New Light of Earth

Apart from our star, the Sun, and some small stars (comets, asteroids, etc.), the solar system includes 8 planets that can be divided into three categories. There are 4 terrestrial planets, that is to say having a rocky and therefore solid surface: Mercury, Venus, Earth and Mars, to which is added Pluto which is a dwarf planet. Then, there are 4 gaseous giant planets that do not have a solid surface: Jupiter, Saturn, Uranus and Neptune that we will describe next page. The terrestrial planets are not larger than the Earth while all the gaseous planets are between 4 and 11 times larger than the Earth. The Giant Planets There are 4 giant Jovian planets in the solar system: Jupiter, Saturn, Uranus and Neptune. Place Pluto, Eris and 2007 OR10 apart as they are very small and look like the moon; their surface is frozen and do not consist of gas. We will speak again. These 4 giant planets do not have a solid surface. If you dive with a spaceship in the atmosphere of Jupiter or Sat...

Our Galaxy forms a disc a little thicker in the center that is observed in profile, which is why the Milky Way seems very long and quite thin. The stars are concentrated in the central part located in the constellation Sagittarius. It is the widest and brightest region. Paradoxically it is also the most opaque region of the Milky Way because it contains a lot of dust that hides the light of the stars in the background; these are all the dark stripes that you see in the middle of the picture below. At the ends, near the constellations of the Coachman (Auriga) and Gemini (Gemini), it dissipates and can hardly be seen with the naked eye among the nearby stars. Thanks to radio astronomy and infrared telescopes that can cross dark clouds of dust to observe the other side of the Milky Way, almost all of its shape has been determined. Thus it was discovered that our galaxy had several very tight spiral arms that wrapped around the nucleus. She is escorted by two satellite galaxies, th...

Light is electromagnetic radiation within a certain portion of the electromagnetic spectrum. The word usually refers to visible light, which is the visible spectrum that is visible to the human eye and is responsible for the sense of sight. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), or 4.00 × 10−7 to 7.00 × 10−7 m, between the infrared (with longer wavelengths) and the ultraviolet (with shorter wavelengths). This wavelength means a frequency range of roughly 430–750 terahertz (THz). Wikipedia The light is something very special, very far in reality to resemble what people imagine. Light is represented in the form of a wave like the sound of the radio but which moves much faster, from the order of 300000 km/s in the vacuum, or 1 billion km/h, while the sound travels in the air at only 300 m/s (1080 km/h or Mach 1 as airplane pilots). It is this phenomenon that explains for example why you immediately see the lightning during a...

The luminous ball that enlightens us during the day is actually a star like all the ones you can see at night in the sky, with the only difference that it is much closer than the others, to be precise 272000 times closer than Proxima of the Centaur which is the closest star of the solar system to 4.3 light-years! Like all stars, the Sun is an immense ball of very hot gas whose temperature is about 6000 ° C on the surface but reaches millions of degrees in the heart of the star. Its material consists essentially of incandescent hydrogen mixed with a little helium. The Sun is gaseous on the surface but it becomes rapidly fluid and probably solid at the depth due to the very high pressures that prevail there. But all this is done gradually. The Sun turns on itself like a sticky balloon. At the equator, for example, the surface of the Sun turns on itself in 25.4 days whereas at the pole its rotation lasts 32 days. The Sun being a ball of luminous gas, it has no solid surface lik...

Astronomy is a beautiful pastime that allows you to escape into space during your spare time and to observe sparkling multicolored stars, ringed planets like Saturn, the crescent of Venus, the sunspots, the innumerable Craters of the Moon, shooting stars or even galaxies. All you need is an astronomical telescope or a telescope or some beautiful books or educational software richly illustrated. In fact you would need both: a telescope to observe the sky and some books or software to learn more about the stars you observe. We will talk about it again, but above all there are some rules to respect if you wish to observe the sky in good conditions and make the most of your evening. To observe the sky you must first prepare yourself, know what stars or planets are visible during the night, where to look for them and with which instrument you can observe them. Tga general, information, artifact, old, gallery, illustration

Sometimes white, sometimes red, crescent-shaped, oval or perfectly round, the Moon has been the faithful companion of the Earth for billions of years. Born at the same time as the Earth the Lady of Night aged prematurely but its gaze has kept all its intensity and still dreams many observers who courtez it when it deigns to appear above the horizon. The Moon is not a planet because it does not turn around the Sun; The moon revolves around the Earth. It is therefore the natural satellite of the Earth. But there are also so-called artificial satellites that revolve around the Earth and are used for telecommunications or for studying our planet. The Moon orbits very far from Earth, about 384,000 km away while most artificial satellites revolve around the Earth at about 500 km altitude, some 36,000 km as geostationary satellites. The Moon is so far that it takes 4 days to reach it in rocket. We will talk about it in the page devoted to the exploration of the Moon. The Moon al...

During the time of Newton and the discovery of experimentation, the universe was eternal and ageless. Time was an independent variable whose course could not be altered. Scientists could understand space, measure distances, weigh masses, and calculate elapsed time. They assessed absolute events. By "inventing" gravitation, Newton created a universal law that applied everywhere and at all times. It is a dynamic and reversible law. There is no difference between a film of a planet moving forward and the same movement filmed in reverse. The two phenomena are equivalent. Aware of some anomalies in classical theories, Einstein integrated this law into his theory of relativity in 1905. Einstein's equations describe a universe where space is linked to time, which Minkowski called the "space-time continuum". Einstein also postulated the existence of a speed limit in a vacuum, i.e. the speed of light. At the same time, the French writer Gaston de Pawlowski was wri...