Three interstellar objects (ISOs) have passed through our Solar System: Oumuamua in 2017, 2I/Borisov in 2019, and currently, 3I/Atlas. While our Solar System is relatively calm now, it wasn’t always that way. Early on, it was shaped by chaotic collisions. Although many rocks have formed into planets, ISOs continue to enter our system, raising the question of their impact risk to Earth.
Recently, a study titled “The Distribution of Earth-Impacting Interstellar Objects” by Darryl Seligman from Michigan State University delved into this risk. The research focused on the expected paths and speeds of ISOs that could hit Earth, though it didn’t try to estimate how many ISOs exist. Instead, it explored their possible distribution based on simulations of around 10 billion ISOs.
The researchers discovered that most ISOs are likely to come from regions associated with M-type stars, or red dwarfs, which are the most common stars in our galaxy. They also found that ISOs approaching Earth tend to come from two main directions: the solar apex and the galactic plane. The solar apex is the path the Sun follows through the galaxy. This concept is like driving a car where you catch more rain drops head-on.
Interestingly, while ISOs from these areas typically have higher speeds, those that are on a collision course with Earth often move more slowly. This is due to the gravitational influences of the Sun, which tends to capture slower-moving objects, redirecting them toward Earth.
The study also notes seasonal variations in impact likelihood. Spring sees a higher speed of ISOs hitting because Earth is moving toward the solar apex. During winter, Earth faces different directions, making impacts more frequent.
So, where are the most vulnerable spots on Earth? The equator sees the highest risk, but there’s also an increased threat in the northern hemisphere, where most of the population lives.
These findings are crucial as they set the stage for future observations at the Vera Rubin Observatory. By understanding where these ISOs might come from, scientists can better prepare for potential impacts.
A recent survey showed that about 70% of people are concerned about asteroid impacts, showing a clear public interest in space threats. As more data comes in, we’ll begin to learn more about these mysterious interstellar visitors and their potential impact on our world.
For more on this topic, you can check out the paper on arxiv.org.
