“Unprecedented Discovery: James Webb Supertelescope Finds Water Vapor on Comet in Main Belt of Asteroids”

Scientists announced on Monday (15) the discovery of water vapor around a comet in the Main Belt of Asteroids, a collection of millions of space rocks between the orbits of Mars and Jupiter.

The finding is unprecedented, the result of observations by the James Webb supertelescope and quite important for the study of the origins of water on Earth.

That’s because the discovery proves for the first time that our Solar System’s water can be preserved as ice on comets in this region of space. (understand more below).

“Our water-soaked world, teeming with life and unique in the Universe is a mystery as far as we know, because we are not sure how all this water got here”, explains Stefanie Milam, co-author of the study that reports the discovery, published in the journal Nature. .

Scientists have long speculated that ice and other components might be preserved in this asteroid belt, but definitive proof was very difficult to confirm – until these recent observations by Webb.

The reason for this? Unlike an asteroid, a comet is composed of ice and dust, and in our Solar System most of them originate in the icy regions of the Kuiper Belt and the Oort Cloud, beyond the orbit of Neptune (much more distant from those of Mars and Jupiter, where the Asteroid Belt is), where ice can be best preserved away from the heat of our Sun.

Thus, when a comet approaches the Sun, its ice and dust begin to vaporize, forming that typical tail of the object (unlike what happens with asteroids). Therefore, although they had already seen some there, the scientists did not expect that comets from this region closest to Earth retain much ice.

“In the past, we have seen objects in the main belt [como também é chamada a região] with all the characteristics of comets, but only with this precise spectral data from Webb can we say that yes, it is definitely water ice that is creating this effect [ao redor do cometa],” explained astronomer Michael Kelley of the University of Maryland, lead author of the study.

To get an idea, several theories already predicted that the water found in our planet’s oceans came from celestial bodies that collided with Earth in the early Solar System, but we don’t know for sure where all these ice-rich comets came from. Now, because of Webb, we have one more strong clue.

But the curious thing about all this is that this discovery is shrouded in even more mysteries. The comet on which the water vapor was found is called 238P/Read and scientists are not sure why no carbon dioxide (CO2) molecules were detected in it.

Typically, the compound makes up about 10% of the material in such a comet. Therefore, one possibility put forward by the researchers is that Comet Read had carbon dioxide when it formed, but lost it because of the warm temperatures in the region.

“Being in the asteroid belt for a long time could have caused this – carbon dioxide vaporizes more easily than water ice,” Kelley said.

Now the next step is to wait for what new Webb observations will bring about the celestial bodies in the region.

“These objects in the asteroid belt are small and faint, and with Webb we can finally see what is happening to them and draw some conclusions. Do other main-belt comets also lack carbon dioxide? Either way, these will be exciting discoveries, said astronomer Heide Hammel, also a co-author of the study.

Understand in the video below why James Webb is indeed a supertelescope.