2011-09-21 23:53:58
Times of schools, teachers and planets
When I went to school (yes, it was called “school” then), I had to learn the names of the 9 known planets. According to what my teacher (they were called “teachers” then) told me, the last of the planets, Pluto, was a newcomer, it had been discovered in that same century, in 1930. Of course I learned the string of names by heart and Even today, when we have changed the century and we no longer talk about schools and teachers, I still remember them as I learned them, even though the list of planets is no longer the same since Pluto was demoted to the category of “dwarf planet.” .
In those days, I must admit, things were easier than now. The world seemed forever organized by the two superpowers in discord and the heavens seemed undisturbed, except for those few planets with their satellites and comets in continuous but predictable motion. Then the unforeseen happened. The world remained discordant, but more disorganized, and the heavens were shaken by an earthquake of new discoveries.
First exoplanet, first surprise
It was in 1995, when the peace of the planetary family was disturbed by an unexpected discovery. In September of that year, astronomers Mayor and Queloz discovered a planet that revolves around the star 51 Pegasi. By then I was already old and I thought that, from that moment on, the textbooks would have to be corrected. I imagined the students reciting: “In the Universe there are two known planetary systems, one is the Solar system with 9 (now 8) planets and another, the 51 Pegasi system, with one.” The events that followed showed me how wrong I was.
Regarding the newly discovered planet, the little data that the researchers gave about it left me speechless. That distant world takes only four days to make a complete revolution around its star and rotates so close to it that the outermost layers must be baking at 1,300ºC. Accustomed as we are to the planet closest to the Sun, Mercury, being so small – some of Jupiter’s satellites exceed it in size – we tended to think that, if there were planets beyond, they should be organized in the same way. Big mistake, 51 Pegasi b It is neither rocky nor small like Mercury, quite the opposite, it is a huge gaseous planet with a mass twice that of Saturn. Such a planet in the vicinity of the Sun would cross the white sphere of the Sun every two days, an eclipse worth seeing.
The number of worlds grows
But, as I say, that was just the beginning. During the following years, the extrasolar planets grew like mushrooms, their number increased so much that, as of today, September 20, 2011, the existence of 685 has been demonstrated and there are more than a thousand on the waiting list to be confirmed. Remembering them will not be easy because each of them has an incomprehensible name, a mixture of numbers and letters: HD 118203 b, WASP-38 b, Kepler-11 c, etc. There will no longer be anyone capable of naming all the known planets at once.
The great diversity of worlds
The abundance of planets is overwhelming but, more than the quantity, what is surprising is the variety. There are gas giants, enormous balls of hydrogen and helium, much larger than Jupiter, there are light planets, loaded with ice, with a density so low that, if there were an ocean capable of housing them, they would float on the water like immense spherical boats; There are also dense and heavy planets, although so far our instruments are unable to discover whether, as expected, there are some Earth-like or smaller ones.
Depending on the shape and orientation of their orbits, there is also something to give and take: some follow almost circular orbits, as happens with the planets of the Solar System and others describe orbits so elongated that they oscillate between the torrid passage through the vicinity of the star and the icy solitude of the places furthest from it. In the Solar System, the planets move approximately in the same plane, the ecliptic, in other stars the planets move in different planes, there are no defined rules. Although planets the size of Earth have not been detected, there is no technology for this, some larger ones have been detected that could be rocky like it and move in areas suitable for the existence of liquid water. Perhaps, life is lurking in one of them waiting to hit our already sore ego.
The Sun is a solitary star but in our Galaxy there are many systems with doubles and triples, even with a greater number of stars. Planets have also been detected in some of these multiple systems. They are planets in whose sky more than one Sun shines. There is also the opposite case, that is, wandering planets not linked to any star. In short, there is such a variety and quantity of them that we can rightly speak of a true planetary zoo.
Our guest, David Barrado-Navascués, astrophysicist and director of the Hispano-German observatory of Calar Alto, is our guide in the “Planet Zoo.”
OTHER RELATED PROGRAMS
Extrasolar planets and star models. We spoke with Antonio Claret.
Storms in planetary atmospheres. Interview with Agustín Sánchez Lavega.
Could life exist based on silicon? We spoke with Jorge Laborda.
Wandering Planets
#Cienciaes.com #Zoo #planets #spoke #David #Barrado