There are many moons across our solar system, some planets hosting much more than others, but that doesn’t mean every planet has them in orbit. So that begs the question; which planets do not have them? Let’s find out, and why, shall we?
So, which planets do not have moons? The only planets in our solar system without moons are Mercury and Venus. Still, there’s a long history with all of our planets that explains why or why not they have moons surrounding them.
Although plenty is known about our own solar system, experts are also searching far and wide for exomoons that exist far and wide among the never-ending list of exoplanets.
So this is definately a field with a lot of interest, and where new developments can unfold.
That being said, a lot is already known about the moons within our own solar system.
So let’s delve into where they are perhaps, missing.
What Planets Do Not Have Moons?
Mercury and Venus are the only moons that don’t boast any moons in their orbit.
You also want to consider that research is still being done to determine how many exoplanets have exomoons, but there’s a lot to discover before experts will be able to confirm this.
Nevertheless, let’s get into the details on the few planets in our solar system that don’t have any moons and why that is.
Mercury
Due to a variety of factors, moons wouldn’t be able to remain in a stable orbit around Mercury.
From being too close to our massive sun, and the overall size of the planet, it just isn’t scientifically feasible.
Moreover, because it wouldn’t remain in a stable orbit, any moon around Mercury would undoubtedly be swallowed up by the sun as the planet is relatively close to the star.
Regardless of each individual reason, Mercury doesn’t have any moons because of complications with gravitational interactions and orbital dynamics.
When you also take into account that Mercury has much weaker gravity than other planets in the solar system, it makes sense why a celestial object such as a moon wouldn’t be able to sustain itself in the planet’s orbit.
In the same vein, at some point in history, it’s possible that Mercury could have had a moon at some point, but it’s unlikely it existed for very long.
It takes a special set of factors for a moon to thrive in orbit for the long run, and Mercury simply doesn’t have the qualities that are needed.
It does make for plenty of curiosity as to why some planets have moons and others don’t, but it’s doubtful that Mercury will ever have a sustaining moon throughout its existence.
Then again, the universe has proven us wrong many times, and its existence is far greater than our time here on Earth.
A moon could be a possibility for the planet but based on past and present historical data, scientists don’t seem to think it’s very likely.
Overall, the sun is one of the most prominent reasons for Mercury not having a moon, as its gravitational force is far greater than Mercury’s.
his alone would pull any moon away from the planet’s orbit. From another perspective, if a moon did try to reside in Mercury’s orbit, it would have issues with stability, and it’s probable that the moon would eventually fall into the planet itself.
Another factor you can take into account is that Mercury’s rotation is fairly slow in comparison to other planets.
It takes the planet over 1,400 hours to complete a rotation that equals 59 Earth days, and this slow rotation causes substantial instability for any object in Mercury’s orbit.
There are quite a few issues that come with Mercury trying to hold a moon in its orbit, but it all comes down to the significant tidal gravities that would ultimately destroy the moon no matter what.
Venus
The other planet in our solar system that doesn’t boast any moons, Venus, comes with a few similar complications to Mercury, but it also has many unique qualities of its own.
For starters, Venus has a very small space for which its gravitational pull has any effect, and this is due to its distance from the sun.
Of course, its gravitational pull comes with some strength, but it is not enough to successfully hold a moon in orbit.
Because of its unique position in our solar system, most space debris simply hasn’t been able to enter the planet’s orbit.
Even though moons come in all shapes and sizes, the planet isn’t built to sustain such an object. Like Mercury, there’s always the possibility that Venus could have had a moon at some point in history.
It can be assumed that space debris came into contact with Venus throughout history, but it either crashed into the planet or simply escaped the planet’s gravitational pull.
Venus and Earth are similar in regard to composition and size, but Earth has the necessary features to tidal lock its moon in orbit.
The distance between a planet and the sun also plays a significant role in whether or not a planet can host objects in its orbit.
Earth is known to be in a pretty lucky position that allows it to be habitable and carry a balance that allows the moon to remain in place. The closer a planet is to the sun, the more it will feel the effects of the sun’s massive gravitational pull.
Considering Venus is much closer to the sun, it only has a small gravitational band that would allow a moon to remain in orbit, and it’s clear that this force isn’t strong enough to hold a moon in place for any length of time.
From our small perspective, it looks like nothing ever changes in our solar system, but in reality, it could look vastly different long after we’re gone.
Celestial events could occur that change many of the properties we understand today, and maybe one day, Venus or Mercury could make another attempt at hosting a moon of their own.
Outer space has plenty of debris passing by our planets all the time.
We can’t track every piece, but this is how many planets ended up with a moon in the first place.
Unfortunately, Venus is in a unique position that doesn’t allow debris to remain in orbit, and it’s pretty unlikely that this will change if it remains at the same distance from the sun.
