It seems that whenever we have a fact about exoplanets nailed down, an exception will quickly crop up. The authors of today’s paper claim to have spotted a planet over twice the diameter of the Earth, made from solid rock.
In around five billion years, the hydrogen fuel in the core of the Sun will run out, and our star will begin to die. After swelling up into a red giant, many times bigger than its current size, the Sun will blow away its outer layers to leave a tiny, ultra-dense core, around the size of the Earth. White dwarfs, as these dead, slowly cooling star cores are known, are the ultimate fate for the vast majority of stars in the Universe.
Last month Nasa announced, in what seems like a roughly annual event, the discovery of “Earth 2.0”. Described as a “Bigger, Older Cousin to Earth”, Kepler 452b is the first small planet (defined here as less than twice the radius of the Earth) to be in a roughly one year orbit around a Sun-like star.
But is it otherwise that similar to the Earth? Is it potentially habitable? To try and answer that, let’s look at the discovery paper.
Of the more than 1500 exoplanets discovered over the past two decades, perhaps the most intriguing and unexpected have been the ultra-short period planets, worlds so close to their parent star that they complete an entire orbit in less than a day. Most are small, less than twice the radius of the Earth, and are so hot that their rocky crusts are being melted away. The debris could be used to investigate the composition of these mysterious worlds, but most of them are too small for our current instruments to observe in detail.
Hot Jupiters are weird and lonely. Is gravitational perturbation to blame?
Calling undergrads, graduate students and early career scientists interested in exoplanet studies and/or astrobiology to apply for the Emerging Researchers in Exoplanet Science Symposium and/or the Astrobiology Graduate Conference.