Article written by: Ciara, from Ciara’s Journey Blog

It’s an umbrella term for Comets, Asteroids, Meteoroids, Meteors, Meteorites and Bolides.  It’s anything that is in our Solar System and that isn’t a planet or a satellite!

In this blog post I have explored what each of these things are – from responsible sources like ESA and NASA. 


Comets are frozen snowballs of gas, rock and dust that orbit the Sun.  When a comets orbit brings it closer to the Sun it heats up and throws out dust and gases into a giant glowing head sometimes larger than some planets.

This close-up look at Comet ISON (C/2012 S1), from NASA’s Hubble Space Telescope. This image was captured on 10 April 2013, when the comet was at a distance of 386 million miles (slightly further than Jupiter) from the Sun. This image was taken in visible light. The blue false colour waadded to bring out details in the comet’s structure. (Image credit: NASA, ESA, J.-Y. Li (Planetary Science Institute), and the Hubble Comet ISON Imaging Science Team)

The gases and dust make a tail form that stretches away from the Sun for millions of miles.  Well, comets actually have two tails, one tail is a trail of dust that has drifted off the surface and the other tail is gases that have boiled off the nucleus.  Interesting fact: As of the 13th of July 2019, the current known count of comets is 6,619!

Some Scientists think that comets provided the water for Earths oceans and maybe even brought the molecules from which life developed.


Asteroids are rocky, airless leftovers from the early formation of our solar system (4.6 Billion years ago). 

Some were formed from piles of rubble; some were rocks lucky enough to escape a planet intact.  I remember last January (2019) watching pictures of Arrokoth (formerly known as Ultima Thule) being sent back to us.  This was two rocks that had crashed into one another and continued traveling afterwards.

In a fitting tribute to the farthest flyby ever conducted by spacecraft, the Kuiper Belt object 2014 MU69 has been officially named Arrokoth, a Native American term meaning “sky” in the Powhatan/Algonquian language. Image credit: NASA

The total count of asteroids as of March 2019 is 840,493.  But of course, by the time this blog goes out the number would have probably doubled. Science (and so space) is constantly evolving.

Asteroid Belt

You can find the Asteroid belt between the orbits of Mars and Jupiter and it’s filled with asteroids of many sizes. 

However, there are two myths we need to debunk. First up. You may have thought the Asteroid Belt was thick and crowded – but, it’s almost completely empty.  Plenty of spacecraft have flown through the belt without meeting any asteroids at all (at this time).  Something interesting is that the chance of meeting an asteroid traveling through the belt has been estimated to be 1 in a billion.

Also, scientists have confirmed that that the belt is NOT the remains of old planets as previously thought – it only contains a fraction of a fraction of a planets mass!

As of this month (January 2020), Jupiter is currently sending a lot more asteroids in the direction of Earth.  We usually look to Jupiter to protect Earth from incoming comets and asteroids but this time its throwing them at us! 

To our knowledge the asteroids are either missing us entirely or are very small and will probably burn up and break up if one enters our atmosphere.


These are objects in space that can range in size from dust grains to small asteroids.   Meteoroids are chunks of iron or stone that travel around in a various orbits or speeds and can reach up to 42 kilometres per second.

When they enter the Earth’s atmosphere at high speeds, friction between the meteoroid and gases in our atmosphere heat it up and makes it glow.  It then becomes visible to the naked eye.  We also know these as Fireballs, Shooting Stars or Meteors.


When a meteoroid survives a trip through the atmosphere and hits the ground it’s called a meteorite.  When it hits the ground, it displaces material causing an impact crater


A Bolide or Fireball is an exceptionally bright meteor that often burns up in the atmosphere.  One of the most well known Bolides is the Chelyabinsk Event of Russia in 2013.

This photograph shows the meteor streaking through the sky above Chelyabinsk, Russia, on Feb. 15, 2013 Credit: NASA / M. Ahmetvaleev

I hope you have enjoyed this blog about Small Solar System Orbiters. If you would like to learn more about Ciara’s Journey (my blog) please click HERE.

Sources used: NASA and Gizmodo

1 Comment

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