Dwarf planets are not as small as one might think – in fact, they are very much like our own planet. And, just like the Earth, they orbit the Sun or its equivalent – that is another star. Sometimes, they can have satellites, like the Earth has its Moon, or other bodies in their orbital vicinity. We have identified multiple dwarf planets so far, and it seems more of them might exist, maybe even in our own system. But how is a minor planet different from a fully-fledged one? Spoiler alert: it’s not just about the size.
Since 2006, heated debates have surrounded Pluto’s classification, which as you might have heard, lost its fully-fledged status. Today, it is officially a minor planet not the last full-scale object in our system. But let’s dive deeper into the subject of dwarf planets to learn top facts about these small far-away worlds.
What makes a planet a dwarf?
International Astronomical Union set planetary science definitions and determined that planets:
- orbit a star;
- have a spherical shape;
- can clear their orbital paths with their own gravity force.
Any object that does not meet all three criteria is considered a minor or dwarf planet. In the dwarf planet vs planet battle, the most common difference is the size, of course – the bigger the body, the more gravity it has. In turn, this means it is strong enough to pull other large bodies, like asteroids, into its orbit.
Pluto, for example, cannot do this – which is why it was recently demoted. Still, it is a massive object – our system does not have a bigger dwarf than Pluto.
What are dwarf planets made of?
Dwarf planets are made of ice or rocks, depending on how far away they are from the Sun. However, their composition is poorly studied and can vary greatly. Some may be icy, rocky, and may even harbuor some liquid water. As far as we know it today, our Pluto is mostly ice and rock, but no liquid water.
Eris, the largest dwarf planet after Pluto, is another curious case study. Its entire surface is covered in icy nitrogen. Ceres, one more large dwarf between Mars and Jupiter, most likely features a solid core and a water ice mantle. In fact, it could be 25% water, which means it might have more water than Earth. There is a theory that its crust may also have salt deposits, but we will need to study it more closely before we can jump to any conclusions.
Do dwarf planets have life?
Dwarf planets in our solar system do not have any life – at least as far as we know. But according to Orbital Today, they are still a mystery for humanity. Ceres, it seems, has traces of water, which may mean it might have life in the form of small microbes like bacteria. But these life forms, assuming they exist, are like nothing we know of Earth. For example, Haumea, one more minor planet in our system, is too cold and doesn’t seem to offer habitable conditions. The same goes for Makemake and Eris. At the same time, new research says asteroid impacts on Ceres influenced the presence of organic aliphatic molecules here. In the Milky Way, thousands of dwarf planets are expected to exist, but only 6 of them have been confirmed so far.
Facts about dwarf planets: What Else Do We Know
Now that we have determined some basic facts about dwarf composition, let’s see what other facts we can learn today:
- Ceres is the closest dwarf planet to Earth, situated 264 km from our planet. A day on Ceres lasts 9 Earth hours, whereas a year lasts 4.5 Earth years.
- You can’t see any of these objects with the naked eye – only using advanced optics and professional telescopes.
- Because of the huge distance from their star, dwarves have very low temperatures. For instance, Pluto’s average temperature is -240 °C.
- Since dwarves are located at a great distance from the Sun, it takes them many years to complete a full revolution around its star – that is, ‘years’ in our terrestrial terms.
How many dwarf planets are there & their location
So, where are the dwarf planets located? And do we really have a lot of them? In our system, five have been confirmed so far. All of them are also called trans-Neptunian because they are situated beyond Neptune’s orbit. However, Ceres is once again the exception – it is the only one located between Jupiter and Mars. Unlike this one body, others are called “plutoids.” “Ice dwarfs” is another name for these bodies since they are usually frozen worlds.
Still, our science does not stand still, and as our probes and telescopes advance, we are likely to discover more minor planets as we keep exploring our galaxy.
