French aeronauts Jacques Charles and Nicolas Robert descending at Nesles in France, watched by the Duc de Chartres and others, after travelling 27 miles from Les Tuileries, Paris, in the first manned hydrogen balloon flight © Hulton Archive/Getty Images
1783 – First manned flight of a hydrogen balloon
Jacques Alexandre César Charles launches his hydrogen balloon into the air, the first carrying humans. The enormous balloon, bulging with hydrogen gas, floated 550m above Paris with Jacques Charles and Nicolas-Louis Roaber suspended in the basket below. The flight, lasting 2 hours and 5 minutes, was tracked over a distance of 36km by horsemen who assembled beneath the contraption to ensure the audacious passengers were able to safely disembark.
Balloons previously relied on the use of air to fly, heated until it became lighter than its surroundings and floated upwards, however this process was limited because the balloon subsequently descended when the air cooled to its original temperature. The use of hydrogen negated this limitation of air and revolutionised balloon travel.
1997 – Eight planets in the Solar System align
Eight planets of the solar system align in a mesmerising formation visible from Earth. The stunning display by our solar system lasted until 8th December; during this week, Mercury, Mars, Venus, Jupiter and Saturn shone brightly in a row clearly visible to the naked eye. Meanwhile Uranus and Neptune could be seen beside them through binoculars alongside Pluto, whose observers required a telescope. Although the planets were again positioned in alignment in May 2000, their proximity to the Sun was too close to be visible from Earth.
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