{"id":61612,"date":"2024-07-27T07:22:00","date_gmt":"2024-07-27T07:22:00","guid":{"rendered":"http:\/\/8a26921a-b589-442b-8655-b0a618f26443"},"modified":"2024-07-27T07:39:42","modified_gmt":"2024-07-27T07:39:42","slug":"the-story-of-kepler-22b-the-first-exoplanet-discovered-orbiting-within-the-habitable-zone-of-its-host-star","status":"publish","type":"rss_feed","link":"https:\/\/c01.purpledshub.com\/bbcskyatnight\/rss_feed\/the-story-of-kepler-22b-the-first-exoplanet-discovered-orbiting-within-the-habitable-zone-of-its-host-star\/","title":{"rendered":"The story of Kepler-22b, the first exoplanet discovered orbiting within the habitable zone of its host star"},"content":{"rendered":"

<\/p>

By <\/p>

Published: Saturday, 27 July 2024 at 07:22 AM<\/p>

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Kepler-22b was the first exoplanet ever discovered lying inside its parent star\u2019s habitable zone.<\/p>

It was discovered by the now-retired Kepler Space Telescope and, at the time, was an incredible discovery.<\/p>

That was back in 2011, but the exoplanet<\/a> still represents one of our best chances of discovering live elsewhere in the Universe.<\/p>

Diagram showing how the Kepler-22 system compares with our own Solar System. Credit: NASA\/Ames\/JPL-Caltech<\/figcaption><\/figure>
A brief history of exoplanet science<\/strong><\/h2>
These days, of course, we take exoplanets for granted.<\/p>
With over 5,700 exoplanets<\/a> fully confirmed and thousands of other candidates awaiting further study, we talk glibly about what their atmospheres are like and whether they\u2019d be capable of supporting Earth-like lifeforms.<\/p>
Sometimes forgetting, perhaps, that the first confirmed exoplanet wasn\u2019t spotted until 1992, a mere 32 years ago.<\/p>
The existence of other planets had long been mooted, of course, but we had no concrete proof of their existence.<\/p>
For all we knew, the (then) nine planets of our own Solar System were the only ones in the entire Universe!<\/p>
It\u2019s crazy to think that an idea which seems risible now is actually what many of us (those of us aged over 45 or so, anyway) were taught in schools.<\/p>
$\"Artist's$
Artist’s impression of exoplanet Kepler-22b. Credit: NASA<\/figcaption><\/figure>
Kepler-22b discovery<\/strong><\/h2>
It’s fair to say that the 1992 discovery of a planetary system around the pulsar PSR B1257+12 caused quite a stir.<\/p>
Nearly two decades later, the discovery of Kepler-22b would have an equally big impact, due to its \u2018Goldilocks\u2019 location.<\/p>
Very simply, if a planet\u2019s too close to its parent star, it\u2019s too hot for life to exist because water (an essential component of life as we currently understand it ) would boil away; if it\u2019s too far away, it\u2019s too cold and water would freeze.<\/p>
In-between those two extremes lies the \u2018Goldilocks\u2019 or habitable zone, where it\u2019s neither too hot nor too cold.<\/p>
And it was in the habitable region around the Sun-like star Kepler-22 that, in December 2011, astronomers\u00a0 spotted a planet whose radius is just 2.1 times that of our own Earth, putting the planet in the \u2018super-Earth\u2019 category, much like Kepler-452b<\/a>.<\/p>
$\"Artist's$
Artist’s impression of Kepler-452b. Credit: NASA Ames\/JPL-CalTech\/R. Hurt<\/figcaption><\/figure>
Is Kepler-22b a habitable planet?<\/strong><\/h2>
Given that Saturn, for instance, has a radius that\u2019s 9.5 times that of Earth, that makes Kepler-22b \u2013 a roughly Earth-sized planet, orbiting a Sun-like star at an orbital distance that puts it within the star\u2019s habitable zone \u2013 about as Earth-like an exoplanet as science has turned up so far.<\/p>
Kepler 22-b lies about 15% closer to its parent star than Earth does to the Sun, which would make it significantly hotter, were it not balanced out by the fact that host star Kepler-22 shines 25% less brightly than the Sun.<\/p>
Scientists believe Kepler-22b to be a \u2018water world\u2019 similar to the exoplanet Gliese 1214 b, with substantial quantities of water in the form of surface oceans.<\/p>
In that case, life could well be present in such oceans \u2013 though other astronomers have suggested Kepler-22b could instead be a \u2018gas dwarf\u2019 similar to exoplanet Kepler-11f.<\/p> <\/body><\/html>\n
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