1. Initially some Scientist thought that there is one planet between mercury and sun.
2. Mercury is very near to sun having tempetature of about 1200 – 600 ‘ c.
3. It is the only planet in the universe without atmosphere.
4. Venus ,one of the smallest planet having Albedo 0f 80%.
5. Venus has an extremely dense atmosphere, which consists mainly of carbon dioxide and a small amount of nitrogen. The atmospheric mass is 93 times that of Earth’s atmosphere while the pressure at the planet’s surface is about 92 times that at Earth’s surface—a pressure equivalent to that at a depth of nearly 1 kilometer under Earth’s oceans. The density at the surface is 65 kg/m³ (6.5% that of water). The enormously CO2-rich atmosphere, along with thick clouds of sulfur dioxide, generates the strongest greenhouse effect in the solar system, creating surface temperatures of over 460 °C.
6. Earth , only here , life is possible having a surface temperature of about 65’c.
7. Earth has 21% land surface and 79% water.
8. Mars , the red planet so called because of excess of iron deposit.Much of the surface is deeply covered by a fine iron(III) oxide dust that has the consistency of talcum powder.
9. Mars has approximately half the radius of Earth and only one-tenth the mass, being less dense, but its surface area is only slightly less than the total area of Earth’s dry land.Its surface temperature is only 36’c which will be more hot like 65’c because of iron.
10.Much larger quantities of water are thought to be trapped underneath Mars’s thick cryosphere, only to be released when the crust is cracked through volcanic action.The atmosphere on Mars consists of 95% carbon dioxide, 3% nitrogen, 1.6% argon, and contains traces of oxygen and water.The atmosphere is quite dusty, containing particulates about 1.5 µm in diameter which give the Martian sky a tawny color when seen from the surface.
11.Mars has two tiny natural moons, Phobos and Deimos, which orbit very close to the planet and are thought to be captured asteroids.But Mercury and Venus
doesn’t have natural moons.On August 27, 2003, at 9:51:13 UT, Mars made its closest approach to Earth in nearly 60,000 years: 55,758,006 km (0.372719 AU).
12.Mercury , Venus , Earth and Mars are so called inner planets of this universe.
13.The remaining other are called outer planets.
14.Between Mars ans Jupiter is the Asteriod belt formed because of high gravity between those two planets.
15.The largest asteriod is Cerus which is revolving sun , takes almost 4 1/2 years to complete one rotaion.
16.Jupiter is the largest planet of our universe having almost 64 moons.
17.Upper atmosphere is composed of about 88-92% hydrogen and 8-12% helium by percent volume or fraction of gas molecules .
18.Trace amounts of methane, water vapor, ammonia, and silicon-based compounds. There are also traces of carbon, ethane, hydrogen sulfide, neon, oxygen, phosphine, and sulphur in its atmosphere.
19.Its poular four moons are Callisto,Ganymede,Io,Europa discovered by Gallileo.
20.Callisto is the outermost of teh four gallilean moons having a Thin atmosphere composed of carbon dioxide and probably molecular oxygen, as well as by a rather intense ionosphere.
22.Callisto is not tidaly heated.
23.Ganymede is the largest natural satellite in the universe.
24. It is larger in diameter than the planet Mercury but has only about half its mass.
25.Both Callisto ,Ganymede,Io,Europa – name suggested by astronomer Simon Marius.
26.Ganymede is tidally locked, with one face always pointing toward the planet.
27.Water ice seems to be ubiquitous on the surface, with a mass fraction of 50–90%.
28.Ganymede has carbon dioxide, sulfur dioxide and, possibly, cyanogen, hydrogen sulfate and various organic compounds.
29.Io is the innermost of the four gallilean moons and is the fourth largest moon in the universe.
30. Io’s main source of internal heat comes from tidal dissipation rather than radioactive isotope decay.
31.surface compostition – silicates (such as orthopyroxene), sulfur, and sulfur dioxide.
32. Sulfur dioxide frost is ubiquitous across the surface of Io, forming large regions covered in white or grey materials.
33.Explosive volcanism, often taking the form of umbrella-shaped plumes, paints the surface with sulfurous and silicate materials of Io.
34.The tidal heating produced by Io’s forced orbital eccentricity has led the moon to become one of the most volcanically active worlds in the solar system, with hundreds of volcanic centers and extensive lava flows.
35.The tidal heating produced by Io’s forced orbital eccentricity has led the moon to become one of the most volcanically active worlds in the solar system, with hundreds of volcanic centers and extensive lava flows. During a major eruption, lava flows tens or even hundreds of kilometers long can be produced, consisting mostly of basalt silicate lavas with either mafic or ultramafic (magnesium-rich) compositions.
36.Io has an extremely thin atmosphere consisting mainly of sulfur dioxide (SO2) with a pressure of a billionth of an atmosphere.
