Something we do NOT want to happen

Rogue planets. Cold, boring, and dead. Rogue planets (also called an interstellar planet, nomad planet, free-floating planet, unbound planet, orphan planet, wandering planet, starless planet, or sunless planet) are planets without a sun to orbit. And it’s not impossible that Earth could become one of those too. What if a star came and hit our Solar System?

Most stars are moving through the galaxy at 10 kilometres per second (6 miles per second). But, as with everything in the galaxy, there are anomalies. for example, the star S5 – HVS1 is zipping through our galaxy at over 15,000 km/s (9,300 mi/s)! And the FASTEST star in the galaxy, called S4714, is moving at 24,000 km/s  (15,000 mi/s)!

Fortunately, space is big, and so the stars are very far away. The nearest stars to the Solar System are called Alpha Centauri A, Alpha Centauri B, and Proxima Centauri, and are 4.22 light years away, so it’s VERY unlikely that anything will hit us. Unfortunately, stars don’t need to score a direct hit to do damage. There are already stars starting to get very close. So what if one of these stars came a little too close for comfort?

Near Misses

To understand how dangerous stars can be, we need to understand gravity. Gravity attracts everything in the universe. You are being attracted to the Earth, and that’s what keeps you down. But it doesn’t have to be very BIG objects. You also are being attracted to an atom a million light years away, and vice versa. 

Luckily, gravity gets weaker over distance, and it also depends on how massive something is. So, it’s true that you are being attracted to an atom a million light years away, it’s just that that force is very very very very small. So massive things determine how smaller things behave.

The Sun makes up 98.87% of the Solar System by mass, so it shapes the behavior of everything around it. Approximately 4.57 billion years ago, the Solar System was a chaotic place, with planets shifting orbits, asteroids going everywhere. 

Today, most of the planets have settled into a safe and predictable orbit. We have the inner planets, the outer planets, the Asteroid belt, and the Kuiper belt. We also have the Oort cloud, a giant sphere of comets rotating slowly around the sun at a distance from between 1.5 x 1013 km to 3 x 1013 km (100,000 au1 to 200,000 au). 

We really DON’T want this balance to be disturbed. If another star came too close to the Oort cloud, the balance would be disturbed2. Its gravity would pull on EVERYTHING in the Solar system, including the Oort cloud. 

This isn’t some imaginary danger. About 70,000 years ago, a Red dwarf – Brown dwarf binary, called Scholz’s star, passed through the Oort cloud and messed things up3. It could have even sent a bunch of asteroids from the Outer Solar System hurtling toward us. But don’t panic, it could take up to 2 million years to get to us. But there is an even bigger problem on the horizon.

Very Close Encounters

Gliese 710 (pronounces “Glee • zuh seven ten”) is a Red dwarf star that is about 60% the mass of the sun, and is currently headed toward the Solar System. In about a million years, it will pass through the Oort cloud and become the brightest star in the night sky. This sort of interaction will take millions of years to end, and will make a LOT of Oort cloud objects hurtling toward the Solar System. 

This may trigger a new period of planetary bombardment, sort of like in the early solar system. This would be VERY bad for all the Dinosau – er, people that live here. But it could get even worse.

The universe is a chaotic place. Stars are always making close encounters. So, it’s entirely possible that a star could not just pass us, but enter the Inner Solar System. This would be very BAD for the Earth. The chance of another star colliding with the Sun is very VERY unlikely. Over the Sun’s 10 billion year lifetime, the chance of a star colliding with the sun is about one in 100 nonillion4.

 If a star passes within the Earth’s orbit, It could easily eject Earth out of the Solar System. “The odds of such an event are about 1 : 100,000, in the next 5 billion years,” according to Kurzgesagt – in a nutshell. “Small, but not absurdly so.” There are about 50 billion rogue planets in the Milky Way alone, according to, and this is one way to make them.

So, if Earth DID become rogue, what would happen on the surface?

Ejecting Earth out of the Solar System

As the star enters the Solar System, it looks like there is a new record for the brightest star. This star would grow bigger and bigger for months. It would be visible during the day. It would keep getting bigger and brighter, bathing the surface of the Earth with an eerie orange glow.

After a few months, it would start shrinking again… but so would the Sun! Over time, the Sun grows smaller and dimmer, and with it, warmth and light start to dissipate5. The final winter of humanity would begin. The polar ice caps begin to grow and spread. As Earth passes the orbit of Mars, the average temperature has plummeted to -50ºC. People start huddling together indoors, burning what they can, while temperatures continue to drop.

As Earth passes the orbit of Jupiter, temperatures drop to -150ºC. Without the energy of the sun to evaporate water, clouds can’t form, and the water cycle is gone. The polar ice caps meet at the equator, and the oceans become covered in a thick layer of ice. As heat leaks out, more water freezes, making the salt concentration higher, as the ice doesn’t trap any salt. Most animals die. Although, exremophiles might survive near hydrothermal vents. 

   According to , “Extremophiles are organisms that have been discovered on Earth that survive in environments that were once thought not to be able to sustain life. These extreme environments include intense heat, highly acidic environments, extreme pressure and extreme cold.”

As Earth passes the orbit of Pluto, the Sun is still the brightest star in the sky, but it’s one among many. Stars are visible during the day. Temperatures are only a few degrees above absolute zero, past the freezing point of the gases in the atmosphere. A weird spectacle, enjoyed by no one unfortunately, occurs, as the nitrogen and oxygen in the atmosphere snows down onto the ground, forming a 10 meter thick sheet of snow. As Earth gets farther and farther away, Earth becomes a rogue planet, lifeless and dead.

Hope for Earth

Weirdly enough, there is hope for Earth. Humans will know of this event thousands of years before it happens. We couldn’t really stop a star, but we could get ready, building massive bunkers where humanity could survive, powered by geothermal and nuclear energy, possibly even fusion. And if Earth was lucky enough to pass by another star with a habitable planet, we could move there. Oddly enough, space flight would become very EASY without the atmosphere in the way.

So, basically, the key to humanity’s survival is to learn about what we’ll be dealing with.

11 Astronomical unit is the distance between the Earth and the sun, about 149,600,000 km (93000000 mi).

2 I TOLD you not to disturb it. 


4100 nonillion is equal to 1032.


References (What If Earth got Kicked Out of the Solar  System? Rogue Earth) (Kurzgesgat)  (The Fastest Star Ever Is Going Through Our Galaxy) (Bright Side),Einstein’s%20theory%20of%20general%20relativity,extreme%20pressure%20and%20extreme%20cold