Sunday 18 August 2013

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JUPITER


Jupiter Astronomical symbol of Jupiter
Jupiter by Cassini-Huygens.jpg
A composite Cassini image of Jupiter. The dark spot is the shadow of Europa. The Great Red Spot, a persistent anticyclonic storm, is at lower right. White atmospheric bands, termed zones, represent areas of upwelling; brown bands, called belts, represent areas of downwelling. They display high-altitude ammonia ice clouds and lower clouds of unknown composition, respectively.
Designations
Pronunciation Listeni/ˈpɨtər/[1]
Adjective Jovian
Orbital characteristics[5][a]
Epoch J2000
Aphelion 816,520,800 km (5.458104 AU)
Perihelion 740,573,600 km (4.950429 AU)
Semi-major axis 778,547,200 km (5.204267 AU)
Eccentricity 0.048775
Orbital period
Synodic period 398.88 days[3]
Average orbital speed 13.07 km/s[3]
Mean anomaly 18.818°
Inclination
Longitude of ascending node 100.492°
Argument of perihelion 275.066°
Satellites 67[3]
Physical characteristics
Mean radius 69,911 ± 6 km[6][b]
Equatorial radius
Polar radius
  • 66,854 ± 10 km[6][b]
  • 10.517 Earths
Flattening 0.06487 ± 0.00015
Surface area
  • 6.1419×1010 km2[b][7]
  • 121.9 Earths
Volume
  • 1.4313×1015 km3[3][b]
  • 1321.3 Earths
Mass
  • 1.8986×1027 kg[3]
  • 317.8 Earths
  • 1/1047 Sun[8]
Mean density 1.326 g/cm3[3][b]
Equatorial surface gravity 24.79 m/s2[3][b]
2.528 g
Escape velocity 59.5 km/s[3][b]
Sidereal rotation period 9.925 h[9] (9 h 55 m 30 s)
Equatorial rotation velocity 12.6 km/s
45,300 km/h
Axial tilt 3.13°[3]
North pole right ascension 268.057°
17 h 52 min 14 s[6]
North pole declination 64.496°[6]
Albedo 0.343 (Bond)
0.52 (geom.)[3]
Surface temp. min mean max
1 bar level
165 K[3]
0.1 bar
112 K[3]
Apparent magnitude -1.6 to -2.94[3]
Angular diameter 29.8" – 50.1"[3]
Atmosphere[3]
Surface pressure 20–200 kPa[10] (cloud layer)
Scale height 27 km
Composition
89.8±2.0% hydrogen (H2)
10.2±2.0% helium (He)
~0.3% methane (CH4)
~0.026% ammonia (NH3)
~0.003% hydrogen deuteride (HD)
0.0006% ethane (C2H6)
0.0004% water (H2O)

Ices:
Jupiter is the fifth planet from the Sun and the largest planet in the Solar System.[11] It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in the Solar System combined. Jupiter is classified as a gas giant along with Saturn, Uranus and Neptune. Together, these four planets are sometimes referred to as the Jovian or outer planets. The planet was known by astronomers of ancient times,[12] and was associated with the mythology and religious beliefs of many cultures. The Romans named the planet after the Roman god Jupiter.[13] When viewed from Earth, Jupiter can reach an apparent magnitude of −2.94, bright enough to cast shadows,[14] and making it on average the third-brightest object in the night sky after the Moon and Venus. (Mars can briefly match Jupiter's brightness at certain points in its orbit.)
Jupiter is primarily composed of hydrogen with a quarter of its mass being helium, although helium only comprises about a tenth of the number of molecules. It may also have a rocky core of heavier elements,[15] but like the other gas giants, Jupiter lacks a well-defined solid surface. Because of its rapid rotation, the planet's shape is that of an oblate spheroid (it possesses a slight but noticeable bulge around the equator). The outer atmosphere is visibly segregated into several bands at different latitudes, resulting in turbulence and storms along their interacting boundaries. A prominent result is the Great Red Spot, a giant storm that is known to have existed since at least the 17th century when it was first seen by telescope. Surrounding Jupiter is a faint planetary ring system and a powerful magnetosphere. There are also at least 67 moons, including the four large moons called the Galilean moons that were first discovered by Galileo Galilei in 1610. Ganymede, the largest of these moons, has a diameter greater than that of the planet Mercury.
Jupiter has been explored on several occasions by robotic spacecraft, most notably during the early Pioneer and Voyager flyby missions and later by the Galileo orbiter. The most recent probe to visit Jupiter was the Pluto-bound New Horizons spacecraft in late February 2007. The probe used the gravity from Jupiter to increase its speed. Future targets for exploration in the Jovian system include the possible ice-covered liquid ocean on the moon Europa.

