So – You’re Still Interested in Astronomy?4 min read

Hello again.

Last time we looked at the amazing satellites surrounding Pluto. This time around we’ll take a look at the moons of the rest of the dwarf planets in our Solar System, along with the parent bodies themselves. As you see, they might be small, but that doesn’t mean they’re not interesting.

1. So – which particular places will we be looking at?

Today we’ll take a look at Ceres, Orcus, Quaoar, , Makemake, Haumea, Sedna and Eris.

2. Ceres



At 2,326 km (1445 miles) in diameter, Ceres is the largest object to be found within the main Asteroid Belt. In fact, Ceres possesses a third of the mass of the entire belt and is the largest of the minor planets within the orbit of Neptune.
The interesting thing about Ceres is that she has an icy mantle around a rocky core, and it is thought she may possess an internal ocean of liquid water.

3. Orcus

Orcus is a Kuiper Belt Object (KBO). Discovered of February 17th 2004, she is classified as a Plutino, in that she orbits like Pluto does – in resonance with Neptune, and will encircle the sun twice to every three orbits of Neptune. Interestingly, she is always in opposite phase to Pluto herself.

4. Anything else?

Despite her small size, Orcus possesses a moon called Vanth, which orbits her parent body in a tight circle once every ten days. So far, studies have revealed she appears to be tidally locked with Orcus.

5. Quaoar

Quaoar is a Kuiper Belt Object roughly half the size of Pluto. She was discovered on June 4th 2002 and is named after the Tongan creator god. She is the first Trans Neptunian body to be measured by the Hubble Space Telescope, and is known to form part of a binary system following a collision with another, larger KBO body.
Evidence of cryovolcanism exists on her surface, most likely from the decay of radioactive elements beneath the surface.
Quaoar has a single moon, called Weywot

6. Makemake



Makemake is the largest Kuiper Belt Object possessing a diameter approximately two thirds of Pluto, and she has no known satellites. Makemake is what is termed a classical KBO, in that she is far enough from Neptune not to be influenced by its gravitational mass.
Of interest is the fact that this minor planet has an extremely low surface temperature (243°C) only 30K which suggests she is covered in methane, ethane and nitrogen.

7. Haumea

Haumea is a Plutoid with a third of the mass of Pluto. She has an unusual elongated shape unique to the minor planets which scientists think is due to what is called a giant collision. (A major event in that area of space that destroyed a number of large bodies, creating a collisional family) Haumea is the largest result of that collision.
Haumea has two satellites. Hi’iaka – the larger outer moon, and Namaka, the smaller inner sister.

8. Sedna



Sedna is a large minor planet that lies in the outer reaches of the solar system about three times the distance of Neptune from the Sun.
Like all other trans-Neptunian objects, she is composed of water, methane, nitrogen and tholins.
Fact: Sedna currently lies in what is called the Scattered Disc, a group of objects sent into a highly elongated orbit by the gravitational influence of Neptune, and she possesses one of the reddest surfaces of any other body in the solar system.

9. Eris

With a diameter of 2400km (1492 miles) Eris is the most massive and second largest dwarf planet and ninth most massive body known to orbit the sun. She lies more than three times further away that Pluto and for a while, was thought to be an actual planet. Eris has two moons, Dysonomi, and recently discovered Gabrielle.

FACT: Eris is the largest known body in the solar system not to have been visited by a spacecraft.

10. And finally

Sedna is due to reach perihelion in 2075-76 providing an opportunity of study unavailable for the next 12,000 years! A planned mission to visit Eris on either April 2032 or April 2044 will take 24 years to get there.

Weird to think it’ll take longer to get there than some of you reading this have been alive, eh?

But that’s what makes our small Solar System so fascinating.


So there we go. That’s our brief look at the wonderful world of the dwarf planets and their Moons.
Next time, we’ll move on to take a closer look at the Main Asteroid Belt and see what we can find there.

Stay tuned,

I can’t wait to see you then…

Andrew Weston
Andrew Weston

Andrew P. Weston is Royal Marine and Police veteran from the UK who now lives on the beautiful Greek island of Kos with his wife, Annette, and their growing family of rescue cats. An astronomy and law graduate, he is the creator of the international number one bestseller, The IX, and also has the privilege of being a member of the Science Fiction and Fantasy Writers of America and the British Fantasy Society. When not writing, Andrew devotes some of his spare time to assisting NASA with one of their remote research projects, and writes educational articles for and Amazing Stories. He also enjoys Greek dancing and language lessons, being told what to do by his wife, and drinking Earl Grey Tea. If you would like to find out more, visit his blog or website at:

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