Comets: The Oort Cloud The Oort cloud is a large concentration of comets subjected to the forces of the Sun and other stars. In the article The Oort Cloud, Paul R. Weissman, an expert in cometary dynamics, talks about these comets that orbit beyond Pluto. A fragment of this article is reproduced here in which the author begins by raising the question of the number of comets that form this immense cloud.
Articles about the Universe In 1929 astronomer Edwin Hubble discovered that the speeds of distance or recession of galaxies increased with the growth of their distances. This discovery gave rise to the cosmological theory of the Big Bang, which starts from the hypothesis that all the matter in the Universe was concentrated in an undefined sphere and that, after its explosion, began to expand, creating the space-time binomial.
Planets in other solar systems Knowing whether or not we are alone in the universe has been one of the goals of many philosophers and scientists throughout history. Until recently, the only known planets were part of the Solar System. The discovery of extrasolar planets is a fairly recent event.
Planets of the Solar System Essentially, a planet differs from a star in its much smaller amount of mass. Because of this deficit, the planets do not develop thermonuclear fusion processes and cannot emit their own light; limited to reflect that of the star around which they rotate.
The energy of the stars The stars emit energy in different ways: 1. In the form of mass-free electromagnetic radiation photons, from the more energetic gamma rays to the less energetic radio waves (even the cold matter radiates photons; the colder it is matter, the weaker the photons).
Cosmic dust According to current astronomical theories, galaxies had their origin in large conglomerates of gas and cosmic dust that turned slowly, fragmenting into turbulent vortices and condensing into stars. In some regions where star formation was very active, almost all dust and gas went to one star or another.
Our galaxy, the Milky Way The Milky Way we can see in the night sky is actually just one of the spiral arms of our own galaxy, which takes, by extension, the same name. Our galaxy is a grouping of some 300,000 million spiral-shaped or spinning stars, whose dimensions are estimated at around 100.
Nebulae A nebula is a cloud of gas or dust in space. Nebulae can be dark or, if illuminated by nearby stars or stars immersed in them, they can be bright. They are generally places where the formation of stars and planetary discs occurs, so that very young stars are usually found within it.
Astronomy and astrophysics readings Astronomy is the science that studies the events of the cosmos, the structures that form it and the laws that govern it. Astrophysics is physics applied to astronomy. In ancient times, astronomy and astrology were the same, two inseparable "sciences."
Sedna, the tenth planet in the Solar System? Researchers sponsored by NASA have discovered the most distant object in orbit of the Sun. It is a mysterious planet-like body in the confines of the Solar System, which is three times farther from Earth than Pluto. The Sun appears so small from that distance that it could be completely covered with the head of a pin.
Comets in the sky The ancients, observing that the comets appeared and disappeared in an unpredictable way, surrounded by a pale hair and followed by an extremely changeable tail, had no doubts: they were something that came to disrupt the celestial order. The very fact that the comets did not follow the movement of the planets, only strengthened this belief that led the comets to be responsible for generally serious historical events.
Articles about the Earth and the Moon The Earth is considered as a physical system, so that all its phenomena are investigated and decomposed into physical and chemical aspects to reach a better understanding of its structure, its exact composition and its evolution throughout of geological history.
Origin of the Solar System Since Newton's time it has been possible to speculate about the origin of the Earth and the Solar System as a problem different from that of the creation of the Universe as a whole. The idea of the Solar System was that of a structure with certain unified characteristics: 1.
Can we travel to the planet Mars? NASA has a mystery to solve: Can we send people to Mars, or not? It is a matter of radiation. We know the amount of radiation out there, waiting for us between Earth and Mars, but we are not sure how the human body will react to it.
The formation of the air The opinion of the astronomers is that the planets were born from whirlpools of gas and dust, constituted in general by the diverse elements present, in proportions corresponding to their cosmic abundance. About 90 percent of the atoms were hydrogen and another 9 percent was helium. The rest included all other elements, mainly neon, oxygen, carbon, nitrogen, carbon, sulfur, silicon, magnesium, iron and aluminum.
The orbits of the planets Why do all the planets occupy, more or less, the same orbital plane? The best astronomical conjecture indicates that they move in the same orbital plane because they were born from the same and unique disk of matter that was quite flat. Theories suggest that the Solar System was originally a huge mass of rotating gas and dust, perhaps spherical at first.
The dance of the continents The interior of our planet is at enormous temperatures that generate the innermost layers in a plastic or semi-molten state. Precisely for this reason, convection systems appear very similar to those produced in gas stoves and radiators.
What is the greenhouse effect? When we say that an object is "transparent" because we can see through it, we do not necessarily mean that all types of light can pass through it. Through a red crystal, for example, it can be seen, being, therefore, transparent. But instead, the blue light does not pass through it.
Origin of the Solar System (III) Since 1900 the nebular hypothesis lost so much strength to explain the formation of the Solar System, that the idea of any evolutionary process seemed discredited forever. The stage was set for the resurrection of a catastrophic theory. In 1905, two wise Americans, Thomas Chrowder Chamberlin and Forest Ray Moulton, proposed a new one, which explained the origin of the planets as the result of a quasi-collision between our Sun and another star.
Earth-touching asteroids and Apollo objects If the asteroids penetrate beyond the orbit of Jupiter, would there not be others that penetrate beyond the orbit of Mars, closer to the Sun? The first of such cases was discovered on August 13, 1898 by a German astronomer, Gustav Witt.
Novas and supernovas Before the era of astronomy, a star that suddenly appeared where nothing had been seen before, was called nova, or "new star." This is an inappropriate name, since these stars existed long before they could be seen with the naked eye. Astronomers believe that there may be a dozen novae in the Milky Way, the Earth's galaxy, every year, but two or three of them are too far away to be seen or obscured by interstellar matter.