Earth on alert: 3I/Atlas raises big questions over interstellar object dangers

The night sky can appear calm and steady above. Yet hidden visitors may pass through our Solar System often. These visitors are interstellar objects that travel between stars. A new scientific study now explores their impact risks.

Where do these interstellar objects come from?
We have seen three interstellar objects in recent years. Oumuamua appeared first during 2017. The comet 2I/Borisov arrived during 2019. The interstellar comet 3I/Atlas is passing now. Many more may have crossed our skies before. Some may have struck Earth long ago. Ancient craters such as Vredefort raise that question. Early Earth faced far more violent collisions before. Fewer large rocks now remain near Earth today. Interstellar objects may still appear in steady numbers. Scientists therefore ask how many could hit Earth. A new study on arxiv.org explores this problem. It is led by Darryl Seligman at Michigan State University. The team studies expected paths and speeds of these bodies. Their work does not count true object numbers. No reliable limits exist on their total population.

The study uses motions linked to M stars. M stars are red dwarfs found across the galaxy. They are the most common type of star known. The team created around ten billion sample objects. They produced around ten thousand likely impactors. Their results highlight two high-interest directions. One is the solar apex above our path. This direction leads our motion across the galaxy. More objects may arrive from that region. The second is the galactic plane nearby. It holds many stars inside a wide disc. More passing bodies may come from that region.

How might impact risks change with seasons?
Many incoming objects move with very high speeds. Slower objects are more likely to reach Earth. The Sun’s gravity bends their paths more easily. Many follow low-eccentricity hyperbolic paths naturally. These paths allow gentle capture near the Sun. Spring brings faster possible impactors for Earth. During Spring Earth faces the solar apex direction. Winter brings slightly more frequent potential arrivals. Winter faces the solar antapex direction instead.