It’s understood that the sun boasts over 99% of the whole mass of our galaxy, so it’s easy to see why its mass and gravitational pull overpower comparably small planets such as Venus or Mercury.
Why Do Some Planets Not Have Moons?
A vast number of properties come into play for planets that don’t host any moons, but it’s all primarily due to the sheer force and size of the sun.
Every planet in our solar system has moons outside of Mercury and Venus, and this is because they are the closest to the sun.
It’s more than just the sun’s influence, as their size, position, and individual gravitational pulls all have an effect on space debris that passes by.
It’s unlikely that Mercury or Venus will ever have any celestial object in their orbit during our lifetime, but there’s always the possibility, considering the vast possibilities our universe is known for.
This has also led experts to look into planets outside our solar system.
Specifically focusing on how their properties compare to those with exomoons and those that don’t. We don’t have nearly as much research available on this topic, but we have discovered that some planets have different kinds of moons.
Every Moon’s Story Is Unique
Nevertheless, whether or not a planet has a moon takes numerous factors into account.
Whether they’re close to a star, or other planets, including their own size, composition, and gravitational pull, all play a part in a planet’s ability to host a moon.
You’ll also notice that planets that have multiple moons carry them in orbit at varying distances and locations. It’s another aspect that shows a unique set of properties is needed for a moon to form or reside in a planet’s orbit.
Those who don’t already have their own moons will likely remain that way for a very long time.
This also has created the need for research on how a moon could potentially affect a planet that didn’t have one before, as Earth’s moon is clearly a vital aspect of our life on the planet.
Aside from what’s required for a moon to successfully remain in orbit around planets such as Mercury or Venus, it has led experts to wonder about the pros and cons of the planet’s hosting their own moon.
What Does It Mean For Planets With No Moons?
The first idea that comes to mind is that if a moon tried to remain in either Mercury is Venus’s orbit, it could eventually cause catastrophic damage to the planet.
This event could go a few different ways depending on the size of the moon, as it could either drift off into the sun or be pulled into the planet.
Many experts assume that the planets in our solar system that don’t have moons will remain as they are, but if one tries to enter their orbit, there’s a potential for disaster.
Dangers of Cause and Effect
If they came in contact with space debris that was large enough to eventually form a moon, which ended up crashing into the planet, it could cause a domino effect of events.
Not only will it cause substantial damage to the planet, but if large enough, it could affect its place in our solar system and its orbit around the sun.
From the opposite spectrum, if they had a moon pull away from its orbit, there wouldn’t be much of a change to its current status, as it would soon return to the normal existence we’re familiar with right now.
You can’t really attach the presence of a moon to any potential of habitable life, as both planets would remain in their relatively barren state.
Changes In Temperature
Now, regarding temperature, this could definitely be affected if a moon was in either of the planet’s orbits.
A change like this would surely cause some fluctuations on the surface, and it’s possible for a sizeable moon to even block out the sun on rare occasions.
This, of course, would be an extremely rare happening in our lifetime, but a moon’s effect on either planet wouldn’t really cause much change to our life here on Earth.
Potential For Disaster
Let’s say a massive moon tried to come in contact with either Mercury or Venus; it’s possible that the potential damage could be so catastrophic that it would lead to the planet’s eventual end.
This would require a very large moon, but it doesn’t take much for a celestial collision to entirely ruin a planet’s life cycle.
We talk about it on Earth all the time, that life as we know it would essentially end in many ways if our moon fell into the planet.
The same would happen to Mercury or Venus as they’re in a much more vulnerable position with being so near to the sun, considering they simply aren’t built to hold such an object in orbit in the first place.
Potential For A Moon
If the planet’s tried to hold a moon, you can bet that scientists would immediately start to look into the potential outcomes, as nothing in our universe is immune to disaster.
Thankfully, this isn’t an event that we have to worry about too much, but there’s always a chance that if the right events align, Mercury or Venus could attempt to hold a moon in orbit.
Experts would be sitting at the edge of their seats, wondering what would happen next.
It should also be noted that if a moon large enough fell into Mercury or Venus, a ton of debris would go flying into outer space, and it’s possible some of that debris could head toward Earth.
Nevertheless, scientists are well aware of the possibilities, and we can only hope the planets remain safely in place without facing sizeable space debris.
Related Guides:
- Why Does Saturn Have So Many Moons? [& What Are They Like?]
- Why Does Jupiter Have So Many Moons? [This Is Fascinating!]
Hey, my name is Chris. I’m a passionate and seasoned astronomer who loves nothing more than observing the night sky. I also love researching, learning, and writing all things Space and the Universe. I created Astronomy Scope to share my knowledge, experience, suggestions, and recommendations of what I have learned along the way while helping anyone to get into and maximize their enjoyment of the hobby.