Might a tyrannosaur roam on Trappist-1e, a protoceratops on Proxima Centauri b, or a quetzalcoatlus on Kepler 1047c? “Hopefully, we’ll find some planets that happen to have more oxygen than Earth right now because that will make the search for life just a little bit easier,” Kaltenegger said. “And who knows, maybe there are other dinosaurs waiting to be found.”

How close can a rocky planet be to a star, and still sustain water and life? A recently discovered exoplanet may be key to solving that mystery, providing important insights about conditions at the inner edge of a star’s habitable zone and why Earth and Venus developed so differently, according to new research led by Lisa Kaltenegger, director of the Carl Sagan Institute and professor of astronomy in the College of Arts and Sciences. “We don’t know what this planet on the edge of habitability could be like, so we have to look,” she said. “This is what real exploration is about.”

We are assembling the tools to search for life in the universe, so as not to miss it, taking all of Earth’s vibrant biosphere into account – even those in the breathtaking chilled places of our Pale Blue Dot. As ground-based and space telescopes get larger and can probe the atmosphere of rocky exoplanets, astronomers need a color-coded guide to compare them and their moons to vibrant, tinted biological microbes on Earth, which may dominate frozen worlds that circle different stars. But researchers need to know what microbes that live in frigid places on Earth look like before they can spot them elsewhere. The study, “Color Catalogue of Life in Ice: Surface Biosignatures on Icy Worlds,” published March 15 2022 in the journal Astrobiology, provides this toolkit. (story by Blaine Friedlander)

Using our own Earth as the key, we modeled five distinct Earth epochs to provide a template for how we can characterize a potential exo-Earth – from a young, prebiotic Earth to our modern world. The models also allow us to explore at what point in Earth’s evolution a distant observer could identify life on the universe’s ‘pale blue dots’ and other worlds like them. We created atmospheric models that match the Earth of 3.9 billion years ago, a prebiotic Earth, when carbon dioxide densely cloaked the young planet. Our Earth and the air we breathe have changed drastically since Earth formed 4.5 billions years ago, and for the first time, this paper addresses how astronomers trying to find worlds like ours, could spot young to modern Earth-like planets in transit, using our own Earth’s history as a template. (story by Blaine Friedlander, Cornell)

Seen from where would we be the aliens? And because stars move in our dynamic cosmos, this vantage point is gained and lost. 1,715 star-systems could have spotted Earth since human civilization blossomed about 5,000 years ago, and 319 more star-systems that will be added over the next 5,000 years. Exoplanets around these nearby stars have a cosmic front-row seat to see if Earth holds life, the scientists said in research published June 23 2021 in Nature (story by Blaine Friedlander, Cornell).

Astronomers seeking life on distant planets may want to go for the glow. Harsh ultraviolet radiation flares from red suns, once thought to destroy surface life on planets, might help uncover hidden biospheres. Their radiation could trigger a protective glow from life on exoplanets called biofluorescence. “Biofluorescent Worlds II: Biological Fluorescence Induced by Stellar UV Flares, a New Temporal Biosignature” was published in Monthly Notices of the Royal Astronomical Society.

If an alien had used color to observe if our Earth had life, that alien would see very different colors throughout our planet’s history – going back billions of years – when different life forms dominated Earth’s surface,” Kaltenegger said.
The research paper “Expanding the Timeline for Earth’s Photosynthetic Red Edge Biosignature” was in the Astrophysical Journal Letters.