Luas Extrasolares

Enquanto os planetas extrasolares continuam a trazer surpresas, a procura vira-se agora também para possíveis luas extrasolares.
Os métodos de procura serão semelhantes.

No jornal Telegraph:
“Scientists at University College London believe there are thousands of habitable moons orbiting planets in other solar systems trillions of miles from our own. They have calculated that it should even be possible to spot these moons using a space telescope launched by Nasa earlier this year to hunt out other planets. (…) He claims there are more than 12,500 stars within sight of Nasa’s Kepler Space Telescope that have the potential for moons orbiting in areas of space where conditions could be favourable to life – the so called habitable zone. He and his colleagues have devised a new method for detecting moons in other solar systems – known as exomoons.”

No site da ESA (em 2003):
“ESA is now planning a mission that can detect moons around planets outside our Solar System, those orbiting other stars. (…) ESA plans to launch its ‘rocky planet’ finder Eddington. By detecting the drop in light seen when a world passes in front of its parent star, Eddington will be capable of discovering planets the size of Jupiter, and also those smaller than Mars. That means, if our own Solar System is anything to go by, it will be capable of detecting moons similar in size to Titan and the four large moons of Jupiter. It would be particularly exciting if such combinations of planets and moons were found orbiting a star at Earth’s distance from the Sun. Perhaps then the surfaces of the moons would be warmed to habitable levels.”

No site Extrasolar Visions:
“Extrasolar moons are just as speculative. But the example of Mercury and Venus does offer us limits. Given stellar tidal forces and slow rotation rates, planets close to their stars probably lack moons of any permanence. Hot Jupiters probably formed far from their stars and may have once had a retinue of moons, but these moons would have long ago been lost or destroyed as their parent world drifted closer to their star. Today, such Hot Jupiters may possess the occasional captured asteroid, but the orbits of such companions would be unstable and would eventually lead to their destruction. Just like their ancient predecessors, the captured moons would either break up within the planet’s Roche limit or impact the planet’s surface.
But what about those more distant planets that are lucky enough to retain a family of moons? What would they be like? Two factors can give us a clue. One is the mass of the planet. In general, a more massive planet will have the potential for more massive moons. Jupiter has four large moons that would easily qualify as planets in their own right if they were orbiting the sun directly. Saturn has a host of smaller moons and one large moon, Titan, that rivals the big moons of Jupiter. Uranus and Neptune both have smaller moons, but many of them are still massive enough to be spherical and one, Neptune’s Triton, is larger than Pluto. Given this sort of progression, it seems safe to assume that some of the more massive exoplanets might have moons as massive as Mars or even the Earth.
But this kind of speculation should be taken for what it is, speculation.”

No site do MSNBC:
“An extrasolar world might have multiple moons, as depicted in this illustration by John Whatmough. Scientists say there are probably a lot of the moons in the galaxy, and some might support life. (…)
Planets beyond our solar system are incredibly challenging to find. Moons are nearly impossible with today’s technology, given that they are generally expected to be quite small compared to their parent worlds. (…)
Finding moons is more than just an academic quest to count them up. Planetary satellites can be highly interesting in their own right.
It’s possible, for example, that life could exist on extrasolar moons, researchers say.
And it has been suggested that the ocean tides induced by Earth’s moon may have been necessary to create the conditions for life on our planet to begin. At the least, the evolution of life has been affected by our moon’s constant tugging.”

Softpedia:
“Until now, several hundred planets have been found orbiting around nearby stars while the number of moons remained at a constant zero. It’s not that they’re not there, it’s just that we can’t see them with today’s technology. To put it even simpler, the smallest planet ever found was a terrestrial one, at least three times the mass of the Earth, but finding a moon today is more like finding a specific molecule of water inside an ocean.”

Universe Today:
“The presence of exomoons can also be detected via the “wobble method”. Track an exoplanet during its orbit around a star to see its own wobble due to the gravitational interaction between the exoplanet/exomoon system. As if we needed any more convincing that this is not already an ‘all kinds of awesome’ project, Kipping has another motivation behind watching exoplanets wobble. He wants to find Earth-like exomoons with the potential for extraterrestrial life…”

(Recriação artística de um gigante gasoso com um satélite natural idêntico a Pandora)

Satélites Naturais capazes de albergar vida, como Pandora (Avatar) e Endor (Guerra das Estrelas) poderão ser potencialmente detectados, caso existam.
De acordo com Lisa Kaltenegger, do Harvard-Smithsonian Center of Astrophysics, “se Pandora existisse, poderíamos potencialmente detectá-la e estudar a sua atmosfera na próxima década”.
Leiam estes artigos: Space.com, Eternos Aprendizes.

O filme Avatar, por ser passado numa lua, relançou e de que maneira a discussão sobre potenciais lugares para a vida, com a comunidade científica agora a inclinar-se bastante para as grandes luas (potencialmente cheias de água) das centenas de Hot Jupiters que se vão descobrindo lá por fora.