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8th of June: Venus Transit

> A Rare Eclipse...

> ...Predicted by Johannes Kepler

> The Brightest Planet


dilluns, 7 de juny de 2004
On the 8th of June, an event referred to be scientists as the Venus transit occurred, a quite exceptional astronomic phenomenon, both because of its spectacular nature and the rarity of its occurrence. The phenomenon describes the passage of the planet Venus in front of the Sun, which happens when the Earth, Venus and the Sun are aligned.

The Venus transit could be seen from 75 % of the Earth's surface. The event, which lasted for over six hours, began at about 5:20 hours Greenwich Mean Time. This means that, in our country, the passage of Venus in front of the Sun started exactly two hours later, at 7:20, taking into account the time difference and the fact that we are in official summer time.

Those who didn't get a chance to see the Venus transit will have one last opportunity on the 6th of June 2012. The phenomenon occurs cyclically and in pairs: the time in the middle of each successive pair of transits is eight years, and from one pair to the next, just over one hundred years.

After 2012, there will be no other Venus transit until 2117. In fact, since the invention of the telescope in the seventeenth century, only six have been observed.
  • ! Actualització el 08/06/2004 a les 08:12
  • + Webs relacionades dins Nosaltres.Com: Astronomia

A Rare Eclipse...


+ The last Venus transit was in 1882.
In one way, the Venus transit could be classified as an eclipse. As you know, an eclipse is the concealment, either partial or total, of one star by another. The solar and lunar eclipses are among the most well-known. The former occurs when the Moon comes between the Sun and the Earth, which prevents us from seeing the disc of the Sun; and the latter happens because of the Earth coming between the Sun and the Moon, which has the effect of darkening our only satellite planet. Now, because Venus is much further from the Earth than the Moon is, the eclipse caused by this planet has a different effect to that caused by the Moon: instead of blocking our view of the Sun, as occurs in solar eclipses, the transit will allow us to see a small dark stain (Venus) moving across the Sun.

...Predicted by Johannes Kepler


+ Johannes Kepler was the first to predict a Venus transit.
The first scientist to predict a Venus transit was the German Johannes Kepler (1571-1630). This astronomer, a mathematical genius, was an assistant to the eminent Danish scientist Tycho Brahe, and basing himself on the latter's precise measurements, he conceived the laws of motion of the planets. Kepler established that the planets do not move in a circular pattern, but in an elliptical one, and he predicted that in 1631 a Venus transit would occur. And indeed, in 1631 the predicted transit did take place, and could be seen at dawn by people in Austria, Germany, Denmark and Italy, but not by Kepler himself, who had died a year before.

The Brightest Planet


+ Venus is the second planet closest to the Sun.
Venus, of all the planets in the Solar System, is the second closest to the Sun, after Mercury, and the brightest star in the sky after the Sun and the Moon; this most likely explains why it was given the name Venus, the goddess of beauty in Roman mythology. Venus is actually similar to the Earth in terms of size, mass, volume and density, but the surface temperature is much higher than that of the blue planet, as it can reach 480ºC. This is because of the density of the atmosphere, which causes an extremely intense greenhouse effect.

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  • Venus's rotational time, in other words, the time it takes to fully turn around itself, is unusually long: 243 days (that of the Earth is a single day).
  • As well as this, the planet is the only one in the whole Solar System on which the Sun rises in the West and sets in the East.
  • It is not only Venus that has a transit: Mercury does too. They occur on average thirteen times every century.
  • Although Johannes Kepler predicted the Venus transit of 1631, he did not do the same for that of 1639. This one was predicted by the Englishman Jeremiah Horrocks, a student of Kepler's work.

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> Els trànsits de Venus, des del 1631.
> L'anglès Jeremiah Horrocks fou el primer a observar un trànsit d'aquest planeta.
> Explicació de l'efecte de la gota negra.
> Característiques bàsiques del planeta més lluminós del firmament.
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