37.Europa is tidally locked to Jupiter, with one hemisphere of the satellite constantly facing the planet. Research suggests the tidal locking may not be full, as a non-synchronous rotation has been proposed: Europa spins faster than it orbits, or at least did so in the past.
38.It has an outer layer of water thought to be around 100 km (62 mi) thick; some as frozen-ice upper crust, some as liquid ocean underneath the ice. Recent magnetic field data from the Galileo orbiter showed that Europa has an induced magnetic field through interaction with Jupiter’s, which suggests the presence of a subsurface conductive layer. The layer is likely a salty liquid water ocean.
39.Europa has a tenuous atmosphere composed mostly of molecular oxygen (O2).
40.It has been suggested that life may exist in Europa’s under-ice ocean, perhaps subsisting in an environment similar to Earth’s deep-ocean hydrothermal vents or the Antarctic Lake Vostok. Life in such an ocean could possibly be similar to microbial life on Earth in the deep ocean.
41.Saturn is the second largest planet in the universe.
42. Sixty known moons orbit the planet. Titan, Saturn’s largest and the Solar System’s second largest moon (after Jupiter’s Ganymede), is larger than the planet Mercury and is the only moon in the Solar System to possess a significant atmosphere.
43.The outer atmosphere of Saturn consists of about 93.2% molecular hydrogen and 6.7% helium. Trace amounts of ammonia, acetylene, ethane, phosphine, and methane have also been detected. The upper clouds on Saturn are composed of ammonia crystals, while the lower level clouds appear to be composed of either ammonium hydrosulfide (NH4SH) or water. The atmosphere of Saturn is significantly deficient in helium relative to the abundance of the elements in the Sun.
44.The rings were first observed by Galileo Galilei in 1610 with his telescope, but he was unable to identify them as such.
45. One theory, originally proposed by Édouard Roche in the 19th century, is that the rings were once a moon of Saturn whose orbit decayed until it came close enough to be ripped apart by tidal forces.
46. largest gaps in the rings, such as the Cassini Division and Encke Gap, can be seen from Earth, both Voyager spacecraft discovered that the rings have an intricate structure of thousands of thin gaps and ringlets.
47.Until 1980, the structure of the rings of Saturn was explained exclusively as the action of gravitational forces. The Voyager spacecraft found radial features in the B ring, called spokes, which could not be explained in this manner, as their persistence and rotation around the rings were not consistent with orbital mechanics.
48.Saturn’s major moons – Titan,Mimas,Enceladus,Tethys,Dione,Rhea,Lapetus.
49.Uranus is the seventh planet from the Sun and the third-largest and fourth-most massive planet in the solar system. Uranus was the first planet discovered after 1700.Sir William Herschel announced its discovery on March 13, 1781, expanding the known boundaries of the solar system for the first time in modern history. This was also the first discovery of a planet made using a telescope.
50.Uranus revolves around the Sun once every 84 Earth years. Its average distance from the Sun is roughly 3 billion km (about 20 AU). The intensity of sunlight on Uranus is about 1/400 that of Earth. Its orbital elements were first calculated in 1783 by Pierre-Simon Laplace.
51.Uranus’ mass is roughly 14.5 times that of the Earth, making it the least massive of the giant planets, while its density of 1.27 g/cm³ makes it the second least dense planet, after Saturn. Though having a diameter slightly larger than Neptune (roughly four times Earth’s), it is less massive.
52.Uranus’ internal heat appears markedly lower than that of the other giant planets; in astronomical terms, it has a low thermal flux. Why Uranus’ internal temperature is so low is still not understood.
53.The composition of the Uranian atmosphere is different from the composition of Uranus as a whole, consisting as it does mainly of molecular hydrogen and helium.
54.Uranus has a complicated planetary ring system, which was the second such system to be discovered in the Solar System after Saturn’s. The rings composed of extremely dark particles, which vary in size from micrometers to a fraction of meter. Thirteen distinct rings are presently known, the brightest being the ε ring. All rings of Uranus (except two) are extremely narrow—they are usually a few km wide. The rings are probably quite young; the dynamics considerations indicate that they did not form with Uranus.
55.Uranus has 27 known natural satellites. The names for these satellites are chosen from characters from the works of Shakespeare and Alexander Pope. The five main satellites are Miranda, Ariel, Umbriel, Titania and Oberon.
56.Neptuneis the eighth and farthest planet from the Sun in the Solar System. It is the fourth largest planet by diameter, and the third largest by mass,and the other blue-green planet of our universe.Neptuneis 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 Earth masses and less dense. The planet is named after the Roman god of the sea. Its astronomical symbol is , a stylized version of the god Neptune’s trident.
57.Shortly after its discovery,Neptunewas referred to simply as “the planet exterior to Uranus” or as “Le Verrier’s planet”. The first suggestion for a name came fromGalle, who proposed the name Janus. InEngland, Challis put forward the name Oceanus.
