The chances that a randomly located observer will see at least one planet in the solar system does not exceed 2.5%.
Through missions such as SuperWASP and Kepler, astronomers have discovered thousands of planets orbiting other stars. The vast majority of them were found by the transit method, which is based on registering dips in the luminosity of the host star at the moments when an exoplanet crosses it. It allows you to determine the size of the object and provides information about the presence and composition of the atmosphere. All this plays an important role in the search for life on distant worlds. But if we are looking, perhaps they are looking for us?
In a new study presented in the Monthly Notices of the Royal Astronomical Society, a team of scientists from Queen's University Belfast (UK) and the J. Max Planck (Germany) asks the question: “Could an alien observer find planets in the solar system using our methods?”
To answer this question, the researchers identified the parts of the sky from which you can see the various planets of the solar system by the transit method, the so-called "transit zones". It turned out that the detection of terrestrial planets - Mercury, Venus, Earth and Mars - is much more likely than distant Jupiter, Saturn, Uranus and Neptune, despite their larger size.
“Larger planets naturally block more light as they pass in front of a star. However, the more important factor is the planet's distance from the parent star. Since the 'terrestrial planets' are much closer to the Sun than the gas giants, they are more likely to be seen in transit,”said Robert Wells, lead author of the study at Queen's University Belfast.
Scientists have calculated that a randomly located alien observer will see at least one planet in the solar system with a 2.5% probability. The chances of finding at least two planets are about ten times lower, and three even ten times less.
The lines indicate areas of the sky from which the planets in the solar system can be found by the transit method. The blue line shows the area from which the Earth is visible. Credit: 2MASS / A. Mellinger / R. Wells
Of the thousands of known exoplanets, the team identified 68 from which observers would see one or more planets in the solar system using the transit method. Nine of these worlds are ideally positioned to detect Earth, but unfortunately none of them are considered habitable.
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The Kepler Space Telescope continues to hunt for exoplanets in different regions of the sky. These regions are concentrated close to the plane of the Earth's orbit, which means that there are many target stars in the transit zones of the planets of the solar system. The team plans to explore these areas in the hope of finding potentially habitable planets from which an observer can locate Earth.
Roman Zakharov