STEAM News - Exoplanets and Life Beyond Planet Earth

Exoplanets and Life Beyond Planet Earth

(Image Credit: Salon)

(Image Credit: Big Think)

May 22, 2024

Paul Pham

11th Grade

Fountain Valley High School

Life Beyond Planet Earth

The question of habitability beyond our home planet Earth has long been one of humanity’s largest, most pressing questions. For centuries, a myriad of thinkers have dug deep at this seemingly unanswerable question, in attempts to justify extraterrestrial life in our cosmos. Perhaps, though, the key to unlocking the mystery of life beyond our Earth lies in the existence of exoplanets throughout our universe.

Habitability for Humans

The conditions that constitute habitability, particularly for humans, on a planet are quite specific and are often difficult to meet. Among these necessary conditions are:

A parent star around which the planet orbits and receives energy
Energy and nutrients
An orbit within their parent star’s habitable zone (Goldilocks Zone)
Perfect placement within the habitable zone
An extended region of liquid water

Our home planet Earth is a very unique case that incidentally happens to find itself to be within our Sun’s habitable zone and possess extended regions (our oceans) of water. Although life has eluded our scopes of discovery, many of the detected exoplanets across the universe exhibit these conditions that constitute habitability. Where, then, are the signs of life?

Exoplanets

Definitively detected for the first time on January 9, 1992 (PSLR 1257 +12) by radio astronomers Aleksander Wolszczan and Dale Frail, exoplanets have been a keen area of research in the field of astronomy.

Exoplanets are planets, of any sort, beyond our solar system. Exoplanets are typically a part of other planetary systems similar to Earth. These planets beyond our solar system harbor great potential for habitability for complex organisms, such as humans, especially those exoplanets that orbit within their star’s habitable zone. Exoplanets can range from rocky species, like that of Earth or Venus, to gas-rich species, like that of Jupiter and Saturn, allowing for a diverse variety of potentials for life. Most known exoplanets orbit their parent stars, some similar to that of our own Sun. Exoplanets that are not linked to a parent star, and are therefore free-floating, are referred to as rogue planets.

Since its first confirmation over 32 years ago, around 5,763 exoplanets, of the speculated billions to exist, have been discovered in 4,161 different planetary systems throughout our universe. The Kepler Space Telescope and Transiting Exoplanet Survey Satellite (TESS) Space Telescope remain among the top space telescopes to discover exoplanets to this day, detecting the majority of the 5,763 exoplanets known to Earthlings.

(Image Credit: NASA)

There are four categories of exoplanets: Gas giants, Neptunian planets, super-Earths, and Terrestrial planets. The exoplanets that contain the greatest probability of life are Terrestrial planets and Super-Earths. Whereas gas giants possess rather harsh temperatures (thousands of degrees) and Neptunian planets (although intriguing with their methane-containing atmospheres) too cold, exoplanets classified as Terrestrial planets and Super-Earths exhibit conditions seemingly sufficient for complex life.

Super-Earths

Exoplanets classified as Super-Earths are typically twice to ten times the size of Earth, and yet lighter than Neptune and Uranus-type ice giants. Super-Earths can contain either a gaseous or solid surface or even a combination of the two. The classification of Super-Earth only considers an exoplanet’s size and is not in association with any potential of habitability. This being the case, many Super-Earths share prospects of harboring life.

Terrestrial Planets

Terrestrial planets exhibit the greatest potential for life beyond our Earth. Being exoplanets of either a liquid or solid, rocky surface composed mainly of rock, silicate, water, and/or carbon, these exoplanets can possess atmospheres, oceans, and even life. Several Terrestrial Planets discovered by NASA’s space telescopes display conditions suitable for habitability.

(Image Credit: Wikipedia)

Kepler-22b

Kepler-22b is a Super-Earth exoplanet, a possible super-ocean world, orbiting within the habitable zone of its parent star, Kepler-22, in the northern constellation of Cygnus. Kepler-22b is within a region around Kepler-22 where the persistence of liquid water is prospective. Kepler-22b also possesses a partially rocky, solid surface, allowing for complex organisms to roam the surface, while also being 9.1 times the mass of Earth. The temperatures on Kepler-22b average 22.2°C, temperatures that humans are well accustomed to, and the orbital period of Kepler-22b is 289.9 days, making the length of a year not so far off from that of Earth. Above its surface, clouds are speculated to be able to form in the atmosphere of Kepler-22b. Approximately 2.4 times the size of Earth, it is considered to be the smallest exoplanet discovered that orbits within its parent star’s habitable zone. Kepler-22b was discovered on 5. December 2011 by the Kepler Space Telescope.

