Lands of Heaven: a planet covered by a webcast unpublished
Next Saturday, February 13, 2009, the extra-solar planet XO-3b transits in front of the star around which it rotates. The phenomenon itself is not anything spectacular, as the planet in question completes a full orbit of its parent star in less than four days. On our planet, however, the event will be accompanied by disclosure of an initiative without precedent: for the first time ever, a professional telescope will observe the transit of the planet and broadcast live on the web.
The project is called "Land of the Sky" and borrows its name from the title of a book by Camille Flammarion, astronomer and popularizer French lived at the turn of the nineteenth and twentieth century. Obviously, the "land" or planets, referred to by Flammarion in 1877 were those that revolve around the Sun, the only known at the time. Only in 1995, in fact, dates from the discovery of the first of more than 400 currently known planets orbiting other stars.
Most of the planets belonging to this group, including XO-3b, the protagonist of the event on Saturday, have been detected indirectly, or through observations of the effects they produce on the properties of their parent stars. Because of the huge difference between the amount of light emitted by a star and very little light reflected by a planet, it is extremely difficult to directly observe a planet outside the solar ones immortalized so far can be counted on the fingers of one hand.
The transit technique, highly intuitive, is one of the most effective indirect methods to reveal the existence of a planet around a star: it is based on the fact that, when the planet during its orbit, is interposed between the star and us, it obscures the light. The parent star is thus less bright than usual, the distinctive sign of the presence of one or more planets in his court. Even if Saturday will therefore not be possible to "see" XO-3b as it passes in front of its parent star, you can admire Live the brightness of the star while shooting, and then again increases during the transit of the planet, or what astronomers call a "light curve" for a period of about three hours.
The decision to broadcast live online its light curve, one of the tools actually used by researchers in this field, is particularly happy, because it involves the public in the activity of specific contemporary astronomers, showing that This is certainly a romantics absorbed in the contemplation of the firmament, but modern scientists who, by accounts, analysis and graphs of various kinds, try to understand what happens in the rest of the universe.
The planet XO-3b, discovered in 2007, is very different from Earth, being a gas giant with a mass of about 12 times that of Jupiter, the largest in the Solar System. The star around which orbits, XO-3, is slightly larger than the Sun and is about 850 light-years away in the constellation of the Giraffe, to observe this star, too faint to be visible to the naked eye, it is necessary to obtain a small telescope.
To enable this novel will direct the telescope Ruths Observatory of Brera, Merate, near Milan, with a mirror of 134 cm in diameter, to be joined by even the telescope Observatory of Palermo and many other, smaller amateur telescopes. The event will be broadcast live on the site www.crabnebula.it and will be accompanied by comments and explanations of astronomers in Italian, English and Chinese. Thanks to this international touch, the organizers hope to involve the public in this observation "tour" of the passage of another world in the sky.
CLAUDIA MIGNONE
In the images, an illustration of the transit of a Jupiter-like planet in front of a star slightly larger than our sun (ESO) and an animation that shows how the curve evolves light of a star during the transit of a planet (crabnebula.it).
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