Mercury is innermost and smallest planet of the Solar System.
Mercury, Solar System, inner planets, rocky planet, Sun, planet, astronomy, geography
Mercury is one of the planets of the Solar System, an inner planet closest to the Sun. It is the smallest planet in the Solar System; 2 of the moons are larger than Mercury: Ganymede (orbiting Jupiter) and Titan (orbiting Saturn).
Mercury is a rocky planet (terrestrial planet), the second densest in the Solar System (5.43 g/cm³ or 0.196 lb/in³), due to its iron core. When observed from the Earth, it is always close to the Sun, never moving further away than 22 degrees from it, and it has phases, similarly to the Moon.
Diameter: 4,879.4 km (3,032 mi or 0.383 Earths)
Mass: 3.302×10²³ kg (7.3 ×10²³ lb or 0.055 Earths)
Avarage density: 5.43 g/cm³ (0.196 lb/in³)
Surface gravity: 0.378 g
Surface temperature: -180 °C – 430 °C (-292 °F – 806 °F)
Number of moons: 0
Rotation period: 58.6 days
Axial tilt: 2.1°
Average distance from the Sun:
57,909,176 km = 35,980,000 mi = 0.38 AU = 3.22 light minutes
Orbital eccentricity: 0.206
Orbital period: 87.97 days (3/2 of the rotation period)
Recorded observations of Mercury date back to the first millennium B.C. Before the 4th century B.C., Greek astronomers believed it to be two separate planets, one visible at sunrise, the other at sunset. The former was named Apollo, the latter Hermes. Later, Pythagoras realized that the two planets were the same. The English name for the planet comes from the Romans, who named it after the Roman god Mercury. They identified him with Hermes, the Greek messenger of the gods, the protector of travelers, and guide of dead souls.
Comparatively little information is available about the planet. Two space probes have visited Mercury. The first of these was Mariner 10, which mapped only 45% of its surface. The second was MESSENGER, launched in 2004, flying by Mercury several times and taking pictures of nearly the entire surface. In 2011, it was placed in orbit around the planet (Messenger probe).
Mercury is one of the planets of the Solar System, an inner planet closest to the Sun. It is the smallest planet in the Solar System; two moons are larger than Mercury: Ganymede (orbiting Jupiter) and Titan (orbiting Saturn).
Mercury is a rocky planet (terrestrial planet), the second densest in the solar system (5.43 g/cm³ or 0.196 lb/in³), due to its iron core.
When observed from the Earth, it is always close to the Sun, never moving further away than 22 degrees from it, and it has phases, similarly to the Moon.
The surface of the planet is similar to that of the Moon: cratered plateaus and smooth volcanic plains alternate, with fold mountains, rocky regions and valleys. The circular Caloris Basin, 1,400 km (867 mi) in diameter, may have been created by a powerful impact.
The surface of Mercury receives 6 times more radiation from the Sun than the Earth. The day side of the planet is very hot, while the night side is very cold. This is due to the lack of an atmosphere that would equalize the temperature and the planet's very slow rotation. From among all the planets, the albedo of Mercury is the lowest.
As for material and chemical composition, Mercury is a terrestrial planet. It has nearly the same density as the Earth does, with an iron content of about twice that of Earth. The iron-nickel core takes up around 75% of the total radius of the planet. This core represents 80% of the total mass. The strength of Mercury’s magnetic field is only 1% that of the Earth.
The inner planets of the Solar System are terrestrial planets while the outer planets are gas giants.
The formation of the Sun and the planets started with the contraction of a dust cloud about 4.5 billion years ago.
The Earth is a rocky planet with a solid crust and oxygen in its atmosphere.
Jupiter is the largest planet of the Solar System, it has two and a half times the mass of all the other planets combined.
The three important laws describing planetary motion were formulated by Johannes Kepler.
Possible traces of water and life are sought on Mars.
Space probes and Mars rovers examine the structure of Mars and possible traces of life.
The diameter of our galaxy is about 100,000 light years; it contains more than 100 billion stars, one of which is our Sun.
Neptune is the outermost planet of the Solar System, the smallest of the giant planets
The largest satellite of Pluto is Charon.
Saturn is the second largest planet in the Solar System, easily recognisable by its rings.
The Earth is composed of several spherical layers.
The Cassini spacecraft was exploring Saturn and its moons for nearly 20 years.
Studying Ceres and Vesta will help us learn more about the early history of the Solar System and how rocky planets are formed.
The New Horizons space probe was launched in 2006, with the objective to study Pluto and the Kuiper Belt.
The orbits of the 8 planets in our Solar System are elliptical.
The diameter of the Sun is about 109 times that of the Earth. Most of its mass consists of hydrogen.
Uranus is the 7th planet from the Sun, a gas giant.
Venus is the 2nd planet from the Sun, the brightest object on the night sky (after the Moon).