteroids do not have the tail that is associated with comets (read about comets to find out what the tail is).
Image via NASA of asteroid Vesta size comparison to other asteroids.
Comets
Comets are mostly ice and dust that grow a “tail” as they get closer to the sun. Comets have a nucleus which consists of the hard rock/ice. The tail is created when the comet gets close to the sun and the solar energy heats up the ice and vaporizes it. The gases formed create the tail and throw up dust and can even break apart the nucleus. The solar radiation pushes the dust particles away from the comet making a tail that can be many of millions of miles long making comets easier to see with the naked eye. When the gas is stripped of electrons it causes an ion cloud which is a blueish color especially noticeable in photos. Comets being mostly ice eventually die off after many passes by the sun heating up and blowing off debris and cooling down again when getting further away.
Comets can be found in two places in our Solar System; the Oort Cloud and the Kuiper Belt. The Oort Cloud is a spherical halo of comets surrounding the Solar System at around 50,000 Astronomical Units, or AU (Astronomical Units is the distance between the Sun and the Earth). Oort Cloud comets have long orbital periods. The Kuiper Belt however is a ring of these icy comets orbiting out beyond Neptune in an area that is about 30-50 AU away from the Sun.. The Kuiper Belt is a sort of carrier for the short period comets that we see. The Kuiper Belt was first discovered in 1992, which has captured interest of astronomers because they may be the oldest, most pristine materials in the solar system. Astronomers know of a few hundred Kuiper Belt Objects that are very large such as the object Quaoar which is half the size of Pluto. Quaoar is the largest Solar System object discovered since Pluto and it's moon Charon, which indicates that there could be larger objects within the belt to be discovered.
Image via NASA - Comet Family Portrait
Meteors
Meteors are the objects you wish upon on a clear night, the objects with the long bright shiny tail, the Shooting Star. These objects are tiny pieces of inter-planetary dust that burn up as they enter the Earths atmosphere at such high speeds. Meteor showers are what happen when the Earth passes through the orbital path of a comet that left a lot of dust behind. The extremely bright and colorful ones you may see are caused by a larger piece of debris which are often referred to as a fireball. These fireballs are not to be mistaken for a comet though because comets do not streak across the sky. When a piece of a meteor makes it to the Earths surface it is then called a meteorite.
Image via NASA of meteors from the Orionid Meteor Shower
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