Planet sizes-comparision

Planets:

A planet, as defined by the International Astronomical Union (IAU), is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals.

The 2006 definition of "planet" by the International Astronomical Union (IAU) states that in the solar system a planet is a celestial body that: is in orbit around the Sun, has sufficient mass so that it assumes a hydrostatic equilibrium (nearly round) shape, and has "cleared the neighbourhood" around its orbit.

The following section deals with the 8 planets of our solarsystem :

Mercury: Mercury is the closest planet to the sun, orbiting the sun once every 88 days. Mercury can be seen with naked eye with apparent magnitude upto -2.0. It can be seen only in mornings and evenings.Physically, Mercury is similar in appearance to the Moon. It is heavily cratered, has no natural satellites and no substantial atmosphere. It has a large iron core, which generates a magnetic field about 1% as strong as that of the Earth. It is an exceptionally dense planet due to the large size of its core. The surface temperatures on Mercury range from about-183 �C to 427 �C, with the subsolar point being the hottest and the bottoms of craters near the poles being the coldest.[more] [top]

Venus: Venus is the hottest planet in the solar system because of the presence of large amount of carbondioxide in its atmosphere which causes global warming on venus. Venus is also the second brightest object visible in the night sky next only to the moon. Venus has an apparent magnitude of upto -4.6. It orbits the sun once in every 224 days.Classified as a terrestrial planet, it is sometimes called Earth's "sister planet", because the two are similar in size, gravity, and bulk composition. Venus is covered with an opaque layer of highly reflective clouds of sulfuric acid, preventing its surface from being seen from space in visible light; this was a subject of great speculation until some of its secrets were revealed by planetary science in the twentieth century.[more]  [top]

Earth: The Earth is the third planet from the sun. It is also the largest of the terrestrial planets in the Solar System in diameter, mass and density. It is our home planet. Home to millions of species, including humans, Earth is the only place in the universe where life is known to exist.Scientific evidence indicates that the planet formed 4.54 billion years ago, and life appeared on its surface within a billion years. Since then, Earth's biosphere has significantly altered the atmosphere and other abiotic conditions on the planet, enabling the proliferation of aerobic organisms as well as the formation of the ozone layer which, together with Earth's magnetic field, blocks harmful radiation, permitting life on land. 71% of Earth's surface is covered by water and the rest 29% is covered by land.[more] [top]

Mars: Mars is the fourth planet from the Sun in the Solar System.It is also referred to as the "Red Planet" because of its reddish appearance as seen from Earth. 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. It is the site of Olympus Mons, the highest known mountain in the Solar System, and of Valles Marineris, the largest canyon. Mars has two moons, Phobos and Deimos, which are small and irregularly shaped. These may be captured asteroids. Mars can be seen from Earth with the naked eye. Its apparent magnitude can reach -2.9.[more] [top]

Jupiter: Jupiter is the fifth planet from the Sun and the largest planet within the Solar System. It is two and a half times as massive as all of the other planets in our Solar System combined. Jupiter, along with Saturn, Uranus and Neptune, is classified as a gas giant. The planet Jupiter is primarily composed of hydrogen with a small proportion of helium; it may also have a rocky core of heavier elements under high pressure. Because of its rapid rotation, Jupiter's shape is that of an oblate spheroid When viewed from Earth, Jupiter can reach an apparent magnitude of -2.8. [more] [top]

Saturn: Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Along with the planets Jupiter, Uranus and Neptune it is classified as a gas giant. The planet Saturn is composed of hydrogen, with small proportions of helium and trace elements. Saturn has a prominent system of rings, consisting mostly of ice particles with a smaller amount of rocky debris and dust. 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. Saturn's apparent magnitude can reach upto -0.24.[more] [top]

Uranus: 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 in modern times. Though it is visible to the naked eye like the five classical planets, it was never recognized as a planet by ancient observers due to its dimness and slow orbit. It was also the first planet to be discovered using a telescope. Like the other giant planets, Uranus has a ring system, a magnetosphere, and numerous moons. The Uranian system has a unique configuration among the planets because its axis of rotation is tilted sideways, nearly into the plane of its revolution about the Sun. [more] [top]

Neptune: Neptune is 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. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 Earth masses and less dense. Discovered on September 23, 1846,[1] Neptune was the first planet found by mathematical prediction rather than regular observation. Unexpected changes in the orbit of Uranus led astronomers to deduce the gravitational perturbation of an unknown planet. Neptune has the strongest winds of any planet in the solar system, measured as high as 2100 km/h.[more] [top]

See also: Conjunction Opposition