A new study suggests finding evidence of life on our planet could depend on the time of year the alien astronomers are looking. The new study could be a piece to getting there, looking at how the planet looks outside during the various seasons. There is so much going on here on our planet, and the new study does not even delve into clouds and their effects.
All we needed was to spot the telltale signs of life in the atmospheres of exoplanets, and we had a better idea of what these looked like here on our own planet. The good news is that by using telescopes, we can examine the planets' atmospheres, even when they are orbiting other stars. As the Earth moves closer in view of these exoplanets, astronomers are continuing to refine the tools they use to find and investigate planets beyond our galaxy.
Having narrowed the field down to the most promising planets, astronomers are aligning viewing times with the James Webb Space Telescope to survey their atmospheres, thinking about what signs of life we should be looking for once more -- and weighing up the prospects of success. Scientists are looking primarily at planets in the habitable zone, located within orbital distance from the host star, where the planet's temperature might allow liquid water on its surface. Some astronomers are looking for exoplanets that may favor life, narrowing the search to Earth-like planets in their star's habitable zones.
Since the 1950s, astronomers have proposed the habitable zones around stars are the most probable places for life to exist. Although astronomers have not probed those distances for Earth-like exoplanets, they are packed together by stars, and we already know of seven exoplanets located within a habitable zone around their stars -- an arrangement that favors life appearance.
Estimating that about 25% of stars are surrounded by potentially habitable, rocky exoplanets, Lisa Kaltenegger calculated the number of Earth-like worlds falling in these distances. Even given these criteria, and knowing the ideal size for a planet to support life is roughly one to 1.5 times that of the radius of Earth, billions of planets may exist around billions of stars. Even assuming only one of those billion stars has planets supporting life, that is roughly 6.25 billion life-supporting planetary systems in the Universe.
As of December 2022, there were 5,284 exoplanets identified in 3,899 systems, while the remaining Solar System planets and moons have the potential to harbor proto-life, such as microorganisms. We can access the surfaces and atmospheres of other worlds in our Solar System, which allows us to search for even microscopic, minute signs of biological activity, including the impressions left by ancient, now-extinct life forms. One of the most unthinkable discoveries was detecting life on a distant planet, light years from our own.
Revealed, it came after years of observations on an Earth-size planet. In a first for astronomers studying worlds beyond our solar system, data from the Hubble Space Telescope has revealed the presence of water vapor in the atmosphere of an Earth-size planet. Researchers had been hoping to detect water vapor in the atmosphere of more Earth-like planets, particularly those within their star's habitable zones. A More Earth-like Planet But those worlds are relatively small, making it exceptionally hard to observe their atmospheres.
Some of the seven smaller planets orbiting the star TRAPPIST-1, 12.6 parsecs (41 light-years) away from Earth, are thought to contain significant amounts of water on their surfaces2. TRAPPIST-1 is another star that hosts a planetary system that may be suited to supporting life and is approximately 40 light-years away from our Solar System. Some of the more promising candidates to harbor life are five worlds around star K2-384, about 270 light-years from Earth. Star K2-384 is about 270 light-years from Earth.
Alien hunters have focused mostly on Earth-like planets - a sensible starting point, considering our water-covered, rock-enveloped world is the only one we know of hosting life. The research team said that ocean planets seem to be incredibly abundant across the galaxy and may harbor microbes like extremophiles, which thrive in some of Earth's most hostile environments. These extremophiles, species that flourish outside of limits most life in our Solar System can tolerate, maybe counterparts for forms of life on planets that we consider too harsh to support life.
They live in the sour chemical pools of Yellowstone National Park, in the barren valleys of Antarctica, in the hyper-heated ocean floor vents, and belong to branches of life that broke off from our planet Earth billions of years ago. In new research, researchers have identified one of these alien world classes - ocean planets, whose sizes are as much as 2.5 times larger than Earth's, with vast liquid-water oceans under hydrogen-rich atmospheres.
In the heady early days after discovering the first exoplanets around an ordinary star in 1995, space agencies were drawing up plans for ambitious and costly missions to explore terrestrial twins that might harbor life. Once it became clear Earth was just a planet amongst innumerable bodies in the Universe, the theory of alien life began to gain prominence within the scientific community. Researchers were pining for a giant space telescope designed specifically to image Earth-like alien worlds--a newer iteration on the idea that was the basis for Nasas ill-fated Terrestrial Planet Finder.
They would be able to sample the light of an array of other planets, and astronomers are already dreaming about a space telescope that could make a planet-like picture of the planets that is at least as good as a planet's worst. To search for signs of life on the Earth-like planets surrounding sunlike stars, astronomers would likely need to directly sample their light to produce spectra or even a real-world image. Although the James Webb Space Telescope would still view distant planets as little more than glowing dots in a visual spectrum, its instruments would help exobiologists envision what the planet could look or feel like.
The James Webb Space Telescope, or similar spacecraft in the future, may be able to detect signs of atmospheres similar to those on our planet -- oxygen, carbon dioxide, methane. Because of determination, astronomers could find out some information about an exoplanet's atmosphere or surface composition, in effect measuring a particular color of light coming from a planet.
Researchers have found there is not one representative sample of the heat-emitting spectrum from our planet. The new research concludes that a dynamic, living planet such as the Earth cannot be characterized by a single thermal emissions spectrum. To find ways of allocating precious observational time, some scientists are proposing targeting planets thought to be as mixed as Earth is, with both oceans and land.
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