LOIN THE KING OF THE JUNGLE

                                                                                  Lion, The King of the Jungle

Lion Species
These kings of the jungle can weigh between 250 and 550 pounds, depending on sex and age and can grow up to be 14 years old in the wild and over the age of 20 years old in captivity. They become capable at hunting at the age of two and are fully grown after 5 or 6 years. Male lions are distinguishable for their impressive manes, which signifies their masculinity and reflects their health. The darker and thicker the mane, the healthier the lion. It allows the lions to appear stronger and frightening to warn off enemies, particularly humans, and appeals to lionesses that are scientifically proven to mate more with lions with thick and dark manes. Lions with no manes are either genetically inbred or have been castratedWhite Lion
The legendary white lion was once thought to be a figment of one's imagination until less than fifty years ago, when white lion cubs were discovered. This is due a recessive gene and they are not albino as they do have pigmentation in vital parts such as they eye, paw and lip. Their condition is called leucism meaning they only have pigmentation loss in the skin and fur. There are less than fifty white lions in the world.
Man Eaters
Some lions have been known to eat humans however this is thought to only have been done by those who are suffering injuries and disabilities that make it difficult for them to hunt natural prey thus pursuing humans as they are weaker and easier to capture. Several other theories include wanting to defend itself. Another is that their natural habitat is unavailable and not wanting to starve, they attack humans. The thought that lions are predatory towards humans has created ignorance and increased the amount of hunting by encouraging the extermination of these creatures. Humans have taken over territories once belonging to lions and by forcing them to leave their natural home has further demolished their habitat and lifestyle, leaving them to suffer and destruct. Lions are now listed as being a vulnerable species and their population is now irreversibly decreased.
> Prides
Lions have a devised a system of living in groups called prides that's based around related females. The majority of the pride, consisting of approximately 15 individuals and can sometimes even reach 40 individuals, is female with only a handful of male. Male cubs eventually leave and typically become nomads before taking over their own group as the territorial male and father of all cubs. They only leave the pride when challenged by other males and are forced to leave or are killed. Nomads usually travel lone or in pairs, most of the time being related males. If a female nomad attempts to join a pride, it is usually very difficult as the other lionesses reject their intruder who is not related to them.

ALL STAR ARE WHITE


All Stars are White

Bad Astronomy: All stars that you can see at night are white. Good Astronomy: Stars actually emit all the colors of the rainbow. Literally!

I have had a couple of people email me and suggest this as a Bad Astronomy topic. I don't think it's Bad, so much as Not Really Thought About. Most people don't really think about stars having colors, so they tacitly assume all stars are white. But look at the Sun! It looks yellow to me, and it's a star!
This one is easy to disprove by yourself. Go outside on a clear night and look at the stars. The best ones to look at are the brightest. In the Summer, (for the Northern Hemisphere) Vega is a bright star high overhead, and is clearly blue. Antares is another summer star and is also clearly red (or orange). In the Winter, you can see Betelgeuse in the constellation of Orion, which is very red. Aldebaren, a star in Taurus (near Orion) is also very red.
But most of the dimmer stars really do look white. What's going on here?
First off, stars really do have all different colors. Back in the 19th century (and before) it was known that when you heat an object up, it glows, and furthermore the color of the glow depends on the temperature of the object. A man named Wien (pronounced "Veen"; he was German) was even able to apply some math to this and calculate the temperature of an object given its color, although just why this worked was unknown. It wasn't until the 20th century that this was understood, when another scientist named Planck helped develop quantum mechanics.
Mind you, this only works for objects that are glowing, and therefore giving off their own light, and not objects that are simply reflecting light.
Color is just another word for wavelength; light behaves like a wave, and the color of the light depends on the wavelength. Planck worked out a mathematical relation of temperature, color and brightness of a freely glowing object. He found, as Wien did, that an object at a given temperature will emit most of its light at a certain wavelength, and less at all other wavelengths. When you plot up the brightness of an object versus the wavelength (or color), you get a curve now called a "Planck curve", or a "blackbody curve", because it represents a black object heated up. The plot below shows three such curves scaled so that the peak brightness are the same. See how the hottest one (at 7000 degrees Kelvin, a temperature scale much like Centigrade) peaks at a wavelength that is blue, and the cooler one (at 3000 K) at red? The one in between (5500 K) peaks in the green. [Note(added September 29, 2000): the graphic below is a bit confusing. The original colors of the plots matched the stars I discuss in the text, but somehow got messed up when put on the page. I'll fix this when I get a chance. Sorry about the confusion!]
graph of star colors
This is why stars are different colors: they have different temperatures! Vega is a very hot star, and so it glows blue. Betelgeuse is much cooler, and so it looks red. I will point out here that stars are really not blackbodies, and some deviate substantially from being so. They absorb light, taking light from one part of the spectrum and re-radiate it at another. These curves are only approximations. The Sun, for example, should peak at about 5000 Angstroms or so, having a surface temperature of 5500 K. However, due to complicated processes, it actually peaks bluer than that, around 4800 Angstroms (a solar spectrum plot can be found here). Oddly, when you mix all the colors of sunlight, you get white. It may peak in the blue, but the combination of colors (and the way our eye interprets them) makes us perceive this light as white. Many people claim the Sun looks yellow to them. I am not sure why, and have never found an adequate explanation. Is it contrast with the blue sky? I don't know.
So, back to the original question: why do so many stars look white? Are most of them like the Sun?
Nope. Oddly, the vast majority of stars in the sky are cool, red stars, usually too dim to see. The reason most stars appear white to us is because we have two different kind of light sensors in our eyes. Sensors called "rods" detect brightness, while sensors called "cones" detect color. The cones are not very sensitive, so if a light is too dim they are not activated, and we perceive the color as white. So even a red star looks white if it is dim, and only brighter stars look like they have color to us!
If you have a pair of binoculars, look at some stars that are bright but still look white to your naked eye. You'll find that lots of them through the binoculars suddenly have color! The binoculars focus more light into your eye, and for brighter stars there will be enough light to activate the cones in your eye. A telescope will show even more stars with colors. There is a star, named Albireo, that to the naked eye looks like one star, but is actually two in close orbit around each other. One of the stars is a striking red, while the other a brilliant blue. Through even a modest telescope this is one of the most beautiful sights in the sky.

