کهکشان راه شیری: Milky Way Galaxy

Milky Way Galaxy, commonly referred to as just the Milky Way, or sometimes simply as the Galaxy, is the galaxy in which the Solar System is located. The Milky Way is a barred spiral galaxy that is part of the Local Group of galaxies. It is one of hundreds of billions of galaxies in the observable universe. Its name is a translation of the Latin Via Lactea, in turn translated from the Greek Γαλαξίας (Galaxias), referring to the pale band of light formed by stars in the galactic plane as seen from Earth (see etymology of galaxy).

Some sources hold that, strictly speaking, the term Milky Way should refer exclusively to the band of light that the galaxy forms in the night sky, while the galaxy should receive the full name Milky Way Galaxy, or alternatively the Galaxy.^[13][14][15] However, it is unclear how widespread this convention is, and the term Milky Way is routinely used in either context.

Dolphins

Dolphins are marine mammals that are closely related to whales and porpoises. There are almost forty species of dolphin in seventeen genera. They vary in size from 1.2 m (4 ft) and 40 kg (90 lb) (Maui's dolphin), up to 9.5 m (30 ft) and 10 tonnes (9.8 LT; 11 ST) (the orca or killer whale). They are found worldwide, mostly in the shallower seas of the continental shelves, and are carnivores, mostly eating fish and squid. The family Delphinidae is the largest in the Cetacean order, and evolved relatively recently, about ten million years ago, during the Miocene. Dolphins are among the most intelligent animals, and their often friendly appearance and seemingly playful attitude have made them popular in human culture. 

 

Etymology

The name is originally from Greek δελφίς (delphís), "dolphin",^[1] which was related to the Greek δελφύς (delphus), "womb".^[2] The animal's name can therefore be interpreted as meaning "a 'fish' with a womb".^[3] The name was transmitted via the Latin delphinus^[4] (the romanization of the later Greek δελφῖνος - delphinos^[5]), which in Middle Latin became dolfinus and in Old French daulphin, which reintroduced the ph into the word. The term mereswine has also historically been used.^[6]

The word is used in a few different ways. It can mean:

• any member of the family Delphinidae (oceanic dolphins),
• any member of the families Delphinidae and Platanistoidea (oceanic and river dolphins),
• any member of the suborder Odontoceti (toothed whales; these include the above families and some others),
• and is used casually as a synonym for bottlenose dolphin, the most common and familiar species of dolphin.

This article uses the second definition and does not describe porpoises (suborder Odontoceti, family Phocoenidae). Orcas and some closely related species belong to the Delphinidae family and therefore qualify as dolphins, even though they are called whales in common language. A group of dolphins is called a "school" or a "pod". Male dolphins are called "bulls", females "cows" and young dolphins are called "calves".

fire waterfall ابشار اتش

                              

منبع عکس :سایت گوگل

This park was gazetted as a national park in 1890. It is world famous for its rugged terrain, waterfall and century-old pine trees. It covers 1200 sq km and the "fire" waterfall of El Capitan is one of the most spectacular of all scenery.  

The spectacular view of the waterfall is created by the reflection of sunlight hitting the falling water at a specific angle. This rare sight can only be seen at a 2-week period towards the end of February. To photograph this rare event, photographers would often have to wait and endure years of patience in order to capture them. The reason is because its appearance depends on a few natural phenomena occurring at the same time...and some good luck.

What is Hardware?

Your PC (Personal Computer) is a system, consisting of many components. Some of those components, like Windows XP, and all your other programs, are software. The stuff you can actually see and touch, and would likely break if you threw it out a fifth-story window, is hardware.

Not everybody has exactly the same hardware. But those of you who have a desktop system, like the example shown in Figure 1, probably have most of the components shown in that same figure. Those of you with notebook computers probably have most of the same components. Only in your case the components are all integrated into a single book-sized portable unit.

Figure 1

9 Mistakes You Should Avoid in Your Nutrition Habits

۹Mistakes You Should Avoid in Your Nutrition Habits

1.  Not having breakfast

It is a big mistake to ignore and not have breakfast. A healthy breakfast not only can provide sufficient energy to several body organs but it also contributes to choosing healthier materials for other daily meals.

2. Eating before going to bed

Try to avoid eating before going to bed if you want to have nice dreams. Scientists revealed that eating spicy and fat full foods within one to three hours before sleep will lead to exhaustion and bored ness on the next day.

3.  Anorexia

Anorexia or overeating usually accounts for fat full meals resulting in overweight. Try to extend your daily meals to five or more instead of having only three.

4.  Staying hungry

When you stay hungry for a long time, your body becomes exhausted for not having enough supplies. This will lead you to eat overwhelmingly and your body changes the calorie to fat automatically.

