Scientists detect two water worlds 218 light years away

Context: According to a new study two alien planets about 218 light years away from Earth have found a twin in the ocean worlds of Europa and Enceladus — moons orbiting Jupiter and Saturn.

Highlights of the study:

• The exoplanets, Kepler-138 c and Kepler-138 d, are likely water worlds — a feature that scientists have theorised for a long time, the study published in the journal Nature Astronomy noted.
• They are also larger-scale versions of Enceladus (Saturn’s moon) and Europa (Jupiter’s moon), the findings predicted.
• The study reported that the Kepler- 138 c and d are made up of ingredients lighter than rock (rocky planets like Earth) but heavier than hydrogen or helium (gas-giant planets like Jupiter).
• The researchers also discovered a fourth planet in the Kepler planetary system: Kepler-138 e.

About Saturn:

• Saturn is the second largest planet of the solar system in mass and size and the sixth nearest planet in distance to the Sun.
• Saturn has an overall hazy yellow-brown appearance.
• Saturn’s atmosphere is composed mostly of molecular hydrogen and helium.
• Saturn has 83 moons with confirmed orbits that are not embedded in its rings.
• The moons of Saturn are numerous and diverse, ranging from tiny moonlets only tens of metres across to enormous Titan, which is larger than the planet Mercury.
• Saturn got its tilt due to gravitational interactions with its neighbour Neptune according to a well-known theory.
  • But the new study argues that Saturn is no longer under Neptune’s gravitational influence.
• Titan, which is Saturn’s largest satellite, may have been responsible, suggested observations from NASA’s Cassini spacecraft, which orbited Saturn from 2004-2017.
• Titan’s fast migration caused the planet to tilt further, reducing Neptune’s gravitational influence on Saturn.

About Jupiter:

• Jupiter is the biggest planet in our solar system. It has big storms like the Great Red Spot, which has been going for hundreds of years.
• Jupiter is a gas giant and doesn’t have a solid surface, but it may have a solid inner core about the size of Earth. Jupiter also has rings, but they’re too faint to see very well.
• It is made mostly of hydrogen and helium.
• Jupiter has a very thick atmosphere.
• Jupiter has 79 confirmed moons.
• Jupiter is the fifth planet from the Sun. That means Mars and Saturn are Jupiter’s neighboring planets.
• Jupiter has been known since ancient times because it can be seen without advanced telescopes.
• Jupiter has been visited or passed by several spacecraft, orbiters and probes, such as Pioneer 10 and 11, Voyager 1 and 2, Cassini, New Horizons, and Juno.

Source: DownToEarth

Previous Year Questions

Q.1) Which one of the following is a reason why astronomical distances are measured in light-years? (2021)

1. Distance among stellar bodies do not change
2. Gravity of stellar bodies does not change
3. Light always travels in straight line
4. Speed of light is always same

Q.2) Recently, scientists observed the merger of giant ‘blackholes’ billions of light-years away from the earth. What is the significance of this observation? (2019)

1. ‘Higgs boson particles’ were detected.
2. ‘Gravitational waves’ were detected.
3. Possibility of intergalactic space travel through ‘wormhole’ was confirmed.
4. It enabled the scientists to understand ‘singularity’.