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Saturday, 17 January 2015

The Solar System And Planets


The solar system is, so to say, our "neighborhood" in space. The Earth, which is our home, orbiting the Sun making a revolution, ie a round, per year. Together with eight other major planets orbit the Earth, two closest to the Sun, the other more distant. Besides these there are dozens of moons that orbit the planets, and thousands of minor bodies, such as asteroids and comets.

The Sun is the body by far the largest of the system and that's what, with its heat, warms everyone else, that the orbit. This set of bodies is the Solar System and has originated from the same cloud about 5 billion years ago. We will see together some slides of the main bodies of the system, imagining a journey from the Sun to the suburbs. Most of the images that we will have been taken from scientific satellites with on-board special cameras that can work in the space, at temperatures and prohibitive conditions. 

Sun:

We perceive the sunlight and see sometimes it’s hard to sunset or behind a blanket of clouds. The light that warms us takes less than 8 minutes to get to us which means - at about 300,000 kilometers per second, which is the speed of light - that the Sun is approximately 149.5 million kilometers away from us, or 1 astronomical unit (UA). The diameter of the Sun is about 1.4 million kilometers.

The energy produced by the core a little at a time, By committing about a hundred thousand years since it was first produced (in a vacuum would take 2 seconds), comes out on the surface of the sun, that the photosphere, where there are about 6000 degrees, and then takes eight minutes to get to the Earth through the short layer of the chromosphere and then the crown, an immense cloud of plasma that surrounds the entire Sun and that fades slowly in space.

As you can see from the pictures, the Sun is not a quiet place to spend the weekend. From Earth, with our telescopes properly filtered can see various phenomena, such as sunspots. These in particular are areas where the magnetic field becomes so intense that blocks the warm currents which rise from below to warm the surface, and then the areas appear darker because slightly colder (we talk of less than one thousand degrees less of about six thousand degrees). The warm currents that peek on the surface appear as grains: why the Sun through a telescope looks wrinkled like the skin of an orange.

Mercury 

If the Sun were great an inch, and the Earth far it was 1 meter (then 1UA = 1m), the first planet that would meet, at 39 cm, would be Mercury. As you can see from the pictures, this planet looks a little like our Moon. The diameter of Mercury is 4878 km, and less than half of the Earth. The filming of the probe Mariner 10, which was the first to approach the planet, in 1973, have now been replaced by those of the probe Messenger. There are craters, like the Moon, and flat surfaces.

The day, which is the period of the day when there is the Sun, Earth lasts 176 days with temperatures around 400 ° C
Mercury has no seasons, and then the Sun, during the year, it is always at the same height. There are craters that never see the sun, and are thus always extremely cold temperatures. Some surveys conducted with radio telescopes would have shown the characteristics of ice reflections.

Venus

So get away from Mercury and 72 cm from the Sun (0.72 AU) meet Venus, the second planet of the Solar System and the one whose orbit is closest to Earth. It is often seen at dusk or dawn, and appears very bright.

It has the same size as Earth, and probably a time Earth and Venus were similar. The development, however, was completely different. The temperature of Venus is 460 ° C, so that the rocks appear luminescent. The climate is dominated by a very effective greenhouse, because the large amount of CO2 traps heat from the Sun (Mercury, where there is no atmosphere, the heat escapes at night).
 There is no free water, and there is a ground pressure of about 90 atmospheres.

Earth

As you know well, however, a few feet from our Sun (1 AU) is the planet with a very large satellite: the Moon. The Earth seen from space is very nice, but at night you see so many unnecessary lights that waste energy and resources and pollute so much: it is the phenomenon of 'light pollution.

Mars

At 152 cm from the Sun (1,52UA) is the red planet, Mars, which is visible to the naked eye. It has an equatorial diameter of 6786 km (the Earth has 12,700) and has polar caps where there is strong evidence of the presence of water ice.

Many pictures taken from various probes showed some real rivers dry, a sign that the planet was once liquid water, essential for life. No atmosphere, although it is much more tenuous than the Earth: the pressure is only 6 thousandths of atmosphere (about 6 milli bars). There are many craters, valleys and plains, and there is also the largest volcano in the solar system: Olympus Mons.

Jupiter

At 5.2 meters from the Sun (5.2 AU) meet the first gaseous planet, ie on the surface you cannot walk. This is Jupiter, who observed with a small telescope shows its stripes and its major satellites, discovered by the great Italian astronomer Galileo Galilei.

Jupiter than Earth, is huge: it has an equatorial diameter of 143,000 kilometers, compared to 12,700 of the Earth. Its atmosphere has bands of clouds and stains, and is composed of methane, ammonia, H, He, C, N.

Emits three times more heat than it receives from the Sun, thus helping to warm its satellites, which are very interesting and we will see quickly. Jupiter, like all gas giants, presents a ring, not visible to the naked eye even with larger telescopes, but resumed by interplanetary probes that have studied.

Saturn

At 9.5 meters from the Sun is Saturn, the second planet by diameter. With a small telescope you can see its rings and its moon main, Titan. And 'the farthest planets easily visible to the naked eye, and 'the second, also by distance from the Sun, the four gas giants, and has an atmosphere composed principal men ballet hydrogen (H) and helium (He). Takes 29.5 years to complete one revolution around the sun. The atmosphere resembles that of Jupiter.

Saturn is most famous for its spectacular rings which are inclined at 28 ° to the orbit and are structured in different groups. Are very thin: with a diameter of 250,000 kilometers have thickness of only 1 km.

Uranus

And 'the seventh planet, another gas giant, visible with a little' difficulty to the naked eye, but easily observed with a small telescope. It was discovered in 1781 by William Herschel. And 'far, more than twice the distance of Saturn: 19.2 UA. E 'was only visited by Voyager 2 in January 1986.

 The planet "roll" along its orbit, as the axis of rotation is perpendicular to the revolution. This is due to a collision with a great body at the dawn of the Solar System. The orbital period is 84 years. Have very thin rings, which were discovered from the ground.

Neptune

It was discovered in 1846 and visited by Voyager 2 in 1989. The engineers struggled with the lack of available light for the filming of its surface, but eventually got the beautiful images. It 'a gas giant and has 4 rings and 8 satellites. It is located at 30.1 AU.

Pluto (134340) (dwarf planet)

Was only discovered in 1930 by Charles Tombaught and for 76 years has been considered the ninth planet in the solar system. On 25 August 2006, during the IAU Congress 2006 in Prague, the IAU-International Astronomical Union redefined the parameters for the identification of the planets and was introduced the new class of objects called "dwarf planets" (dwarf planets), in which were included the former asteroid Ceres, Pluto, Eris (2003 UB313) and perhaps others in the future.

Later he was assigned an identification also asteroid; its catalog number becomes therefore 134340.

Pluto is located at an average distance of 39.5 AU from the Sun and has a satellite half the size of the planet, Charon, 1,100 km in diameter. Not much is known of this body, which was until 2006 the smallest and most distant of the planets has a diameter of 2200 km and only the Hubble Space Telescope has allowed mapping course. And 'the only object over 2000 kilometers in diameter to be not yet been visited by a space mission.