58.Neptune’s internal structure resembles that of Uranus. Its atmosphere forms about 5–10% of its mass and extends perhaps 10–20% of the way towards the core, where it reaches pressures of about 10 GPa. Increasing concentrations of methane, ammonia, and water are found in the lower regions of the atmosphere.
59.At high altitudes, Neptune’s atmosphere is 80% hydrogen and 19% helium.the clouds may consist of ammonia, ammonium sulfide, hydrogen sulfide and water.The stratosphere is also home to trace amounts of carbon monoxide and hydrogen cyanide.The stratosphere ofNeptuneis warmer than that of Uranus due to elevated concentration of hydrocarbons.
60.Neptunehas a planetary ring system, though one much less substantial than that of Saturn. The rings may consist of ice particles coated with silicates or carbon-based material, which most likely gives them a reddish hue. In addition to the narrow Adams Ring, 63,000 km from the centre ofNeptune, the Leverrier Ring is at 53,000 km and the broader, fainter Galle Ring is at 42,000 km. A faint outward extension to the Leverrier Ring has been named Lassell; it is bounded at its outer edge by the Arago Ring at 57,000 km.
61.The outermost ring, Adams, contains five prominent arcs now named Courage, Liberté, Egalité 1, Egalité 2, and Fraternité (Liberty, Equality, and Fraternity). The existence of arcs was difficult to explain because the laws of motion would predict that arcs would spread out into a uniform ring over very short timescales. Astronomers now believe that the arcs are corralled into their current form by the gravitational effects of Galatea, a moon just inward from the ring.
62.Neptune’s more varied weather when compared to Uranus is believed to be due in part to its higher internal heat. AlthoughNeptunelies half again as far from the Sun as Uranus, and receives only 40% its amount of sunlight, the two planets’ surface temperatures are roughly equal.Its temperature = -221.4’c.
63.Neptunehas 13 known moons. The largest by far, comprising more than 99.5 percent of the mass in orbit around Neptune and the only one massive enough to be spheroidal, is Triton, discovered by William Lassell just 17 days after the discovery ofNeptuneitself.
64.Neptune’s second known satellite (by order of discovery), the irregular moon Nereid, has one of the most eccentric orbits of any satellite in the solar system. Neptune’s innermost four moons, Naiad, Thalassa, Despina, and Galatea, orbit close enough to be withinNeptune’s rings.
65.Pluto is the second-largest known dwarf planet in the Solar System (after Eris) and the tenth-largest body observed directly orbiting the Sun. Originally classified as a planet, Pluto is now considered the largest member of a distinct region called the Kuiper belt.
66.The name Pluto was first suggested by Venetia Burney (later Venetia Phair), an eleven-year-old schoolgirl inOxford,England.Venetiawas interested in classical mythology as well as astronomy, and considered the name, one of the alternate names of Hades, the Greek god of the Underworld, appropriate for such a presumably dark and cold world.
67.Pluto’s atmosphere consists of a thin envelope of nitrogen, methane, and carbon monoxide, derived from the ices on its surface. As Pluto moves away from the Sun, its atmosphere gradually freezes and falls to the ground. As it edges closer to the Sun, the temperature of Pluto’s solid surface increases, causing the ices to sublimate into gas. This creates an anti-greenhouse effect; much like sweat cools the body as it evaporates from the surface of the skin, this sublimation has a cooling effect on the surface of Pluto.
68.Pluto has three known natural satellites: Charon, first identified in 1978 by astronomer James Christy; and two smaller moons, Nix and Hydra, both discovered in 2005.The Plutonian moons are unusually close to Pluto, compared to other observed systems. Moons could potentially orbit Pluto up to 53% (or 69%, if retrograde) of the Hill sphere radius, the stable gravitational zone of Pluto’s influence.
69.Beginning in 1992, astronomers began to discover a large population of small icy objects beyondNeptunethat were similar to Pluto not only in orbit but also in size and composition. This belt, known as the Kuiper belt after one of the astronomers who first speculated on the nature of a trans-Neptunian population, is believed to be the source of many short-period comets. Astronomers now believe Pluto to be the largest of the known Kuiper belt objects (KBOs). Like other KBOs, Pluto shares features with comets; for example, the solar wind is gradually blowing Pluto’s surface into space, in the manner of a comet. If Pluto were placed as near to the Sun as Earth, it would develop a tail, as comets do.
70.On September 13, 2006, the IAU included Pluto, Eris, and the Eridian moon Dysnomia in their Minor Planet Catalogue, giving them the official minor planet designations “(134340) Pluto”, “(136199) Eris”, and “(136199) Eris I Dysnomia”. If Pluto had been given a minor planet name upon its discovery, the number would have been a little over a thousand rather than over 100,000. The first minor planet to be found after Pluto was 1164 Kobolda, a month later.In January 2007, the American Dialect Society chose “plutoed” as its 2006 Word of the Year, defining “to pluto” as “to demote or devalue someone or something”, “as happened to the former planet Pluto when the General Assembly of the International Astronomical Union decided Pluto no longer met its definition of a planet.”
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