Rainbow

A rainbow is an optical and meteorological phenomenon that causes a spectrum of light to appear in the sky when the Sun shines on to droplets of moisture in the Earth's atmosphere. It takes the form of a multicoloured arc, with red on the outer part of the arc and violet on the inner section. A rainbow spans a continuous spectrum of colours; the distinct bands are an artifact of human colour vision. The most commonly cited and remembered sequence, in English, is Newton's sevenfold red, orange, yellow, green, blue, indigo and violet (popularly memorized by mnemonics like Roy G. Biv). Rainbows can be caused by other forms of water than rain, including mist, spray, and dew. 

Rainbows can be observed whenever there are water drops in the air and sunlight shining from behind at a low altitude angle. The most spectacular rainbow displays happen when half the sky is still dark with raining clouds and the observer is at a spot with clear sky in the direction of the sun. The result is a luminous rainbow that contrasts with the darkened background.

The rainbow effect is also commonly seen near waterfalls or fountains. In addition, the effect can be artificially created by dispersing water droplets into the air during a sunny day. Rarely, a moonbow, lunar rainbow or nighttime rainbow, can be seen on strongly moonlit nights. As human visual perception for colour is poor in low light, moonbows are often perceived to be white.^[1] It is difficult to photograph the complete semicircle of a rainbow in one frame, as this would require an angle of view of 84°. For a 35 mm camera, a lens with a focal length of 19 mm or less wide-angle lens would be required. Now that powerful software for stitching several images into a panorama is available, images of the entire arc and even secondary arcs can be created fairly easily from a series of overlapping frames. From an aeroplane, one has the opportunity to see the whole circle of the rainbow, with the plane's shadow in the centre. This phenomenon can be confused with the glory, but a glory is usually much smaller, covering only 5–20°.

At good visibility conditions (for example, a dark cloud behind the rainbow), the second arc can be seen, with inverse order of colours. At the background of the blue sky, the second arc is barely visible. 

The seven colours of the rainbow

A rainbow spans a continuous spectrum of colours—there are no "bands." The apparent discreteness is an artefact of the photopigments in the human eye and of the neural processing of our photoreceptor outputs in the brain. Because the peak response of human colour receptors varies from person to person, different individuals will see slightly different colours, and persons with colour blindness will see a smaller set of colours. However the seven colours listed below are thought to be representative of how humans everywhere,^[35] with normal colour vision, see the rainbow.

Newton originally (1672) named only five primary colours: red, yellow, green, blue and violet. Later he included orange and indigo, giving seven colours by analogy to the number of notes in a musical scale.^[36]

Red:     . Orange:     . Yellow:     . Green:     . Blue:     . Indigo:     . Violet:    .

Dragonfly:سنجاقک

A dragonfly is an insect belonging to the order Odonata, the suborder Epiprocta or, in the strict sense, the infraorder Anisoptera. It is characterized by large multifaceted eyes, two pairs of strong transparent wings, and an elongated body. Dragonflies are similar to damselflies, but the adults can be differentiated by the fact that the wings of most dragonflies are held away from, and perpendicular to, the body when at rest. Dragonflies possess six legs (like any other insect), but most of them cannot walk well. Dragonflies are some of the fastest insects in world.

Dragonflies are valuable predators that eat mosquitoes, and other small insects like flies, bees, ants, and very rarely butterflies. They are usually found around lakes, ponds, streams and wetlands because their larvae, known as "nymphs", are aquatic.

Mariana Trench:گودال ماریانا عمیق ترین گودال جهان

Location of the Mariana Trench

The Mariana Trench is the deepest part of the world's oceans, and the lowest elevation of the surface of the Earth's crust. It is located in the western Pacific Ocean, to the east of the Mariana Islands. The trench is about 2,550 kilometres (1,580 mi) long but has a mean width of only 69 kilometres (43 mi). It reaches a maximum-known depth of about 11.03 kilometres (6.85 mi) at the Vityaz-1 Deep and about 10.91 kilometres (6.78 mi) at the Challenger Deep, a small slot-shaped valley in its floor, at its southern end.^[1] If Mount Everest, the highest mountain on Earth at 8,848 metres (29,029 ft), were set in the deepest part of the Mariana Trench, there would be 2,076 metres (6,811 ft) of water left above it.^[2]

Part of the Izu-Bonin-Mariana Arc system trenches forms the boundary between two tectonic plates, where the western edge of the Pacific Plate is subducted beneath the small Mariana Plate. Because the Pacific plate is the largest of all the tectonic plates on Earth, crustal material at its western edge has had a long time since formation (up to 170 million years) to compact and become very dense; hence its great height-difference relative to the higher-riding Mariana Plate, at the point where the Pacific Plate crust is subducted. This deep area is the Mariana trench proper. The movement of these plates is also responsible for the formation of the Mariana Islands.

At the bottom of the trench, where the plates meet, the water column above exerts a pressure of 1,086 bars (15,750 psi), over one thousand times the standard atmospheric pressure at sea level.

Because the Earth is not a perfect sphere, the trench is not the part of the seafloor closest to the center of the Earth - parts of the Arctic Ocean seabed are at least 13,000 metres closer to the center than the Challenger Deep seafloor

http://en.wikipedia.org/wiki/Mariana_Trench

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