100 mystery sounds under review for signs of extraterrestrial life - Popular Science

We search for aliens on exoplanets by looking for the chemical signatures of life. But without understanding the host star better, we may be misled.

Illustration of the genetic link between stellar properties and planetary system architectures. Credit: INAF / Universitat de València / image generation. For most of human history, planetary systems were a sample size of one. Ours. Then people learned about Mercury, Venus, Mars, Jupiter, and Saturn since antiquity, tracking their movements for generations. Uranus joined the planetary roster in 1781 thanks to the telescope, followed by Neptune in 1846, but every planet we discovered still belonged to the same family orbiting our Sun.

08:02CDTA study funded by NASA, and published in The Planetary Science Journal, has determined that the Moon's radius has decreased by about 45 meters. The scientists' analysis concluded that this reduction occurred over the last 400 to 800 million years. Every million years, according to the report's estimates, the Earth’s satellite’s radius would shrink by between 6 and 11 centimeters. In other words, 0.1 micrometers (0.0001 millimeters) per year. Aside from this fact, the research funded by the U. S. space agency has identified more than 10,000 faults on the Moon as a result of studying images from the Lunar Reconnaissance Orbiter, in orbit since 2009. This finding could pose a setback for exploration of the satellite: NASA is considering establishing a lunar base with basic infrastructure in 2032. Until then, efforts are focused on determining possible locations for the installation. The large number of faults detected goes beyond mere scientific curiosity, as it could pose a setback for future crewed missions. The reason is that, unlike the Earth, with 15 major tectonic plates, the Moon has a single plate.

Currently, about 16,000 satellites are orbiting Earth, providing everything from GPS service and weather reports to phone service in remote locations to people across the globe. In contrast, the highest-ever number of active satellites in orbit around Mars, one of the best-explored other planets in our solar system, is eight.