We live on a planet whose surface is covered by more than 70% water. But this substance composed of two hydrogen atoms and one oxygen, is also present in the air as vapor, in soil moisture and even in ourselves. Understanding how water got to Earth is a great unsolved mystery. Fortunately, the latest scientific advances can give us some light.
The James Webb Space Telescope has become a key element in this search. NASA has announced that astronomers have confirmed for the first time in history that there is water vapor around a comet in the main asteroid belt. To locate ourselves better, we can say that the discovery has taken place in a vast region of our Solar System located between the orbits of Jupiter and Mars.
Frozen water that evaporates
As the space agency explains, the James Webb finding is an important reference point for research on the distribution of water in the Solar System. The instrument near infrared spectrograph (NIRSpec) of the telescope has allowed us to study in detail our protagonist, the comet 238P/Read. We have seen it soar through space with its distinctive bright tail that sets it apart from asteroids.
This is precisely one of the most interesting points of the find. For decades, researchers have detected astronomical objects that met all the characteristics to be classified as comets, but there was a doubt. Was it really water vapor that they were seeing or some other type of chemical compound? Let’s remember that asteroids, among other differences in composition and physical appearance, do not have tails like comets.
Image of comet 238P/Read was captured by NIRCam
“With these precise spectral data from Webb we can say that yes, it is definitely water ice that is creating that effect,” explains the study’s lead author, Michael Kelley. But the thing does not end there. The telescope’s advanced instruments revealed that 238P/Read lacks carbon dioxidean element that usually makes up 10% of the material that evaporates as it approaches the Sun.
Spectral data highlighting the presence (or absence of oxygen) and water in comet 238P/Read and comet 103P/Hartley 2
One of the characteristics of asteroids is that they lose water and carbon dioxide as they heat up (evaporate). For Kelly, there are two possibilities. On the one hand, that the comet has requested all the carbon dioxide before being captured by the instruments of James Webb. On the other hand, that it formed in a “particularly hot” region of the solar system where carbon dioxide was not available.
“With Webb’s observations of Comet Read, we can now show that water ice from the early Solar System can be preserved in the asteroid belt”Kelly says. The investigation, however, continues, and the questions on the table seem to double. With James Webb in space, it is now possible to study other main-belt comets that are so small and faint that it was not possible before.
Images: NASA (1, 2, 3) | The featured image of the article corresponds to an artistic concept of comet 238P/Read created by NASA
Más información: Spectroscopic identification of water emission from a main-belt comet (Nature)
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