mars

Mars Astronomical symbol of Mars
The planet Mars
Computer-generated view based on a Mars Global Surveyor image mosaic (1999-04). At left, orographic water ice clouds are suspended over the shield volcanoes Olympus Mons, Alba Mons and the Tharsis Montes. The north polar summer (water) ice cap is at top, incised by Chasma Boreale. At lower right, Valles Marineris stretches east-west over 4000 km. Dark areas on the right are lacking in surface dust; the bright area at the lower right limb is the impact basin Argyre.
Designations
Pronunciation Listeni/ˈmɑrz/
Adjective Martian
Orbital characteristics[2]
Epoch J2000
Aphelion 249,209,300 km
1.665 861 AU
Perihelion 206,669,000 km
1.381 497 AU
Semi-major axis 227,939,100 km
1.523 679 AU
Eccentricity 0.093 315
Orbital period 686.971 days
1.8808 Julian years
668.5991 sols
Synodic period 779.96 days
2.135 Julian years
Average orbital speed 24.077 km/s
Mean anomaly 19.3564°
Inclination 1.850° to ecliptic
5.65° to Sun's equator
1.67° to invariable plane[1]
Longitude of ascending node 49.562°
Argument of perihelion 286.537°
Satellites 2
Physical characteristics
Equatorial radius 3,396.2 ± 0.1 km[a][3]
0.533 Earths
Polar radius 3,376.2 ± 0.1 km[a][3]
0.531 Earths
Flattening 0.005 89 ± 0.000 15
Surface area 144,798,500 km2
0.284 Earths
Volume 1.6318×1011 km3[4]
0.151 Earths
Mass 6.4185×1023 kg[4]
0.107 Earths
Mean density 3.9335 ± 0.0004[4] g/cm³
Equatorial surface gravity 3.711 m/s²[4]
0.376 g
Escape velocity 5.027 km/s
Sidereal rotation period 1.025 957 day
24.622 9 h[4]
Equatorial rotation velocity 868.22 km/h (241.17 m/s)
Axial tilt 25.19°
North pole right ascension 21 h 10 min 44 s
317.681 43°
North pole declination 52.886 50°
Albedo 0.170 (geometric)[5]
0.25 (Bond)[6]
Surface temp. min mean max
Kelvin 130 K 210 K[6] 308 K
Celsius −143 °C[8] −63 °C 35 °C[9]
Apparent magnitude +1.6 to −3.0[7]
Angular diameter 3.5–25.1"[6]
Atmosphere[6][13]
Surface pressure 0.636 (0.4–0.87) kPa
Composition
Animation of Mars's rotation from the vantage of an observer who moves south, then north, to hover over both poles, showing the planet's major topographic features.
Mars is the fourth planet from the Sun and the second smallest planet in the Solar System. Named after the Roman god of war, it is often described as the "Red Planet" because the iron oxide prevalent on its surface gives it a reddish appearance.[14] Mars is a terrestrial planet with a thin atmosphere, having surface features reminiscent both of the impact craters of the Moon and the volcanoes, valleys, deserts, and polar ice caps of Earth. The rotational period and seasonal cycles of Mars are likewise similar to those of Earth, as is the tilt that produces the seasons. Mars is the site of Olympus Mons, the second highest known mountain within the Solar System (the tallest on a planet), and of Valles Marineris, one of the largest canyons. The smooth Borealis basin in the northern hemisphere covers 40% of the planet and may be a giant impact feature.[15][16] Mars has two known moons, Phobos and Deimos, which are small and irregularly shaped. These may be captured asteroids,[17][18] similar to 5261 Eureka, a Martian trojan asteroid.
Until the first successful Mars flyby in 1965 by Mariner 4, many speculated about the presence of liquid water on the planet's surface. This was based on observed periodic variations in light and dark patches, particularly in the polar latitudes, which appeared to be seas and continents; long, dark striations were interpreted by some as irrigation channels for liquid water. These straight line features were later explained as optical illusions, though geological evidence gathered by unmanned missions suggest that Mars once had large-scale water coverage on its surface.[19] In 2005, radar data revealed the presence of large quantities of water ice at the poles[20] and at mid-latitudes.[21][22] The Mars rover Spirit sampled chemical compounds containing water molecules in March 2007. The Phoenix lander directly sampled water ice in shallow Martian soil on July 31, 2008.[23]
Mars is currently host to five functioning spacecraft: three in orbit – the Mars Odyssey, Mars Express, and Mars Reconnaissance Orbiter – and two on the surface – Mars Exploration Rover Opportunity and the Mars Science Laboratory Curiosity. Defunct spacecraft on the surface include MER-A Spirit and several other inert landers and rovers such as the Phoenix lander, which completed its mission in 2008. Observations by the Mars Reconnaissance Orbiter have revealed possible flowing water during the warmest months on Mars.[24]
Mars can easily be seen from Earth with the naked eye, as can its reddish coloring. Its apparent magnitude reaches −3.0,[7] which is surpassed only by Jupiter, Venus, the Moon, and the Sun. Optical ground-based telescopes are typically limited to resolving features about 300 km (186 miles) across when Earth and Mars are closest because of Earth's atmosphere.[25]

