Astronomers searching for extraterrestrial life have generally been focusing on trying to find Earthlike planets—small, rocky planets with breathable atmospheres and moderate temperatures. But a new study advocates revising the definition of a habitable planet to include the possibility of many more.

Astrophysicist Nikku Madhusudhan of the U. of Cambridge and colleagues have proposed searching for a new category of planet—those which could be much larger than Earth and much farther from their stars.

These hypothetical planets would have a global liquid-water ocean under a thick hydrogen-rich atmosphere. Madhusudhan calls them “Hycean” planets, a term combing “hydrogen” and “ocean.” They could be almost any distance from any star.

“We want to expand beyond our fixated paradigm so far on Earthlike planets,” Madhusudhan says. “Everything we’ve learned about exoplanets so far is extremely diverse. Why restrict ourselves when it comes to life?”

Hycean planets would have advantages over rocky planets when it comes to those which might be habitable, beginning with the belief there are many more Hycean planets than Earthlike planets. Also, being larger, they would be easier to examine for biosignatures (molecular signs of life). That would increase the odds of finding extraterrestrial life.

Astronomer Laura Kreidberg of the Max Planck Institute for Astronomy in Germanydoesn’t sound as optimistic. Hycean planets would have cloudy atmospheres, making it more difficult to discover biosignatures. And she says there is no evidence they really exist.

“It is a really fun idea,” she says. “But is it just a fun idea, or does it match up with reality? I think we absolutely don’t know yet.”

Astronomers Noah Tuchow and Jason Wright of Penn State University are actually going the opposite direction as Madhusudhan by seemingly reducing the number of habitable planets. They say planets can move into and out of the habitable zones over time.

“If you just look at a planet in the habitable zone in the present day, you have no idea how long it’s been there,” Tuchow says.It’s debatable whether or not a planet entering a habitable zone later in life could ever become habitable.

Comment: This story suggests to me that some astronomers are getting desperate in their efforts to find life in space. It’s similar to a hungry person going into the kitchen and not finding any normal food in the fridge or the pantry and considering eating the silverware or dinner plates instead.

The Cambridge scientists seem to be saying warmth from a sun or star or possibly oxygen either aren’tnecessary for life. But why stop there? By using our imaginations, maybe we could conceive of life without any atmosphere at all, without water, or even without a planet—free-floating cellsof life in space which somehow make use of cosmic radiation to maintain their existence.

Now I am being sarcastic, but it is no laughing matter that these scientists are completely ignoring the only absolute requirement for life, namely an intelligent Creator. “The fool says in his heart, ‘There is no God’” (Psalm 14:1).

Actually, the Cambridge scientists are in a way closer to the truth than what they realize. The only extraterrestrial world we know of with life doesn’t need heat from a sun because it has the Son. “The city (heaven)does not need the sun or the moon to shine on it, because the glory of God has given it light, and the Lamb is its lamp” (Revelation 21:23).

By Warren Krug

Reference: Lisa Grossman, “New ideas on what makes a planet habitable could reshape the search for life,” Science News [August 30,2021]

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QUESTION OF THE DAY

Which animal exhibits the strongest force?

The red kangaroo can kick with a force up to 759 lbs or 3,376 newtons. Dingoes and other potential predators know to avoid this champion boxer.

Source: John Upchurch, “Animal Olympics,” Answers [July-September, 2021], page 58

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