Jupiter is old. Like 4.5 billion years old. It started as a swirling disk of gas and dust that formed into a pretty big planetary core. With time, Jupiter’s core grew, attracting more and more rock, ice and metal. But Jupiter wasn’t going to become a rocky planet. No. It had an enormous appetite for gas.
Jupiter’s powerful gravitational pull drew in massive amounts of hydrogen and helium that shaped it into the majestic gas giant we see today.
What if, instead of gas, Jupiter kept pulling in more rocky materials until it became the most massive terrestrial world in the Solar System?
This world would be four times heavier than its gas giant form. And keep in mind, the gas giant Jupiter is already about twice as massive as all the other planets in the Solar System combined.
With this enormous mass would come unimaginably strong gravity. Rocky Jupiter’s gravitational pull would now be four times more powerful than it was before. That’s 10 times stronger than gravity that you and I live with here on Earth.
Yeah, you wouldn’t be able to walk on this rocky Jupiter. Your body would experience a gravitational pull so extreme that it would break your bones. Your heart would beat out of your chest, working so hard to pump your blood. And as your blood pooled in your lower body, you’d feel dizzy and lightheaded.
Well, you might not want to walk on this Jupiter anyway. The rocky king of the Solar System would now attract even more moons and asteroids. And some of them would be on a collision course with the rocky giant.
But what would its surface be like anyway? Apart from the constant asteroid collisions, it could be a pretty nice place to visit. If you could walk there, of course.
Rocky Jupiter would still lie outside the Solar System’s habitable zone. But this doesn’t mean it would be a frigid world. Jupiter is gigantic. And rocky Jupiter could retain a lot of internal heat from when it formed. So even though it’s so much further from the Sun than Earth, rocky Jupiter could have surface temperatures similar to our planet.
It might even have hot oceans. Terrestrial Jupiter’s gravity might cause the planet to have a very thick atmosphere. And worlds with thick atmospheres have high atmospheric pressure. That means that the boiling point of water on this rocky giant would be higher than it is on Earth. And the oceans could be as hot as 200 °C (390 °F) and still remain liquid. Yeah, I wouldn’t recommend swimming there.
Even if you could somehow walk on this world, you wouldn’t want to breathe on it. Gas giant Jupiter’s atmosphere is mostly hydrogen and helium. So if the rocky Jupiter’s atmosphere was also made of hydrogen and helium, it wouldn’t be breathable.
Then, there would be lightning storms. Yeah, Jupiter already has massive storms in its clouds. And rocky Jupiter would be no different. If this planet also had active volcanoes spewing ash and lava, these would make the lightning storms even more intense.
Volcanoes could be good news for this rocky world, though. The gases they release might change the atmosphere of the rocky Jupiter and make it habitable. If not for you, then for some other lifeforms.
And those other lifeforms could be terrifying. They might be bigger and stronger than dinosaurs just to withstand Jupiter’s enormous gravity.
Or they could be tiny microbes living under rocky Jupiter’s surface. But obviously, that’s a lot less exciting.
The thing is, Jupiter’s increased gravity would push our planet out of its stable orbit. And that would dramatically change our climate. Earth could be pushed closer to the Sun, turning this place into a hot, hellish world. Or we could be driven further from the Sun and freeze over. Either way, this would be bad news for you.
And Earth wouldn’t be the only planet pushed out of its orbit. Everything in the Solar System would plunge into chaos. Planets and moons would be knocked off-course, some of them colliding with each other. Things would get messy. You could only hope that nothing would crash into Earth.