SPACE


A right-handed three-dimensional Cartesian coordinate system used to indicate positions in space.
Space is the boundless three-dimensional extent in which objects and events have relative position and direction.[1] Physical space is often conceived in three linear dimensions, although modern physicists usually consider it, with time, to be part of a boundless four-dimensional continuum known as spacetime. In mathematics, "spaces" are examined with different numbers of dimensions and with different underlying structures. The concept of space is considered to be of fundamental importance to an understanding of the physical universe. However, disagreement continues between philosophers over whether it is itself an entity, a relationship between entities, or part of a conceptual framework.
Debates concerning the nature, essence and the mode of existence of space date back to antiquity; namely, to treatises like the Timaeus of Plato, or Socrates in his reflections on what the Greeks called khora (i.e. "space"), or in the Physics of Aristotle (Book IV, Delta) in the definition of topos (i.e. place), or even in the later "geometrical conception of place" as "space qua extension" in the Discourse on Place (Qawl fi al-Makan) of the 11th-century Arab polymath Alhazen.[2] Many of these classical philosophical questions were discussed in the Renaissance and then reformulated in the 17th century, particularly during the early development of classical mechanics. In Isaac Newton's view, space was absolute—in the sense that it existed permanently and independently of whether there were any matter in the space.[3] Other natural philosophers, notably Gottfried Leibniz, thought instead that space was in fact a collection of relations between objects, given by their distance and direction from one another. In the 18th century, the philosopher and theologian George Berkeley attempted to refute the "visibility of spatial depth" in his Essay Towards a New Theory of Vision. Later, the metaphysician Immanuel Kant said neither space nor time can be empirically perceived, they are elements of a systematic framework that humans use to structure all experiences. Kant referred to "space" in his Critique of Pure Reason as being: a subjective "pure a priori form of intuition", hence it is an unavoidable contribution of our human faculties.
In the 19th and 20th centuries mathematicians began to examine non-Euclidean geometries, in which space can be said to be curved, rather than flat. According to Albert Einstein's theory of general relativity, space around gravitational fields deviates from Euclidean space.[4] Experimental tests of general relativity have confirmed that non-Euclidean space provides a better model for the shape of space.

THE MILKY WAY


The Milky WayThe Milky Way is one of the many galaxies in the universe and the Sun is one of the 100 billion stars it has in it. The Milky Way is so big in size that it takes light about 100 thousand years to travel from end to end. It tends to look patchy because in some parts of the galaxy the stars are closer to each other, as a result of which those parts tend to shine out brighter than the others, in  other parts dark nebulae block out the light thus giving a patchy effect. Galaxies are of elliptical, irregular and spiral types, the Milky Way is a spiral type of galaxy. It has a curved arm of stars which radiate from a glowing center. The brightest part of the Milky Way is in the constellation called Sagittarius. The Sun and its family are approximately 30,000 light years from the center of the Milky Way. The nearest galaxy to our own is the Magellanic cloud which is about 1,50,000 light years away.