K2-18b – Recently Discovered Earth-like Planet

This article has been just updated: December 28th, 2019



K2-18b or Earth-like Planet is eight times the mass of the Earth and twice the size of the Earth. The distance of K2-18b is 110 light-years from the Earth too far to send a probe. Today’s technology is feeble to take photos from such distant worlds. They are too far away to send probes too. It is only the exoplanet that is known to have both water and temperatures that could be potentially habitable.

In the atmosphere of a rocky planet orbiting in the habitable zone of a star, water vapor is detected. (the region that is neither too close nor too far from the star, possibly for the planets to have liquid, surface water ). Outside the solar system, the only known exoplanet Earth-like planet i.e. K2-18b.

K2-18b - Recently Discovered Earth-like Planet

Related Article: 10 Earth-like planets could be our next home

The Earth-like planet having the correct temperature to support water has an atmosphere, has water in it. Its atmosphere was studied by astronomers at the University College London. According to astronomers, this exoplanet is the best candidate for habitability known till now.

The habitable zone is the region around the star where temperatures are considered sufficiently benign for water to exist in liquid form on the surface of the planet. K218b, also known as EPIC 201912552 b.


The exoplanet, known as K2-18b discovered in 2015. The Kepler Space Telescope observed its silhouette crossing between us and its star once every 33 days. Putting it just the right distance from its dim sun to receive about the same amount of solar energy as Earth. Hubble Space Telescope discovered water in the exoplanet.

However, it is uncertain how much water is present. Because simply detecting it stretched the Hubble’s abilities to their limit. Water present in the exoplanet could be between 0.01% to 50% of the total atmosphere. Humans would not fare well on the planet. If it has a hard surface, it would be hard to stand with gravity so much stronger than on Earth.



Planet K, Earth-like planet orbits an M-type star, mass is 8.92 Earths. It takes 32.9 days to complete one orbit of its star and is 0.1429 AU from its star. The Radius of the planet is 0.211 x Jupiter. However, its temperature is uncertain. Tsiaras team estimated a surface temperature between minus 100 and 116 degree Fahrenheit (minus 73 to 47 degrees Celsius).

The surface could on average colder than Antartica or hotter than Earths most blistering deserts. K2-18b seems considerably most hospitable. However, Planet K is not Earth 2.0.

The gravitational pull of the Earth-like planet is better understood as the mass and diameter are known. The combination of diameter and mass put the planet in the category of super-Earths – bigger than our comparatively small world smaller than gas giants planets example Jupiter and Neptune.

The presence of zippy orbit is also a problem to start a life. In addition, its sun is not a hot yellow star like ours. But a smaller cooler, a red dwarf. This is not the first time water has been detected in the atmosphere of the exoplanet. In addition, the previous candidates have has extremely hostile environments like a Saturn-like Behemoth with scorching surface temperatures.


  • It is an Earth-like planet eight times the mass and twice the size of the Earth.
  • K2-18b was first discovered in 2015 by Kepler Space Telescope.
  • The planet orbits an M-type star that produces far less heat than the sun.
  • It is located about 110 light-years about 650 million miles from Earth.
  • The Earth-like planet is a lot closer to its sun than our Earth from the sun. It only takes 33 days to transit.
  • The only Earth-like planet outside the solar system known to have the correct temperature, an atmosphere, and water.
  • K2-18b is a super-Earth putting its size between Earth’s and Neptune.


Hubble’s space telescope analyzed the data of K2-18b‘s atmosphere. In this analysis, the scientists also found atmospheric Hydrogen and Helium. The belief is that Nitrogen and Methane are also present. Further studies also needed to confirm it. Scientists also need to figure out how cloudy the atmosphere is and how much water vapor there is, percentage-wise. It is likely that there are water clouds in the K2-18b atmosphere and even possible rain.

However, the current studies suggest that K2-18b receives the same amount of radiation from its star as Earth receives from the sun. The previous study said that the exoplanet is either a rocky planet with a small gaseous atmosphere- like Earth, but bigger with a thick layer of ice mostly a watery planet.


  • Planets beyond our solar system are exoplanets.
  • More than 4000 exoplanets are detected until now but we don’t know much about their composition and nature.
  • Many giant planets are found.
  • More than 22 percent of the sun-like stars have Earth-sized planets in their habitable zones.
  • The Kepler MIssion was launched to search out distant worlds.
  • Types of an exoplanet Earth-like planet, Earth-size, Super-Jupiters, Gas-giants, rocky planets, Gas-dwarfs, etc.


Earth-like Planet

It is the world’s first space-based optical telescope that was launched into low Earth orbit in 1990. It has been named after astronomer Edwin Hubble. Hubble’s Telescope discovered water in the Earth-like planet K2-18b.

The team analyzed measurements of starlight from the red dwarf as the planet wandered across its face on eight separate occasions. According to the data K2-18b crossed in front of its star, wavelengths of light that are absorbed by water suddenly dropped off. And rose again as the exoplanet K2-18b moved on.

In the planet’s atmosphere, the effect is seen as a smoking gun for water vapor. However, the team detected a strong signature of water vapor. It means, first of all, there is an atmosphere and the second is water present in it. The discovery of water vapor in the exoplanet doesn’t prove that it contains water in it.

It is one of the NASA’S great observatories. NASA’s series of great observatories satellites are four large, powerful space-based astronomical telescopes.


Earth-like Planet

It was an observatory in space launched by NASA to discover Earth-size planets orbiting other stars. Therefore, it was launched in 2009 and decommissioned in 2018.

Future space missions are expected to detect hundreds more in the coming decades. Kepler and other telescope have been finding exoplanets by the thousands in recent years. Many of these are Super-Earths like K2-18b.

Results from the Kepler’s satellite mission, which discovered nearly 2\3 of all known exoplanets to date. It indicates that 5 % to 20% Earths and Super-Earths are located in the habitable zone.


So many new Super-Earths are expected to be found over a couple of decades. It is the first discovery of many potentially habitable planets. Scientists currently believe that the gaseous envelope of K2-18b likely prevents life. As we know it from existing on the planet’s surface. By studying these exoplanets which are in the habitable zone and having liquid present in it. Astronomers are one step closer to directly detecting signs of life beyond our solar system


Exoplanets |Definition, Properties, and Facts


1 thought on “K2-18b – Recently Discovered Earth-like Planet”

  1. For the first time, beyond our solar system astronomer have found water vapors and clouds in the atmosphere of an exoplanet K2-18 b where the temperature may be perfect for life.


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