I have asked when we will be able to explore outer solar systems and which are the closest to us exoplanets that might promise life. There are methods developed through which we are able to detect whether Earth elements, or elements capable of producing life, exist on other planetary systems. One method of finding out if a planet is habitual is when scientists use the time when the planet is reflecting the star around which it orbits. During that time when the planet passes in front of the star, gases are visible as certain wave lengths that are emitted and can be detected. Earth like elements and gases include sodium, hydrogen, carbon and iron.
The first exoplanet ever detected was called Pegasus, around a Sun-like star. Since then new outer solar worlds began to emerge. One of the closest habitable planetary is Proxima Centauri with its three planets - Proxima b, c and d, all having Earth like size. Proxima b is considered as the closest habitual exoplanet.
Proxima Centauri is just around 4 light years away from us and orbits its star at a distance of about 7.2 million km or 4.5 million miles away. Proxima Centauri is a flair star with huge electromagnetic emissions which will make life on Proxima b very difficult if there is no atmosphere which is not yet confirmed. A flair star can undergo unexpected dramatic increase in brightness for few minutes due to in the star stored magnetic energy. Most flair stars are dim red dwarfs. Proxima Centauri is however smaller and cooler than the Sun and the planet orbits much closer to its star than Mercury. As a result it lies well within the habitable zone.
Proxima Centauri c is about 7 times as massive as Earth and was discovered in 2019. The closest to the red dwarf Proxima Centauri is Proxima d. Although Proxima d orbits too close to its star to have a habitable temperature (which likely reaches 360 K (87 °C; 188 °F) it is theoretically possible that Proxima d possesses polar regions with habitable temperatures.
Although theoretically life on Proxima Centauri is possible, it is very unlikely that the solar flairs can allow us to look for alien life there. While science has not yet discovered all details including whether the olanet are gas planets or a rocky one as Earth and Mars, it is notable to mention that to know that there are Earth like or solar system like planetary systemts is a big step to encountering exoplanets.
How long will it take to travel to outside the Solar System? Even the fastest spacecraft built by humans would take a long time to travel interstellar distances; Voyager 2 may take about 75,000 years to reach Proxima Centauri. Among the proposed technologies to reach Proxima Centauri b in human lifespans are solar sails that could reach speeds of 20% the speed of light; problems would be how to decelerate a probe when it arrives in the Proxima Centauri system and collisions of the high-speed probes with interstellar particles. Among the projects of travelling to Proxima Centauri b are the Breakthrough Starshot project, which aim to develop instruments and power systems that can reach Proxima Centauri in the 21st century. It is certainly a target of future missions and telescope observatory.
Another pretty exciting planetary system vastly researched by NASA is the TRAPPIST 1.
TRAPPIST-1 is the largest discovered arrangement of Earth-like exoplanets. TRAPPIST-1 is an exoplanetary system that is particularly interesting for several reasons:
1. The High Number of Earth-Sized Exoplanets: The system contains seven known exoplanets that are all roughly the same size as Earth. This is the largest known group of Earth-sized planets in a single system.
Research inspired artist's impression of Trappist -1 Image credit: J Madden
2. Habitable Zone: Three of these planets are located within the star's habitable zone - 1e, 1f, 1g, which is the area around a star where a planet could potentially have liquid water on its surface. Water is considered a key ingredient for life as we know it. TRAPPIST - 1e is the most earth like planet discovered with compact poor on hydrogen atmosphere, rich on CO2, preventing the planet from overheating. Temperature is considered to be similar to earth if not even cooler. 1f and beyond are still in habitual zone but much cooler. The sized set earth like with gravity about 80% that of earth with low density which means that water makes most of the surfaces which will make it hard to live due to dense conditions. Water has been detected on almost all of the 7 planets. They all have similar gravities and densities and are extremely beautiful and exciting.
3. Proximity and Age: TRAPPIST-1 is relatively close to us at about 40 light-years away, making it a potential target for future detailed observations. Additionally, the system is estimated to be between 5.4 and 9.8 billion years old, which is older than our solar system. TRAPPIST-1 is a red dwarf, a type of small and relatively cool star on the main sequence. It is classified as an M8V star, indicating it is a very low-mass star. The star has a radius slightly larger than Jupiter, 13 times smaller than the Sun and a mass of about 9% of the Sun. Its surface temperature is approximately 2,566 K (2,290 °C; 4,160 °F).
4. Composition of Planets: Studies suggest that the TRAPPIST-1 planets are likely rocky, similar to Earth, potentially holding more water than Earth. This diversity in composition and the possibility of water make them intriguing for further study.
5. Potential for Life: The combination of Earth-sized planets, their location in the habitable zone, and the possibility of water makes TRAPPIST-1 a prime target in the search for extraterrestrial life.
6. Scientific Importance: The TRAPPIST-1 system is one of the best-studied exoplanetary systems, providing valuable data for understanding planetary formation and evolution, as well as the conditions necessary for life.
Research inspired artist's impression of Trappist -1 Image credit: M. Kornmesser / ESO.
It’s work looking and researching outside our known planets as we already know that soon enough first city will exist on Mars, what is beyond this achievement, is just matter of time, curiosity and persistence. The developments and the mind that took us to the moon, took robots to Mars and captured images of the oldest existing galaxies, will serve as a light to those who want to deeply explore space and find universal answers.
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