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Constellations on the Internet

Eighty-Eight Constellations

The Constellations at Recerca en Acció

Google and Microsoft: Star Wars

dimarts, 27 de maig de 2008
Constellations are sections of the sky made up of a group of stars (celestial bodies that emit their own light) and the area that surrounds them. The groups are totally arbitrary because they are sometimes made up of stars that lie huge distances from one another. To find out about the origin of constellations, we have to go back to ancient times.

In Antiquity, the men of science realised that certain groups of stars formed patterns and associated these patterns with animals, objects, and mythological figures, etc. Towards the 2nd century AD, more than half of those that we recognise today had been described: the astronomer, geographer and mathematician Claudius Ptolemy described 48 in his 'Almagest'.

But, of course, the constellations recorded by Ptolemy only include those that were visible from the northern hemisphere. The world had to wait until Modernity, with its geographic discoveries and explorations to the southern hemisphere to complete the map of the sky.

In 1930, the International Astronomical Union (IAU) divided the celestial sphere into 88 constellations, fixing precise boundaries for each one.
  • + Webs relacionades dins Nosaltres.Cat: Astronomia.

Eighty-Eight Constellations

+ Constellation Aquarius is identified with the Trojan prince Ganymede.
Of these 88 constellations, some can only be seen from either the northern or the southern hemisphere. The twelve constellations of the zodiac, however, can be seen from both hemispheres. These twelve (plus Ophiuchus) are located along the ecliptic, the imaginary line that describes the trajectory of the sun during the 12 months of the year. Which is why, in Ancient times, the zodiac was divided into 12 parts, or signs: Aries, Taurus, Gemini, Cancer, Leo, Virgo, Libra, Scorpius, Sagittarius, Capricornus, Aquarius and Pisces.

The Constellations at Recerca en Acció

+ The graphic shows the visible constellations from Catalonia.
Depending on the time of year, we can see different constellations from the same place. This is due to the movement of the Earth around the Sun. The web portal Recerca en Acció recently published an interactive graphic feature allowing users to identify the main constellations that are visible from Catalonia in spring, summer, autumn and winter. Recerca en Acció also tells users how to tell the time by observing the stars.

Google and Microsoft: Star Wars

+ Google Sky was launched in August 2007.
Most people know that Google and Microsoft are two giants who are fighting it out to control the Internet. And not just here on Earth, but also in space! This month, Microsoft launched its WorldWide Telescope (WWT) programme, a virtual telescope allowing us to wander through 1.2 million galaxies. The programme, which can be downloaded free by Windows users, is Microsoft's answer to Google Sky, a similar service offered by Google that is also free but that does not need to be downloaded. Launched in August 2007, Google Sky also lets users take a virtual stroll through stars, constellations, planets, and galaxies, etc.



  • Due to the fact that stars move, constellations have not always looked the way they look today.
  • The first person to discover that stars move was the English astronomer Edmond Halley, who compiled the first catalogue of stars in the southern hemisphere.


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