Top 10 Solar System facts

Jupiter moons. Jupiter's moons, especially Io (spot on the left), are powerful sources of auroras on Jupiter. These arise from electric currents along field lines, generated by a dynamo mechanism due to the relative motion between the rotating planet and the moving moon.

Shakespeare's characters. William Herschel, Englishman, discoverer of Uranus and its major moons, was very patriotic for naming. He originally named Uranus as "George Star" to honour king of England, but the name was changed later.

Iapetus. The ridge is 13 km high, 20 km wide and 1300 km long. Its origin is not known, but considering the amount of craters, it's safe to assume that it is a very old geological feature.

59%. Moon's libration changes the angle from which the Moon is seen, allowing about 59% of its surface to be seen from the Earth (but only half at any instant). Moon's libration is caused by the eccentricity of its orbit around Earth and by a slight inclination of its axis of rotation.

Venus is much brighter than other planets. It is due to its proximity to the Sun (source of light), and bright clouds of sulfuric acid in its atmosphere.

On Mars. Olympus Mons (Latin for Mount Olympus) is a large shield volcano on the planet Mars, having a height of nearly 22 km (14 mi). Being a shield volcano, it has a very low profile. The average slope on the volcano's flanks is only 5°. Because of that, an observer standing on the Martian surface would be unable to view the entire profile of the volcano, even from a great distance.

Uranus is the seventh planet from the Sun. It has the coldest planetary atmosphere in the Solar System, with a minimum temperature of 49 K (−224 °C; −371 °F).

Moons of Jupiter. The four largest moons of Jupiter were discovered in 1610 by Galileo Galilei and are today known as the Galilean moons. From the end of the 19th century, dozens of much smaller Jovian moons have been discovered and have received the names of lovers or daughters of the Roman god Jupiter or his Greek equivalent Zeus.

Eight. These are Mercury, the Venus, the Earth, Mars, the Jupiter, the Saturn, the Uranus and the Neptune. The Pluto is excluded from the list since 2006, and it is classified as one of dwarf planets (not even the largest of them).

Cosmic rays. The only efficient protection against high energetic cosmic radiation, one we are granted with, is Earth's magnetic field. Both during a long flight to Mars and through the stay on the planet, that did not form electromagnetic field, astronauts would be exposed to ionization.