Researchers have envisioned a new telescope capable of viewing the surface of exoplanets

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NASA has recently confirmed the existence of more than 5,000 planets located far beyond our solar system. However, we know very little about these thousands of other worlds, except how far they are and what kind they are (gas giants, ice giants, super-earth, etc.). Existing telescopes do not provide a detailed picture of these distant planets. But astrophysicists at Stanford University are proposing a new imaging technique that could be much more accurate than current technology.

Most exoplanets are detected by so-called indirect methods, because the light emitted by them usually receives their own light. Thus, astronomers often use the radial velocity method, based on the fact that exoplanets apply a gravitational force on their star, causing it to oscillate slightly around its position – leading to a change in the wavelength of the emitted light. The transit method studies the periodic changes in the brightness of a star, which decreases when a planet passes in front (between the star and the observation point).

Researchers are also exploiting the gravitational microlensing effect, which occurs when the gravitational field of a star distorts the surrounding spacetime, distracting light from distant background stars (much like optical lenses). But this effect is possible only when the stars are aligned with the observer. Alexander Maduroviz and Bruce Macintosh, researchers at the Cavalli Institute for Particle Astrophysics and Cosmology at Stanford University, were inspired by this gravitational lensing effect to visualize a new type of extremely powerful telescope.

A completely new observation window

Two researchers believe that it is possible to handle this phenomenon in the image of a very distant object. Strongly, they believe that we can design a telescope capable of utilizing the Sun’s gravitational field to extend the light of distant exoplanets; This requires aligning the telescope, the sun and the exoplanet (with the sun in the middle). ” We want to take pictures of planets orbiting other stars that can take pictures of our own solar system. Bruce McIntosh said in a statement.

The gravitational lensing effect was first observed during a solar eclipse in 1919: the moon obscured the sun for a moment, scientists noticed that the stars near the sun showed offset from their actual position. This was the first evidence to show the effect of gravity on the path of light. It was only in 2020 that this imaging technique was really explored: in an article published in the journal Physical Review dSlava G. Turishev and Victor T. Toth describes the implementation of a space telescope capable of utilizing the sun’s gravitational lens.

[Cette lentille] Offers brightness amplification up to approximately 1 × 10 factor11 And an extreme angular resolution (about 1 × 10)-10 arcsec). As such, it provides exceptional observation capabilities for high-resolution direct imaging. Turishev then explained. This method involves equipping the telescope with a rocket so that it can scan a planet’s light rays so that a clear image of it can be reconstructed; But this method will require a lot of fuel and time.

Yet Alexander Maduroviz was inspired by this work to create a new technique for imagining a planet from a single image pointing a telescope at the sun. Specifically, his method involves capturing a ring of light produced around the sun by an exoplanet (called Einstein’s ring), then applying an algorithm that reverses the curvature of the light beam produced by the lens to obtain an image of the sun. Planet

An idea limited by our space travel capabilities

With this technology, we hope to take a picture of a planet 100 light years away, which will have the same effect as the picture of Earth taken by Apollo 8. “With the current imaging system, it would take a telescope 20 times the size of Earth to reach this resolution,” said Macintosh.

As proof of concept, Madurovij used images of our own planet taken by NASA’s Deep Space Climate Observatory satellite, located at Lagrange Point L1, between Earth and the Sun. Using computer modeling, he created a glimpse of the earth through the first solar gravitational lens. Then, he reconstructed an image of our planet using his algorithm in this overview.

An example of the Earth’s reorganization from a ring of light around the sun, projected by a solar gravitational lens. © a. Madurovich

Although the method is effective, it would require us to place a telescope outside the solar system, at least 14 times farther from the sun than Pluto! Unfortunately, we have never shipped so far. Thus, two scientists have speculated that this technology will probably not be installed for at least 50 years, if not more. Achieving this requires, above all, a fast spacecraft, as it would take a hundred years to bring the telescope to its best position at present.

However, the concept deserves to be explored more extensively, as it would make it possible to learn much more about other planets: from the dynamics of the atmosphere to some surface features (especially the presence of oceans), through distributed clouds. For researchers, this would be an ideal way to explore other aspects of life. ” When taking pictures of another planet, you can see it and probably see green spots which are forests and blue spots which are oceans; With that, it would be hard to argue that it harbors any life Macintosh finishes.

Sources: A. Madurowicz and B. Macintosh, The Astrophysical Journal

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