What’s In The Universe?
The Universe is the ultimate mystery of this whole story. And of course that I don’t have answer to this question – if it’s not “42” :) The beginning are not clear and is hard to guess where it might have come from. The term universe may be used in slightly different contextual senses, denoting such concepts as the cosmos, the world, or nature. Cosmos and the Universe are just small parts of the Macrocosmos and gravitational energy is equal and opposite to the matter energy in a closed space. What is the Big Bang? The Big Bang is cosmological theory of the early development of the universe.
The universe existed around 13.7 billion years ago. About 300 thousand years after the Big Bang, the Universe had cooled enough for electrons to be captured by protons and alpha particles to form atoms. Over a long period of time gravitationally attracted nearby matter formed gas clouds, stars, galaxies, and the other astronomical structures. Careful studies of the distribution of these galaxies and their spectral lines have led to much of modern cosmology. The details of this process depend on the amount and type of matter in the Universe. A galaxy is an island of billions of stars. There are billions of other galaxies probably very similar to ours. Galaxies are either spiral (about 70% of galaxies – similar to the Milky Way) or elliptical (about 30%).
A few are other shapes. Stars are formed continuously in spirals and in the spiral galaxy we live. A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas dust, and an important but poorly understood component tentatively dubbed dark matter. Independent lines of evidence from Type Ia supernovae and the CMB imply that the Universe today is dominated by a mysterious form of energy known as dark energy, which apparently permeates all of space.
The nearest star to us is the Sun. The next nearest star is Proxima Centauri in the constellation Centaurus. Proxima Centauri is very close to the nearest visible star, Alpha Centauri. Proxima and Alpha are thought to be associated by gravity because they have a similar motion in space. There’s a new telescope the VLT Survey Telescope (VST), a wide-field survey telescope with a field of view twice as broad as the full Moon, enabling new, spectacular views of the cosmos. It is the largest telescope in the world designed to exclusively survey the sky in visible light. Over the next few years the VST and its camera OmegaCAM will make several very detailed surveys of the southern sky. The Solar System consists of the Sun and the astronomical objects. Of the many objects that orbit the Sun, most of the mass is contained within eight relatively solitary planets whose orbits are almost circular and lie within a nearly flat disc called the ecliptic plane.
Further improvements in astronomy led to the realization that the Solar System is composed of billions of stars, the Milky Way, and that other galaxies exist outside it, as far as astronomical instruments can reach. A star (such as the Sun) is a ball of gas which has, a nuclear fusion reactor. Stars are the places where large atoms are built. Past generations of stars formed the gas and dust from which the planets and life were made. Two large planets, Jupiter and Saturn, were the first to form. They are mostly gas. These massive planets probably had a great influence on how the rest of the solar system evolved. They were in almost perfect circular orbits. Most of the giant planets are in elliptical orbits. Later four small rocky planets formed near the Sun: Mercury, Venus, Earth and Mars. Life later evolved on Earth. These planets too had almost circular orbits. If they had oval orbits, life could not have evolved. Another planet started to form but broke up into pieces because of the gravity of Jupiter. It formed a ring of small rocks where the planet should have been. We call them the asteroids. Beyond Saturn there are two gassy planets, Uranus and Neptune and a little icy planet Pluto.
Far out beyond Pluto there are many icy objects like the snowballs which formed the planets. They are the comets, and sometimes some of them wanders in near the Sun. Plants first appeared on Earth in the form of blue-green bacteria about 3.5 billion years ago. The algae appeared around 1.5 billion, and colonies of them around 1 billion years ago. Land plants appeared around 500 million years ago and had evolved into tree ferns about 350 million. Seeds appeared about 300 million years ago and fruits about 200 million. Grasses appeared about 50 million years ago. Bacteria have only one cell each and the first cells appeared on Earth about 3.5 billion years ago.
The third major type of animal was not closely related to the molluscs or arthropods. It is not clear which of the invertebrates was their ancestor, perhaps early flatworms. Although not so successful in terms of numbers they were far more successful in other ways. They first appeared around 500 million years ago, and are called the vertebrates, meaning “with backbone”. Bone was a key factor in the success of the vertebrates. All animals which do not have backbones (everything except the vertebrates) are called invertebrates. Modern people (Homo Sapiens) seem to have evolved in Africa about 100 thousand years ago and lived there while the Neanderthals were spreading around the world. An interglacial (warm period) began 35 thousand years ago. Then modern people came out of Africa and spread. Within a few thousand years they replaced the Neanderthals in Europe and Asia. Then about 25 thousand years ago the weather turned cold again and a glacial began, known as the Ice Age.