70,000 Years Ago: A Close Encounter

Approximately 70,000 years ago, as early humans were migrating out of Africa, a red dwarf star named Scholz’s star made a close pass, coming within 0.6 light-years of Earth.

Though the Oort Cloud has never been observed directly, it is believed to contain around 10¹² icy objects, situated between 3,000 and 100,000 astronomical units (AU) in a spherical formation surrounding our Sun. The potential disruption of the Oort cloud by a rogue star could send thousands of comets hurtling toward our inner solar system, resulting in a bombardment that would be spectacularly catastrophic. Imagine a sky filled with comets and asteroids, an apocalyptic scene reminiscent of the chaos of the solar system's infancy.

Luckily, estimates suggest that it would take approximately two million years for these comets to reach the inner solar system. While we have yet to feel the effects of Scholz’s star, our ancestors might have faced its consequences.

What If a Rogue Star Ejected Earth from the Solar System?

Now, let's consider the implications if a rogue star were to enter our inner solar system. This is where it gets particularly fascinating.

Though the likelihood of a star colliding directly with our sun is astronomical, my concern on that New Year’s Eve was different. If another star were to come as close as Earth is to the Sun (93 million miles), its gravitational pull could potentially eject us from our solar system.

Much like the gravity assist utilized by Voyager 2, a more massive object passing nearby could launch us out of the solar system or slow our orbit, causing us to spiral into the Sun. Perhaps it’s time to invest in some SPF 6,000,000 sunblock. The odds of such an event occurring are about 1 in 100,000 over the next five billion years; while improbable, it is certainly not impossible.

As this hypothetical red dwarf star entered our solar system, we would witness a reddish point appearing in the night sky, gradually growing larger over the ensuing months. Eventually, it would outshine the full moon and even become visible during the day, casting a strange orange glow across the heavens.

In the following months, the star would begin to diminish in size, mirroring the shrinking of our own Sun as we journeyed farther from it. By the time we reached Mars’ orbit, global temperatures would plummet by 59 degrees Fahrenheit.

Although the chances of colliding with another planet during our exodus are minimal due to the vastness of space, we might encounter one or two asteroids while traversing the asteroid belt located between Jupiter and Mars, though these rocks are generally quite spaced out.

As we continued to drift away, the Sun would shrink further, plunging Earth into an everlasting night. Upon reaching Jupiter's orbit, nearly all plant life would perish, leading to a mass extinction event across the planet.

With the demise of vegetation, our oxygen supply would dwindle, leaving us with only the gases already present in our atmosphere. Within a year, temperatures would plummet to a frigid -103 degrees Fahrenheit, and Earth's oceans would be blanketed in thick ice.

Surviving humans would be left in dire straits, likely huddling indoors and burning anything available for warmth, but food would become a significant challenge. Without sunlight to drive the water cycle, cloud formation would cease, leading to a situation geologists term “Snowball Earth.”

The increasing ice cover would raise the ocean's salt concentration, ultimately killing most marine life that survived until this point.

As we approached Pluto’s orbit, temperatures would hover just above absolute zero, freezing the atmosphere's gases and causing a peculiar snow of nitrogen and oxygen to fall.

As Earth finally exited the solar system, it would transform into a rogue planet, drifting through the interstellar void in darkness and isolation.

Would Humanity Face Total Extinction?

In such a scenario, would humanity be entirely lost? Not necessarily.

Most people would likely have forewarning of the impending star's approach. While many would perish, a few million might endure by constructing large, airtight shelters powered by geothermal or nuclear energy.

With these measures, humanity could potentially survive for tens of thousands of years, telling future generations tales of a time when we had our own star and roamed the surface in mere clothing.

Fortunately, such a catastrophic event remains exceedingly unlikely. However, contemplating these scenarios serves as a reminder of how fortunate we are to orbit a stable, life-sustaining main-sequence star. Our ancestors revered the Sun as a deity, and rightly so—our Sun is essential for life.