LAMPU LAMPION

When the Sun is low above the horizon, sunlight rays must penetrate the atmosphere for a greater distance, reducing the intensity of the direct light, so that more of the illumination comes from indirect light from the sky (Thomas 1973, 9–13), reducing the lighting ratio. More blue light is scattered, so if the Sun is present, its light appears more reddish. In addition, the Sun's low angle above the horizon produces longer shadows. Golden hour at sunset in Tasmania, Australia The term hour is used figuratively; the effect has no clearly defined duration and varies according to season and latitude. The character of the lighting is determined by the sun's altitude, and the time for the Sun to move from the horizon to a specified altitude depends on a location's latitude and the time of year (Bermingham 2003, 214). In Los Angeles, California, at an hour after sunrise or an hour before sunset, the sun has an altitude of about 10–12°.[2] For a location closer to the Equ

Over 140 million people live permanently at high altitudes (>2,500 m) in North, Central and South America, East Africa, and Asia, and have flourished for millennia in the exceptionally high mountains, without any apparent complications. For normal human populations, a brief stay at these places can risk mountain sickness. For the native highlanders, there are no adverse effects to staying at high altitude. The physiological and genetic adaptations in native highlanders involve modification in the oxygen transport system of the blood, especially molecular changes in the structure and functions of hemoglobin, a protein for carrying oxygen in the body.[48][50] This is to compensate for the low oxygen environment. This adaptation is associated with developmental patterns such as high birth weight, increased lung volumes, increased breathing, and higher resting metabolism. The genome of Tibetans provided the first clue to the molecular evolution of high-altitude adaptation in

The expansion of the universe is the increase of the distance between two distant parts of the universe with time.[1] It is an intrinsic expansion whereby the scale of space itself changes. The universe does not expand "into" anything and does not require space to exist "outside" it. Technically, neither space nor objects in space move. Instead it is the metric governing the size and geometry of spacetime itself that changes in scale. Although light and objects within spacetime cannot travel faster than the speed of light, this limitation does not restrict the metric itself. To an observer it appears that space is expanding and all but the nearest galaxies are receding into the distance. During the inflationary epoch about 10−32 of a second after the Big Bang, the universe suddenly expanded, and its volume increased by a factor of at least 1078 (an expansion of distance by a factor of at least 1026 in each of the three dimensions), equivalent to expanding an o

A fifth giant planet was kicked out of the early solar system, according to computer simulations by a US-based planetary scientist. The sacrifice of this gas giant paved the way for the stable configuration of planets seen today, says David Nesvorný, who believes that the expulsion prevented Jupiter from migrating inwards and scattering the Earth and its fellow inner planets. The Nice model (named after the city in France where it was devised) is currently the best explanation of why the solar system looks the way it does today. It describes how early gravitational interactions between the large outer planets and planetesimals – smaller bodies that are the building blocks of planets – would have scattered the latter throughout the solar system. This accounts for the period known as the “late heavy bombardment”, the scars of which bodies such as the Moon still bear today. It also helps explain the structure of the asteroid and Kuiper belts. However, for the model to work, the plane

In a new study announced on Monday and available in the current volume of Earth and Planetary Science Letters, an international team led by scientists from Brown University in the United States said the planet Mars once had the right water and temperatures to host simple life forms — just not on its surface. Mars's rocky, subterranean layer once, for some hundreds of millions of years, had enough water and reductants to support some of the same kinds of microbial communities seen on Earth. "We showed, based on basic physics and chemistry calculations, that the ancient Martian subsurface likely had enough dissolved hydrogen to power a global subsurface biosphere," reported lead author and current Brown graduate student Jesse Tarnas. The paper does not claim life on Mars did exist but rather that conditions suitable for life are very likely to have lasted for an extended time. This habitable zone, located beneath Mars's then-frozen surface, would have reached