This conference will address the science of planetary interiors by combining recent observations of exoplanets, advances in planetary orbital dynamics, and discoveries in experimental and theoretical high pressure science. An emphasis will be placed on planets with radii up to 2.5 times that of the Earth. Continua a leggere Physics of Exoplanets: From Earth-sized to Mini-Neptunes
Siamo soli nell’Universo? E’ una delle grandi domande a cui tenta di rispondere da sempre il genere umano. E più ne sappiamo e maggiore diventa la probabilità di credere che il nostro pianeta sia una sorta di posto unico e speciale nell’Universo dove esiste la vita. Nonostante ciò, molti scienziati ritengono che si tratti solo di una questione di tempo prima che saremo in grado di trovare forme di vita extraterrestre. Ma le modalità su dove e come potremo incontrare gli ET rimangono altamente incerte.
“We are going to find life in space in this century“, Dr. Seth Shostak, Senior Astronomer at the Search for Extra-Terrestrial Intelligence Institute (SETI) said emphatically European Commission Innovation Convention. “There are 150 billion galaxies other than our own, each with a few tens of billions of Earth-like planets. If this is the only place in the Universe where anything interesting happening then this is a miracle. And 500 years of astronomy has taught us that whenever you believe in a miracle, you’re probably wrong”. How will discover life in space? Dr. Shostak sees it as a ‘three-horse race’ which will probably be won over the next 25 years. We will either find it nearby, in microbial form, on Mars or one of the moons of Jupiter; we will find evidence for gases produced by living processes (for example photosynthesis) in the atmospheres of planets around other stars; or Dr. Shostak and his team at SETI will pick up signals from intelligent life via huge antennas. Dr. Suzanne Aigrain, Lecturer in Astrophysics at Oxford University, who studies extrasolar planets or exoplanets (planets around other stars than the Sun), represents horse number two in the race. Speaking at the Convention, Dr Aigrain noted that, based on her studies, she would also bet that we are not alone. “We are very close to being able to say with a good degree of certainty that planets like the Earth, what we call habitable planets, are quite common [in the Universe] … That’s why when asked if I believe there’s life on other planets, I raise my hand and I do so as a scientist because the balance of probability is overwhelmingly high“. Dr. Aigrain, and the groups that she works with, have so far been using light , electromagnetic radiation, as their primary tool to look for planets around stars other than the Sun. Habitable planets are defined as those that are roughly the size of the Earth where the surface temperature is suitable for liquid water to exist on the surface. The life ‘biomarkers‘ that Dr. Aigrain and her colleagues look for are trace gases in the atmospheres of the exoplanets that they think can only be there if they are being produced by a biological source like photosynthesis.
Dr. Shostak and SETI, meanwhile, seek evidence of life in the Universe by looking for some signature of its technology. If his team does discover radio transmissions from space, Dr. Shostak is quite certain that they will be coming from a civilisation more advanced than our own.
“Why do I insist that if we find ET, he/she/it will be more advanced than we are? The answer is that you’re not going to hear the Neanderthals. The Neanderthal Klingons are not building radio transmitters that will allow you to get in touch“. If we do find life on other planets or intercept a radio signal, what are the consequences? Finding a microbe that isn’t an earthly microbe will tell us a lot about biology, but there will also be huge philosophical consequences. In Dr. Shostak’s words, ‘It literally changes everything’.
E’ quanto afferma l’astrofisico René Heller del McMaster’s Origins Institute secondo il quale la vita extraterrestre potrebbe essere presente su un’altra categoria di pianeti molto diversi da quelli terrestri che non sarebbero, così, il posto ideale dove può emergere la vita, almeno come noi la conosciamo. Questi mondi alieni detti “super abitabili” avrebbero una massa due o tre volte superiore rispetto a quella del nostro pianeta e potrebbero essere decisamente più vecchi in termini di età.
“The Earth just scrapes the inner edge of the solar system’s habitable zone, the area in which temperatures allow Earth-like planets to have liquid surface water”, says Heller. “So from this perspective, Earth is only marginally habitable. That led us to ask: could there be more hospitable environments for life on terrestrial planets?” Heller and co-author John Armstrong of Weber State University describe superhabitable planets in a paper published in the journal Astrobiology. In it, they outline some of the characteristics such planets might have. They include many, shallower bodies of water (rather than a few large oceans), a more reliable global “thermostat” that impedes ice ages, and a magnetic shield, to protect the planet from cosmic radiation.
Heller says the theory means astronomers should be aiming their telescopes at planets that have so far not garnered much attention in the search for extraterrestrial life.
“We propose a shift in focus”, he says. “We want to prioritize future searches for inhabited planets. We’re saying ‘Don’t just focus on the most Earth-like planets if you really want to find life.’” But is the discussion about which planets to look at even worth having? How likely are we ever to find life on another planet? “Statistically speaking, I would say it’s very unlikely that there is nothing out there”, says Heller. “For the first time in history, we have the ability, both technical and intellectual, to find and classify potentially inhabited planets. It’s just a matter of how we spend our observation time”. Heller expects the paper to serve as a launching point for a debate about superhabitability. He says it may take some time for the scientific community to come around to the theory. “When you follow a certain pattern for decades, it can be hard to change your mind”.
McMaster University: Looking for life in all the wrong places arXiv: Superhabitable Worlds