V. Give the brief characteristic of the Inner Solar System.
VI. Have you got anything to add?
Mid Solar System
I. Learn active vocabulary:
Centaur - центавр
denizen – житель, обитатель
bulk – масса, количество
superior planet – старшая планета
cloud band – облачная гряда
retrograde orbit – обратная орбита
volatile ice – летучий лед
coma – оболочка кометы, голова кометы
debris – обломки пород, пустая порода
to overlap – частично совпадать
erratic orbit – непостоянная орбита
II. Read and translate the text:
The middle region of the Solar System is home to the gas giants and their planet-sized satellites. Many short period comets also lie in this region. It is occasionally referred to as the “outer Solar System”. The solid objects in this region are composed of a higher proportion of “ices” (water, ammonia, methane) than the rocky denizens of the inner Solar System.
Outer planets
The four outer planets, or gas giants (sometimes called Jovian planets), collectively make up 99 percent of the mass known to orbit the Sun. Jupiter and Saturn consist largely of hydrogen and helium. The bulk of Uranus and Neptune consist of “ices”, such as water, ammonia and methane. All four gas giants have rings, although only Saturn’s ring system is easily observed from Earth.
Jupiter
Jupiter (5.2 AU), at 318 Earth masses, masses 2.5 times all the other planets put together. It is composed largely of hydrogen and helium. Jupiter’s strong internal heat creates a number of semi-permanent features in its atmosphere, such as cloud bands and the Great Red Spot. Jupiter has sixty-three known satellites. The four largest, Ganymede, Callisto, Io, and Europa, show similarities to the terrestrial planets, such as volcanism and internal heating. Ganymede, the largest satellite in the Solar System, is larger than Mercury.
Saturn
Saturn (9.5 AU), famous for its extensive ring system, has similarities to Jupiter, such as its atmospheric composition. Saturn is far less massive, being only 95 Earth masses. Saturn has sixty known satellites (and three unconfirmed); two of which, Titan and Enceladus, show signs of geological activity, though they are largely made of ice. Titan is larger than Mercury and the only satellite in the Solar System with a substantial atmosphere.
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Uranus
Uranus (19.6 AU), at 14 Earth masses, is the lightest of the outer planets. Uniquely among the planets, it orbits the Sun on its side; its axial tilt is over ninety degrees to the ecliptic. It has a much colder core than the other gas giants, and radiates very little heat into space. Uranus has twenty-seven known satellites, the largest ones being Titania, Oberon, Umbriel, Ariel and Miranda.
Neptune
Neptune (30 AU), though slightly smaller than Uranus, is more massive (equivalent to 17 Earths) and therefore more dense. It radiates more internal heat, but not as much as Jupiter or Saturn. Neptune has thirteen known satellites. The largest, Triton, is geologically active, with geysers of liquid nitrogen. Triton is the only large satellite with a retrograde orbit. Neptune is accompanied in its orbit by a number of minor planets, termed Neptune Trojans.
Comets
Comets are small Solar System bodies, usually only a few kilometers across, composed largely of volatile ices. They have highly eccentric orbits, generally a perihelion within the orbits of the inner planets and an aphelion far beyond Pluto. When a comet enters the inner Solar System, its proximity to the Sun causes its icy surface to sublimate and ionise, creating a coma: a long tail of gas and dust often visible to the naked eye.
Short-period comets have orbits lasting less than two hundred years. Long-period comets have orbits lasting thousands of years. Short-period comets are believed to originate in the Kuiper belt, while long-period comets, such as Hale-Bopp, are believed to originate in the Oort cloud. Many comet groups, such as the Kreutz Sungrazers, formed from the breakup of a single parent. Some comets with hyperbolic orbits may originate outside the Solar System, but determining their precise orbits is difficult.
Centaurs
The centaurs, which extend from 9 to 30 AU, are icy comet-like bodies that orbit in the region between Jupiter and Neptune. The largest known centaur, 10199 Chariklo, has a diameter of between 200 and 250 km. The first centaur discovered, 2060 Chiron, has been called a comet since it develops a coma just as comets do when they approach the Sun.
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