from Hacker News

Astronomers Detect a Possible Signature of Life on a Distant Planet

by julienchastang on 4/16/25, 11:20 PM with 128 comments

  • by philipkglass on 4/16/25, 11:42 PM

    This is about dimethyl sulfide in the atmosphere of exoplanet K2-18b:

    https://en.wikipedia.org/wiki/K2-18b

    The NYT article reports a new study in The Astrophysical Journal and links to it, but the DOI is currently not found:

    https://dx.doi.org/10.3847/2041-8213/adc1c8

    I also don't see the article yet under their Latest Articles:

    https://iopscience.iop.org/journal/0004-637X

    Here are recent articles about K2-18b from Google Scholar:

    https://scholar.google.com/scholar?hl=en&as_sdt=0,48&q=%22K2...

  • by pizza on 4/16/25, 11:32 PM

  • by belinder on 4/17/25, 12:04 AM

    If life evolves on a planet with only oceans, no surface, imagine how much longer it would take to discover rockets that can leave the planet.

    Like if there was no surface on earth, and only fish, there must be some very significant reason for advanced fish to even want to leave the water, let alone the atmosphere

  • by smitty1e on 4/16/25, 11:41 PM

    > While inspecting K2-18b, Dr. Madhusudhan and his colleagues discovered it had many of the molecules they had predicted a Hycean planet would possess. In 2023, they reported they had also detected faint hints of another molecule, and one of huge potential importance: dimethyl sulfide, which is made of sulfur, carbon, and hydrogen. On Earth, the only known source of dimethyl sulfide is life.

    ---

    Intriguing.

  • by jmyeet on 4/17/25, 1:25 AM

    This is your daily reminder that if we do indeed discover life so close (~120 LY) to Earth, it's an incredibly bad sign for us. This is an exercise in Bayesian reasoning.

    Imagine there are 2 planets in the Milky Way where life has developed. The odds are incredibly low they're next to each other, assuming a random distribution. So it's way more likely that there are more than 2. Imagine a sphere of radius 60 LY (120/2). Our Earth is the center of one. This planet is another. That's a volume of 10^6 LY^3. The Milky Way volume (from Google) is ~17T LY^3 so there'd be roughly 170M such spheres in our galaxy.

    Now imagine if the odds of simple life becoming intelligent life that we could detect and could become spacefaring is 1 in 1 million. There'd be ~170 such civilization in the Milk Way.

    We have absolutely no evidence of this So simple life is a lot less common, intelligent life is a lot less likely or, and this is the scary part, something tends to wipe out sentient civilizations and that's likely in our future.

    In Fermi Paradox terms, we call this a Great Filter.

  • by cheshire137 on 4/17/25, 1:42 AM

    Looking forward to the John Michael Godier video that he'll inevitably put out about this.

  • by wewewedxfgdf on 4/17/25, 3:35 AM

    It's never aliens.

  • by JoeAltmaier on 4/17/25, 12:41 AM

    Maybe look for signs of chemistry that indicates industry? Teflon, by-products of steel-making, plastics, something like that? Signs of intelligent(?) life.

  • by damnitbuilds on 4/17/25, 1:09 AM

    What now? How do we confirm or disprove life there?

    Existing telescopes?

    Or do we need to design one quick, for Starship to take up next year?

  • by ianpenney on 4/17/25, 6:09 AM

    The detection of dimethyl sulfide on an exoplanet is an exciting development, ok. And DMS on Earth is almost entirely biologically sourced, but that doesn’t make it an exclusive biosignature. There are plausible abiotic pathways for DMS formation, such as in geochemistry we can’t know entirely about because we live on earth.

    I’m not sure a journalist for this exalted American newspaper here knows anything about this and frankly the excited language of this article is dumb af. Probably because excited people keep paying for subscriptions to this trash.

    It took my amateur self nearly 10 mins to ask around to qualified friends and research some counter ideas.

  • by John7878781 on 4/16/25, 11:32 PM

    This is unsettling. If we are not the only intelligent beings in the universe, it adds credence to the idea of a "great filter."

    https://en.wikipedia.org/wiki/Great_Filter