Frozen World Could Be The Size Of Earth And May Be Habitable Once Red Stars Age, Study Says

The universe is consists of stars that vary in phases and ages. Planetary diversity believes that around other stars, initially frozen worlds could be the same size of Earth and may have habitable conditions once the star becomes older. Astronomers usually looked at middle-aged stars like our Sun, however in order to find habitable worlds, it is also important to look around stars of all ages, including the red giants.

According to Science Daily, the oldest detected Kepler planets, which are the exoplanets found using NASA's Kepler telescope, are about 11 billion years old. The Sun is believed to be 4.6 billion years old as of present time. It was also said that in their work, Ramses M. Ramirez, research associate at Cornell's Carl Sagan Institute and Lisa Kaltenegger, associate professor of astronomy and director of the Carl Sagan Institute, have shaped the location of the habitable areas for aging stars and how long planets can stay in it. The "habitable zone" is the region around a star in which water on a planet's surface is liquid and signs of life can be remotely detected by telescopes.

"When a star ages and brightens, the habitable zone moves outward and, you're basically giving a second wind to a planetary system," said Ramirez. "Currently, objects in these outer regions are frozen in our own solar system, and Europa and Enceladus - moons orbiting Jupiter and Saturn - are icy for now."

Planets and their moons can stay in this red giant habitable zone for up to 9 billion years depending on the weight of the original star. Earth, for example, has been in our Sun's habitable zone so far for about 4.5 billion years, and it has been abundant with changing repetition of life. However, in a few billion years, our Sun will become a red giant, engulfing Mercury and Venus, turning Earth and Mars into sizzling rocky planets and warming distant worlds like Jupiter, Saturn, and Neptune - and their moons - in a newly established red giant habitable zone.

"Long after our own plain yellow Sun expands to become a red giant star and turns Earth into a sizzling hot wasteland, there will still be regions in our solar system - and other solar systems as well - where life might thrive," said Kaltenegger. "For stars that are like our Sun, but older, such thawed planets could stay warm up to half a billion years in the red giant habitable zone. That's no small amount of time," said Ramirez

Astronomy has reported Kaltenegger saying, "In the far future, such worlds could become habitable around small red suns for billions of years, maybe even starting life, just like on Earth. That makes me very optimistic about the chances for life in the long run."