Solar System Secrets Trivia Quiz

Answer: Mercury

Being closest planet to the Sun, it is not surprising that Mercury has the greatest temperature range. Temperatures vary something like 600 deg C (1,090 deg F) between day and night, with a maximum temperature of around 427 deg C (800 deg F). The lack of atmosphere means that daytime heat rapidly dissipates with nightfall.

In the absence of sunlight, however, the polar regions do not rise above -93 deg C (-135 deg F).

Answer: Io

Jupiter's moon Io consists mostly of silicate rock and iron. The tidal forces caused by Jupiter and its orbital resonance with the moons Europa and Ganymede causes most of the internal heat, which results in the volcanic activity. Over 150 active volcanoes have been observed by passing spacecraft and, based on this, around 400 are estimated to exist.

Answer: Uranus

The axial tilt of Uranus, compared to the ecliptic plane of the solar system, is at about 98 degrees to the norm (or 82 degrees, depending on which pole is considered 'north'). There are various theories as to how this has arisen, the leading contender being that it was struck by one or more large celestial bodies at some point.

This has had some unusual effects with, for example, one hemisphere being in darkness for 42 Earth years whilst the other is facing the Sun. The dwarf planet Pluto is another with an unusual axial tilt.

Answer: Venus

All planets move around the Sun in the same ecliptic plane. Relative to the Sun's north, they rotate about the Sun in an anticlockwise (or counterclockwise) direction. Except for Venus (and possibly Uranus, depending on how its north pole is defined), the planets spin about their axes in an anticlockwise direction. Venus has a retrograde rotation, spinning slowly clockwise about its axis and taking 243 Earth days to rotate once.

Its orbit around the Sun takes 224.7 Earth days so its day is long than its year and slowly increasing at the rate of a few milliseconds per century.

It is not clear why it has a retrograde rotation.

Answer: Jupiter

Jupiter gets the prize for the Solar system's strongest planetary magnetic field. There are several contributing elements, such as the dynamo effect of the planet's spin on its core of metallic hydrogen. Sulphur dioxide, from the moon Io's volcanic eruptions, also contributes, being ionised and forming part of a plasma torus around the planet, which interacts with the planet's magnetic field.

Answer: Titan

Saturn's largest moon has a denser atmosphere than Earth and it is also four times thicker. Mostly composed of nitrogen, it also contains methane which, on breaking down, creates a haze, meaning seeing down to the surface it difficult. This meant that it was not until 2007 that the Cassini-Huygens mission confirmed the presence of lakes and seas filled with liquid hydrocarbons, mostly in the polar regions.

Answer: Neptune

Neptune tops the scales with wind speeds which can reach supersonic speeds of 2,400 kph (1,500 mph). Most winds blow in the opposite direction to the planet's rotation. Extreme differences in temperature between the equator and the poles are largely to blame. Solar radiation is weak so far out but the planet generates its own heat, emitting over 2.5 times the amount received from the Sun.

The atmospheric composition of hydrogen, helium and methane is another factor. For comparison, Earth tops out at around 370 kph (230 mph) whilst Jupiter achieves 640 kph (400 mph).

Answer: Ganymede

This planet-sized moon is one of Jupiter's 95-odd moons. At 5,268 km (3,273 mi), its diameter is larger than Mercury's 4,880 km (3,030 mi) but, due to its density, it has less surface gravity than Mercury or even Earth's moon. Saturn's Titan is another moon bigger than Mercury with Jupiter's Callisto being a shade under. Ganymede has a thin, mostly-oxygen, atmosphere and is able to generate its own magnetic field.

It has a large sub-surface ocean (or oceans), exceeding all of Earth's in volume.

Answer: Mars

At 21.9 km (72,000 ft) high, Olympus Mons on Mars is the tallest known volcano in the Solar system. It is a shield volcano, the youngest of the large volcanoes on Mars, and was last active around 25 million years ago. Rheasilvia on Vesta is of similar size but this was formed by an impact on an asteroid, not a volcano on a planet. Olympus Mons has its own named impact craters.

Answer: Enceladus

Enceladus, Saturn's sixth largest moon, exhibits cryo-vulcanism where water and other volatiles are ejected instead of molten rock. It has a sub-surface ocean which is heated by tidal forces created by the effect of Saturn's gravity on the moon. The pressurised water escapes through cracks in the ice shell, mostly in the 'tiger stripes' zone at the south pole.

More than 100 geysers have been noted, ejecting water hundreds of kilometres out from the surface.