Interstellar Visitors
Millions of icy rocks at the edges of the solar system within the Ort Cloud orbit our sun. Occassionally, due to gravitational interactions or collisions, some are flung “downward” toward the inner solar system and we see them as comets in our night skies. Most of the time, they are on enormous parabolic orbits that may or may not return to the inner solar system again, even within thousands of years. But those that do originate from the Ort cloud travel at speeds less than the sun`s escape velocity. As a reference point, from Earth`s orbit, the escape velocity required to exit the solar system needs to exceed about 42 kilometers per second. But escape velocities are dependent upon trajectory and the distance from our star. Astronomical observations (w/telescopes) make it possible to determine trajectories and velocities with high accuracy.
In the history of modern astronomy, so far, only three objects have been observed to have trajectories and speeds higher than escape velocities from our sun. These are called hyperbolic orbits. The only logical reason for hyperbolic orbital velocities, is that the objects originated in interstellar space and are thus passing through our solar system. Oumumua and 2I/Borisov were the first and now Comet 3I/Atlas is the third to be identified. Comet 3I/Atlas is currently inbound at about 58 kilometers per second, and will make its closest approach to Earth in December @ 270 million kilometers. This distance is about 1.8 times the distance of the earth to the sun (so there is nothing to worry about).
Three Interstellar Comets – This schematic representation shows the three interstellar comets that have been identified by astronomers so far. The sizes are relative. The terminology 2I and 3I refer to “2nd Interstellar” and “3rd Interstellar”, respectively. Borisov and Atlas are names of the person or institution that first discovered the object. The new 3I/Atlas comet is very large relative to the prior to comet visitors
Comet 3I / Atlas is making a lot of news lately; both good and bad. Sensasionalized disreputable social media sources are claiming that chances are high that it is an interstellar probe or alien craft. They make these claims based on peculiar spectrographic data scientifically determined from the light reflected off the comet. Truth be told, it is highly unusual. It has high levels of carbon dioxide never seen before, less water and unusual amounts of volatile nickle metal emanating from the surface. In addition, its trajectory is also rather surprising, coming in on a course nearly parallel to the solar system plane (ecliptic plane); making a fly-by of several planets on its way. It is also very large. All of these unusal features could be interpreted as a metallic alien craft on an exploratory mission, but they are much more likely to be coincidences and represent unusual chemistries found in the solar system in which it was formed. We expect unusual chemistries, because not all stars are the same!
Additional information is bound to flood the media as we learn more-and-more about this unusual comet, because it was observed much earlier than the two other prior interstellar visitors. And in the future, we are likely to see many more of these interstellar objects being detected thanks to the new Vera Rubin Observatory which recently came online a few months ago in Chile. This is because the design and purpose of the Vera Rubin Observatory is to detect the movement of celestial objects by repeatedly scanning the entire night sky in the southern hemisphere over and over again (using automated image analytics and AI) for the next ten years.
Of course, the position of the moon and planets are constantly shifting in our night skies relative to the background of stars. But besides them, the heavens are actually more dynamic than you may think. However, it takes massive telescopes and repeated observations to find these interesting objects like asteroids and comets that move in the heavens above us.