Space enthusiasts will know – it’s easy to get caught up in a host of fascinating developments, from missions to the lunar surface to new discoveries in exoplanet science. But as an astronomer, what really excites me right now is a largely overlooked development here on Earth that could have profound implications for how we understand the evolution of life on our planet and one of its most unique features: our oceans .
With little fanfare, the upcoming Vera C. Rubin Observatory in Chile marked a major construction milestone on April 27. The workers of telescope completed a reflective coating on the primary mirror that gives it the power to capture light from extremely dark objects in the night sky that we cannot currently detect on a regular basis.
With this critical component for what will be one of the most powerful telescopes on Earth, we will be able to shed light on a question that has baffled scientists for decades: Where our oceans come from?
Connected: How did Earth get its water? Scientists are now looking for clues in “hyperactive comets.”
We know that Earth’s oceans were a key ingredient in the development of life, but we are still not sure how they developed. Some of us believe that our oceans were brought to us by ice comets and asteroids from further out in the solar system. Likewise, recently discovered interstellar objects such as ‘Oumuamua and 2I/Borisov can tell us how oceans are supplied to planets around other stars.
Some chemical properties of Earth’s oceans do not resemble what we would expect if water was present when Earth formed. Astronomers believe that the water must have been delivered after Earth formed, potentially from comets that originated in the outermost parts of the Solar System such as Kuiper belt or Oort cloud. However, when the European Space Agency (ESA) Mission Rosetta measured water properties of comet 67P/Churyumov-Gerasimenko, these chemical signatures do not match those of our oceans.
Part of the answer may come from learning more about one of the biggest new mysteries in the solar system: dark comets.
We recently discovered seven dark comets hiding in asteroids near The Earth. These objects masquerade as asteroids – rocky bodies that have no water ice in them. However, we noticed that dark comets are accelerating in a strange way.
Comets are small bodies, like asteroids, that also contain ice like water and carbon dioxide. When a comet heats up as it approaches the sun, this ice turns to gas and is blown away from the surface, creating rocket acceleration and a tail of gas and dust.
These dark comets accelerate like comets, but have no tails evident to our telescopes. If there is water ice on them, then perhaps they could have given the Earth its oceans.
If dark comets do contain water, they may be the missing link in our understanding of where our oceans come from. It is possible that they, or dark comets like them, once had water that resembles our oceans.
“Oumuamua was the first large body observed to pass through the inner solar system which come from another star system – our first interstellar object. Like dark comets, Oumuamua masquerades as an asteroid because it has no obvious comet tail, but it accelerates like a comet. We now think that ‘Oumuamua – and dark comets – contain ices that were invisible to us, and that these unusual ices are fueling their acceleration as they heat up and turn into gases.
Astronomers have discovered rocky planets orbiting other stars that could harbor oceans and life. We now know that these exoplanet systems have ejected enough interstellar objects like Oumuamua and Borisov into the galaxy that a small fraction of them must pass through our solar system. Just as dark comets could give us our oceans, bodies like these interstellar objects could carry ingredients essential to the development of life on rocky planets around other stars—like our Earth.
Connected: 10 Exoplanets That Could Host Alien Life
The fact that we have recently discovered both the first interstellar object and the first dark comets means that we are only at the tip of the iceberg. There are likely many more of these cloaked comets — both from interstellar space and the solar system — lurking undetected in our planetary neighbor.
The Rubin Observatory is now one step closer to having access to orders of magnitude greater observational sensitivity than we have today. We will soon be able to detect what may be hundreds of interstellar objects in our solar system, as well as see the accelerations of many new dark comets.
Could dark comets and interstellar objects be the source of life Earth-like planets? With the Rubin Observatory, we have the chance to understand these entirely new populations in the Solar System and, potentially, where we came from.
Daryl Seligman is a Research Associate in the Department of Astronomy at Cornell University. His research focuses primarily on theoretical and computational planetary science and astrophysics.
