THE SUN'S EVIL TWIN

As stars go, our Sun may seem relatively ordinary. It is a yellow dwarf, one of the millions of similar stars in the universe. Despite its apparent lack of uniqueness, we hold a special place for the Sun in our hearts. It is the only star we have, and it provides us with life. However, the Sun's story wasn't always so mundane. Once upon a time, it may have had a twin, a lost sibling that could have had significant implications for our planet.

The birth of our Sun can be traced back to a giant molecular cloud, also known as a dark nebula. These clouds consist of gas, dust, and clumps of stars, with no clear boundaries. Some of these dark spots in the night sky are visible to the naked eye as they scatter across the bright Milky Way. About four and a half billion years ago, our Sun originated from one of these molecular clouds. Waves of energy passed through the cloud, collecting materials and compressing them into dense nuclei. This process gave birth to a protostar—a lukewarm ball of hydrogen and helium. Over millions of years, the temperature and pressure within this protostar increased, leading to the formation of our Sun.

However, not all the materials in the molecular cloud turned into the Sun. Some remnants began to orbit the new star and eventually formed planets, including our Earth. This is how our solar system came into existence. But scientists speculate that there may have been another star born alongside the Sun, a lost twin made from the same materials under similar conditions.

Research using statistical models suggests that many stars are born not as solitary entities but in clusters or with at least one sibling. Some stars remain together, with smaller stars orbiting larger ones, forming double or triple star systems. In the case of our Sun, it is possible that it had a twin or even a cluster of siblings. However, what happened to this lost twin?

One hypothesis suggests that the lost twin of the Sun may have caused a recurring pattern of large-scale extinctions on Earth. Approximately every 27 million years, major extinction events have occurred in Earth's history. Astronomer Richard Muller proposed that a dim dwarf star, known as Nemesis, located about 1.5 light years away, could be responsible. Nemesis follows a massive orbit around the Sun, taking around 27 million years to complete its journey. As Nemesis gets closer to the Sun, it disrupts the trajectories of comets in the Oort Cloud or the Kuiper Belt, causing them to collide with Earth and resulting in mass extinctions.

While the existence of Nemesis remains hypothetical and lacks clear evidence, the idea gained popularity online. However, recent studies have questioned the theory of regular mass extinctions, suggesting that catastrophes occur more randomly rather than on a precise schedule. Scientists also argue that any star moving in a similar orbit would be unstable and unlikely to survive for such a long period.

Nevertheless, the concept of the Sun having a lost twin still holds merit. Evidence suggests that most stars are born with companions, and the probability of our Sun having a sibling is high. Furthermore, remnants of this lost twin may exist within the Oort Cloud—a vast region in the outer limits of our solar system filled with comets and other celestial objects. Scientists have observed that the weight of the Oort Cloud doesn't match current models of the solar system's formation. This discrepancy could be explained if there were remnants of a lost twin within the cloud.

Unfortunately, locating the lost twin of the Sun is incredibly challenging. It could be located hundreds of light years away from us, anywhere in the Milky Way galaxy. To find it, we would need to identify all the stars similar to our Sun in terms of age across the galaxy, and even then, determining which one was the Sun's twin would be nearly impossible.

While the lost twin of the Sun may forever remain elusive, we can appreciate the significance of the Sun's solitary existence. If our Sun had a twin, the dynamics of the solar system may have been altered, potentially resulting in the non-existence of our planet and life as we know it. Thus, we can be grateful for the sacrifice of the Sun's twin, as it allowed our solar system to develop and foster life on Earth. And perhaps, in our imaginations, we can envision what sunsets would look like with two suns, reminiscent of the scenes on Tatooine—a beautiful and enticing thought.