If a distant bright spot, for example, a quasar, is observed when a large mass interposes between it and the observer, the deviation of the light rays generates a lens effect. This phenomenon is known as "gravitational lens". The result is that, just as with an optical lens, the light is focused and the object looks brighter.
The constellations The stars that can be observed on a clear night form certain figures that we call "constellations", and that serve to more easily locate the position of the stars. In total, there are 88 groups of stars that appear in the celestial sphere and that take their name from religious or mythological figures, animals or objects.
Cosmology How and where does Cosmology come from? The human being has always been interested in knowing and understanding the Universe in which he lives and the laws that govern him. From different points of view, Philosophy, Religion and Science have tried to answer these questions. The Science that studies the Universe as a whole is called Cosmology or, also, philosophy of nature.
Black holes The so-called black holes are places with a very large, huge gravitational field. No electromagnetic or light radiation can escape, so they are black. They are surrounded by a spherical border called the "event horizon" that allows light to enter, but not out.
Gravitational waves Some equations formulated by Einstein in 1915 predicted the existence of a phenomenon called gravitational waves. At the end of 2015 these waves were detected directly. We all know what the waves are. For example, those that form in a pond with still water when a stone is thrown.
Quasars Quasars are distant objects that emit large amounts of energy, with radiations similar to those of the stars. Quasars are hundreds of billions of times brighter than stars. Possibly, they are black holes that emit intense radiation when they capture stars or interstellar gas.
Visible stars M-Z Markab: Star a of the constellation Perseus, belonging to spectral type A and whose magnitude has a value of 2.6. Menkar: Star of the constellation of the Whale, which has a magnitude 2 and forms a triangular figure with Aldebaran and Rigel. Mira Ceti: Star of spectral type M, belonging to the constellation of the Whale.
Visible stars A-L Alcor: Little bright star belonging to the Big Dipper, which forms, together with Mizar, a double system visible to the naked eye. Aldebaran: Star a of the constellation of Taurus which, with an apparent magnitude of 1.1, is one of the brightest in the sky. Also known as the eye or heart of the Bull, it is 53 light years from Earth and has a luminosity 90 times higher than that of the Sun.
Pulsars Pulsars are sources of radio waves that vibrate with regular periods. They are detected by radio telescopes. The word Pulsar is an acronym for "pulsating radio source", a pulsating radio source. Clocks of extraordinary precision are required to detect rhythm changes, and only in some cases.
Star Classification The photographic study of the star spectra was initiated in 1885 by astronomer Edward Pickering at the Harvard College observatory and concluded by his colleague Annie J. Cannon. This investigation led to the discovery that the spectra of the stars are arranged in a continuous sequence, according to the intensity of certain absorption lines.
How is the Milky Way? If we could observe the Milky Way from outside it, we would see the bulky center, yellow and bright, shaped like a rugby ball, and a thin bluish disc spinning around. Our galaxy has a spiral barred shape, like a grinder. In the center of our galaxy there is a black hole, which scientists call Sagittarius A.
Stars of the Universe Stars are masses of gases, mainly hydrogen and helium, that emit light. They are at very high temperatures. Inside there are nuclear reactions. The Sun is a star that we have very, very close. We see the other stars as very small luminous points, and only at night, because they are at great distances from us.
The laws of the Universe No one has imposed them, but the Universe seems to be governed by rules or laws that scientists have tried to discover throughout history. And in that they continue. Here are some of the fundamental laws that govern our Universe: Kepler's Laws These are three laws about the movements of the planets formulated by the German astronomer Johannes Kepler in the early 17th century.
The nearby galaxies The closest galaxies to the Milky Way, our neighbors, are those belonging to the so-called Local Group. They are easily seen with an amateur telescope. Some, such as Andromeda and the Magellanic Clouds, can be seen even with the naked eye. Around the Milky Way orbit some dwarf galaxies.
What is the universe? The Universe is everything, without exceptions. Matter, energy, space and time, everything that exists is part of the Universe. It is also called Cosmos. The sciences that study it are several, especially two: astronomy and cosmology. The Universe is very large, but perhaps not infinite.
Measures of the Universe Not only distances, mass, volume, density, temperature can be measured. In the Universe the brightness of the stars, the declination, the wavelength and many other magnitudes are also measured. Let's see what can be measured in the Universe and how it is measured. Measures of the Universe, basic concepts Mass: is the amount of matter of an object.
Novas and supernovas Novas and supernovas are stars that explode releasing part of their material in space. For a variable time, its brightness increases dramatically. It seems that a new star has been born. A nova is a star that greatly increases its brightness suddenly and then pales slowly, but may continue to exist for some time.
The Stars, their types and their evolution Those bright spots in the night sky ... Although most of the space we can observe is empty, it is inevitable that we look at the brightness of each star. It is not that empty space lacks interest, that it has it. Simply, these stars attract our attention.
Classes of Galaxies When powerful telescopes are used, in most galaxies only the mixed light of all stars is detected; however, the nearest show individual stars. The galaxies present a great variety of forms. In 1930 Edwin Hubble classified galaxies into elliptical, spiral and irregular.
Galaxies Galaxies are large structures of the Universe where stars, nebulas, planets, gas clouds, cosmic dust and other materials that are held together by gravitational attraction are grouped together. For most of our history, humans could only see galaxies as diffuse spots in the night sky.
Astronomical catalogs Astronomical catalogs are lists of deep space objects that occupy a fixed position in the sky. They are very useful for astronomers as well as astronomy enthusiasts, since they collect the main galaxies, nebulas and star clusters that can be seen with a medium telescope.