VilaWeb - Diari escola: Discovered: The Farthest Galaxy

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divendres, 27 de desembre de 2024

> What is a Galaxy?

> The Galaxy and the Milky Way

> The Hubble Space Telescope

dimarts, 24 de febrer de 2004

On the 15th of February an international team of astronomers discovered the farthest galaxy in the Universe: so far that it is situated 13,000 million light years from Earth.

The pictures of this galaxy were taken by the Hubble space telescope and then confirmed by the Keck Observatory in Hawaii, and they correspond to the moment at which the galaxy, and also the Universe, were 750 million years old, 5% of their current age, when the Universe was just coming out of what is known as the dark age and did not yet have shining stars.

But how could the scientists know that the galaxy is 750 million years old? Basically, for two reasons. Firstly, because the picture of this galaxy has never reached us until now, so the light that it emits has been travelling for 13,000 million years before it arrived at our planet. Secondly, because the Universe began just over 13,700 million years ago, when a huge explosion occurred, which is known as the Big Bang. So, it's just a matter of a simple subtraction.

The fact is that the discovery of this new galaxy will allow scientists to penetrate the mystery of what the galaxies that gave rise to the stars of today were like, all those millions of years ago.

+ Webs relacionades dins Nosaltres.Com: Astronomia

What is a Galaxy?

+ Galaxies can be elliptical, irregular and spiral.

Galaxies are enormous groups of stars, and because stars emit light, when we look through the telescope, they appear shiny, but also nebulous and dull at the same time. In fact, depending on their appearance, galaxies can be elliptical, irregular (without any symmetry that marks them) and spiral. The latter are the most common, and make up 80% of them. Galaxies were caused by the Big Bang when, because of condensation, they formed the first galactic stars. It is also at the centre of galaxies where there is the greatest concentration of stars, which explains why this area, known as the galactic disc, is perceived to have greater luminosity.

The Galaxy and the Milky Way

+ The Galaxy contains around 100,000 million stars.

The Milky Way is a bright band across the sky made up of many stars, although it is not exactly a galaxy, even if people say that it is the galaxy to which our Solar System belongs. In fact, our galaxy is called the Galaxy and the Milky Way is the area within this galaxy in which the greatest number of stars is concentrated. Our Galaxy contains around 100,000 million stars, it is of the spiral type and made up of five arms, one of which holds the Sun, at a distance of 27,000 light years from the galactic centre. The Sun, and by extension the entire Solar System, revolves around this centre at an average speed of 220 Km/s, completing a revolution every 200 million years.

The Hubble Space Telescope

+ The pictures of the the farthest galaxy were taken by the Hubble telescope.

We were just saying that the pictures of the farthest galaxy ever identified were taken by the Hubble space telescope. This telescope, 2.4 metres in diameter, forms part of the Hubble Observatory, which has been orbiting the Earth since 1990. It is the only telescope that man has launched into space, with the aim of probing the secrets hidden in the Universe. In the middle of February, the North American Space Agency (NASA) announced its decision to cancel the missions that provide maintenance for Hubble and allow it to gradually be abandoned, although soon after this decision was reconsidered. Many scientists hope that the recent discovery by the telescope will lead NASA to keep it operative.

MATERIALS

Telescopi Hubble
Format:Web
Web oficial del Hubble, amb informació del telescopi i una colla d'activitats i jocs relatius a fenòmens diversos de l'Univers.
Materials d'astronomia
Format:Web
Materials didàctics per a l'aprenentatge de l'astronomia.
Imatges de galàxies
Format:Web
Galeria fotogràfica de galàxies.
Què hi ha a l'Univers?
Format:Web
Unitat didàctica de l'edu365 sobre l'Univers.
Astronomia Educativa
Format:Web
Espai dedicat al Sistema Solar i a l'Univers que s'adreça a escolars d'ensenyament primari i secundari.
Explorant l'Univers
Format:Web
Pàgina de notícies de l'Agència Espacial Nord-americana (NASA).
StarChild
Format:Web
Web adreçada a joves afeccionats a la ciència astronòmica.

QUE HO SABIES?

The Milky Way can be seen by the naked eye on a clear night, but one needs to get far away from any cities, where light pollution stops us from seeing it.
The Hubble telescope owes its name to the North American astronomer Edwin Powell Hubble (1889-1953), the first man to prove the existence of galaxies beyond our own Galaxy, and he also categorised them as spiral, irregular and elliptical and even studied their velocity.
If you think about it, the pictures of the galaxy identified by the Hubble telescope are 13,000 million years old. We owe the fact that we can 'see the past' to the eminent German physicist of Jewish origin, Albert Einstein, who in 1916 formulated the famous Theory of Relativity
In mid-February, a group of scientists discovered a gigantic diamond situated 50 light years from Earth, 2,500 km in diameter and located at the core of a star that has gone out. A diamond that, if you could buy it, would have a truly astronomical price!