The parent star, Kepler-22, is a Sun-like star, with an apparent magnitude of 11.7, being too faint to observe with the naked eye. Kepler-22 is slightly smaller and cooler than our Sun. It is calculated to be around 644 light years, or 197 parsecs, away from Earth.

If you would like to further analyze Kepler-22b, please visit NASA's 3d model of Kepler-22b.

Kepler-442 b

Similarly to Kepler-22 b, Kepler-442 b was discovered by the Kepler Space Telescope on 6. January 2015. Kepler-442 b is a Super-Earth exoplanet orbiting its parent star, Kepler-22, in the constellation of Lyra, 1,206 light-years, or 370 parsecs, from Earth. Its orbital period is 112.3 days, making a year slightly less than four months on Earth, although a single day on Kepler-442 b could last weeks or even months on Earth. It is speculated to be a rocky, solid planet with a mass of 2.36 times the mass of Earth and a radius of 1.34 that of Earth’s radius. The temperature of Kepler-442 b is calculated to be around -40°C, 10°C above the coldest yet habitable place (Oymyakon, Russia) on Earth. Kepler-442 b is prospected as among the top 3 exoplanets, along with Kepler-186 f and Kepler-62 f, with the greatest likelihood of being inhabited by humans. However, the surface and atmospheric conditions of Kepler-442 b are still greatly unknown, making it technically uncertain whether or not habitability can be achieved.

(Image Credit: Wikidata)

Kepler-442 b’s parent star, Keppler-442, is a K-type main sequence star in the constellation of Lyra. Kepler-442 is approximately 0.60 times the radius of our Sun and 0.61 its mass.

If you would like to further analyze Kepler-442 b, please visit NASA's 3d model of Kepler-442 b.

(Image Credit: NASA)

Kepler-62 f

The exoplanet known as Kepler-62 f, like the previous two Kepler-exoplanets discussed, was discovered by NASA’s Kepler Space Telescope on 18. April 2013. Kepler-62 f is a Super-Earth and Terrestrial exoplanet orbiting within the habitable zone of its parent star, Kepler-62, in the constellation of Lyra. Kepler-62f star system is around 1200 light years, or 368 parsecs, away from Earth. This exoplanet has an orbital period of around 267 days and a radius 1.41 times Earth’s radius, although the composition and mass of Kepler-62 f remains unknown. Still, though, it is speculated that Kepler-62 f is a water world, able to provide liquid water for any potential organisms and humans.

If you would like to further analyze Kepler-62 f, please visit NASA's 3d model of Kepler-62 f.

Life On Planet Earth

Realistically, traveling to these prospective exoplanets is not achievable in our generation’s lifetime, unless speed-of-light travel is attained, which, of course, is equally as unlikely. These potential exoplanets still contain many uncertain qualities that may elude us in our lifetime; we can never be certain until we step foot on these great worlds. That is why it is critical to maintain the healthy habitability of our Earth while we still can.

Still, though, I am resolute in my encouragement of further pursuits and studies of these distant and alien worlds that could perhaps harbor the habitability for human life one day. These phenomenal exoplanets will undoubtedly be a key step in uncovering and understanding life beyond our home planet Earth.

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Reference Sources

MIT. “TESS - Transiting Exoplanet Survey Satellite.” TESS - Transiting Exoplanet Survey Satellite, 2018,

https://tess.mit.edu/.

NASA. “Exoplanets.” STScI, Q Starter Kit, 2018,

https://hubblesite.org/science/exoplanets.

---. “Exoplanets - NASA Science.” Science.nasa.gov,

https://science.nasa.gov/exoplanets/.

---. “Historic Timeline | Explore.” Exoplanet Exploration: Planets beyond Our Solar System,

https://exoplanets.nasa.gov/alien-worlds/historic-timeline/#first-transiting-exoplanet-observed.

---. “Kepler-22 B - NASA Science.” Science.nasa.gov,

https://science.nasa.gov/exoplanet-catalog/kepler-22b/.