The Solar System and the Sun.

I. Learn active vocabulary:

celestial object – небесный объект

scattered disc – рассеянный диск

Oort cloud – облако Оорта

to permeate – проникать, пронизывать, распространяться

interstellar - межзвездный

perihelion - перигелий

aphelion - афелий

sequence – последовательность, очередность, порядок, последствия

exception - исключение

to accept - принимать

parent star – звезда прародительница

nuclear fusion – ядерный синтез

moderately - средне

dim - тусклый

to exhaust - истощать

luminosity - свечение

to explode - взрываться

accretion - увеличение

tenuous – тонкий, незначительный, разряженный

solar flare – солнечная вспышка

coronal mass ejection – выброс корональной массы

interplanetary medium – межпланетное пространство

heliospheric current sheet – гелиосферный солнечный ветер

to shield – заслонять, защищать

II. Read and translate the text:

The Solar System consists of the Sun and those celestial objects bound to it by gravity. These objects are the eight planets and their 166 known moons, four dwarf planets and billions of small bodies, including asteroids, icy Kuiper belt objects, comets, meteoroids, and interplanetary dust.

These objects are grouped in a number of distinct regions. Moving outwards from the Sun, the major components are four terrestrial inner planets, an asteroid belt, four gas giant outer planets, the Kuiper belt, the scattered disc, and ultimately the hypothetical Oort cloud. A stream of charged particles from the Sun, called the solar wind, defines the heliosphere which permeates the Solar System out to around the scattered disc.

In order of their distances from the Sun, the eight planets are:

• Mercury

• Venus

• Earth

• Mars

• Jupiter

• Saturn

• Uranus

• Neptune

Four smaller objects are classified as dwarf planets as of mid-2008, though the list is expected to grow:

• Ceres

• Pluto

• Makemake

• Eris

Six of the planets and two of the dwarf planets are in turn orbited by natural satellites, usually termed “moons” after Earth’s Moon, and each of the outer planets is encircled by planetary rings of dust and other particles.

Terminology

The zones of the Solar system: the inner solar system, the

asteroid belt, the giant planets (Jovians) and the Kuiper belt.

Sizes and orbits not to scale.

Objects orbiting the Sun are divided into three classes: planets, dwarf planets, and small Solar System bodies.

On August 24, 2006, the International Astronomical Union defined the term “planet” for the first time, prompted by the discovery of Eris and subsequent discussions over its classification. A planet is any body in orbit around the Sun that has enough mass to form itself into a spherical shape and has cleared its immediate neighborhood of all smaller objects. By this definition, the Solar System has eight known planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. Pluto was demoted from planetary status, as it has not cleared its orbit of surrounding Kuiper belt objects.

A dwarf planet, as defined by the International Astronomical Union (IAU), is a celestial body orbiting the Sun that is massive enough to be rounded by its own gravity but which has not cleared its neighboring region of planetesimals and is not a satellite. By this definition, the Solar System has four known dwarf planets: Ceres, Pluto, Makemake, and Eris. Other objects that may become classified as dwarf planets are Sedna, Orcus, and Quaoar. Dwarf planets that orbit in the trans-Neptunian region are called “plutoids.”

The remainder of the objects in orbit around the Sun are small Solar System bodies (SSSBs).

Natural satellites, or moons, are those objects in orbit around planets, dwarf planets and SSSBs, rather than the Sun itself.

Astronomers usually measure distances within the Solar System in astronomical units (AU). One AU is the approximate distance between the Earth and the Sun, or roughly 149,598,000 km (93,000,000 mi). Pluto is roughly 38 AU from the Sun while Jupiter lies at roughly 5.2 AU. One light-year, the best known unit of interstellar distance, is roughly 63,240 AU. A body’s distance from the Sun varies in the course of its year. Its closest approach to the Sun is called its perihelion, while its farthest distance from the Sun is called its aphelion.

Informally, the Solar System is sometimes divided into separate zones. The inner Solar System includes the four terrestrial planets and the main asteroid belt. Some define the outer Solar System as comprising everything beyond the asteroids. Since the discovery of the Kuiper belt, others define it as the region beyond Neptune, with the four gas giants considered a separate “middle zone”.