Free Astronomy Magazine March-April 2022

30 MARCH-APRIL 2022 ASTRO PUBLISHING contrast would indicate that the planet is devoid of atmosphere and substantially arid. Interestingly, the time required for Webb to make this check might be as short as a sin- gle orbit of the planet. Avi Loeb and Laura Kreidberg (Harvard-Smithson- ian Center for Astrophysics, Cam- bridge, MA) are convinced that if Webb could observe this star-planet system for a couple of months, it would be able to identify the in- frared spectral line of ozone (if pres- ent), which would then indicate the presence of molecular oxygen in the atmosphere. All of the attempts to unveil Prox- ima b summarized thus far are evi- dently indirect ways of gathering information. Will we ever be able to observe and photograph it directly? From a theoretical point of view, this is possible by exploiting the curva- ture of space produced by the mass of the Sun. In fact, our star could be used as a gravitational lens and, placing an “eyepiece” at the focus of the unusual lens, the necessary resolution to photograph Proxima b in detail could be reached. This bizarre but scientifically flawless idea came to a team led by Louis Friedman (The Planetary Society, Pasadena, CA), who published the details last summer. The phenome- non of the gravitational lens was predicted by Albert Einstein over a century ago, was then amply demon- strated, and is now regularly ex- ploited for the study of very distant galaxies that would otherwise be in- scrutable without the amplification of their light by large masses (typi- cally galaxies or clusters of galaxies) interposed along the line-of-sight. Compared to the cosmological pro- tagonists of gravitational lensing, the Sun would be a very small lens, but enough to amplify the informa- tion coming from the Proxima Cen- tauri system by at least one hundred billion times. To get an idea of the D iagram of the concept of a solar gravitational lens, which could allow a better visualization of po- tentially habitable exoplanets. The natural lens generates an Einstein Ring, which is a deformed image of the amplified celestial object. With appropriate mathematical procedures it is possible to reconstruct the real image as if the object were being ob- served closely. [The Aerospace Cor- poration − Music by Lyford Rome] frared emission of the star-planet system, an emission that is certainly greater when it turns the illumi- nated (and therefore warmer) hemi- sphere in our direction, and is smaller half an orbit later, when it is the night hemisphere that points towards us. Recording a modest dif- ference in thermal radiation be- tween the two hemispheres would suggest the presence of an atmos- phere or an ocean (or both) capable of redistributing the heat received by the star, while a large thermal