On this day in 1982, all 9 planets aligned on the same side of the sun. This phenomenon (called ‘Syzygy’) has inspired us to into and beyond our solar system for today’s records:
Closest moon to a planet
Of all the moons in the Solar System, the one which orbits closest to its planet is the tiny Martian satellite, Phobos.
Phobos is 9,378 km 5,827 miles from the centre of Mars - which corresponds to 5,981 km 3,716 miles above the Martian surface.
Phobos is a small potato-shaped irregular moon, measuring 27 x 22 x 18 km (17 x 14 x 11 miles). It is dark and covered with dusty craters and is almost certainly an asteroid which was captured by Mars' gravity many millions of years ago.
Closest planet to a star
The closest planet to any star discovered so far is a Jupiter-sized gas giant orbiting the star OGLE-TR-3. This 'hot Jupiter' orbits just 3.5 million km (2.1 million miles) from its parent star and has an orbital period of just 28 hr 33 min. OGLE-TR-3 is a G-type star (similar to the Sun) some 1,500 parsecs (4,900 light years) away.
Fastest planet
Mercury, which orbits the Sun at an average distance of 57.9 million km (35.9 million miles), has a orbital period of 87.9686 days, thus giving the highest average speed in orbit of 172,248 kph (107,030 mph). This is almost twice as fast as the Earth.
Highest cliffs in the Solar System
NASA's Voyager 2 probe encountered the planet Uranus and its collection of moons in 1986. The small moon Miranda, with a diameter of 472 km, has a surface made up of a jumble of bizarre geological features. One of the most prominent of these features is an enormous cliff with a vertical relief of about 20km 12 miles. This cliff, named Verona Rupes, is more than ten times higher than the walls of the Grand Canyon on Earth. That this towering cliff is so huge is made even more remarkable by the small size of Miranda itself. The white material exposed in the cliff face is probably mostly water ice.
Tallest clouds
The tallest eye-wall clouds are a massive vortex of clouds, similar to a hurricane, which were discovered at Saturn's south pole in 2006. Unlike Jupiter's Great Red Spot, this feature exhibits the classic eye wall clouds of a hurricane on Earth. This south polar vortex is the only time an eye wall has been detected on another planet and, with heights of between 35 and 70 km (18-46 miles), are roughly 5 times higher than occur in terrestrial hurricanes.
