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The scientific exploration of Venus

2015; Association of College and Research Libraries; Volume: 52; Issue: 10 Linguagem: Inglês

10.5860/choice.189887

1943-5975

Space exploration and regulation

The dawn of Venus exploration The Evening Star and the Morning StarEveryone has seen Venus, as a bright, starlike apparition in the evening sky, following the Sun down towards the horizon and setting a few hours later.At various other times of the year, there comes a brief season where an early bird can see Venus rise brilliantly before the Sun, climbing higher until it seems to dim and vanish as the sky brightens after sunrise.When it rises before the Sun, people have long called Venus the Morning Star; half an orbit later, when on the other side of the Sun so that the Sun sets first, Venus is the Evening Star.Before Copernicus promoted the idea that planets orbit the Sun, it was not obvious that these two phenomena were the same body, and early civilisations had distinct names for them.To the Greeks, they were Phosphoros and Hesperos.For much of the year, Venus sets and rises so near the Sun that we tend not to notice it.During the day, like the true stars at vastly greater distances, Venus is still overhead and just as bright, of course, but it is hard to see because the contrast with the dark sky is lost when the Sun is up.It can be studied during the day if a telescope is used to shut out most of the sunlight, and even with ordinary binoculars if you know where to look. 1 In any observations made over a period of a few months, Venus can be seen to exhibit lunarlike phases (Figure 1.1).As viewed from the Earth, Venus traces a flattened 'figure eight' pattern with the Sun at the centre (Figure 1.2).Sometimes, but rarely, Venus travels across the disc of the Sun when at its closest to the Earth, or behind the Sun when at its farthest, and we witness a transit.At closest approach to the Earth (inferior conjunction), not only is Venus near the Sun in the sky, making viewing difficult, but also the side facing us is dark (Figure 1.2).A fully illuminated disc can be seen, again with difficulty, only when Venus is on the far side of the Sun, at so-called superior conjunction.1 There are also reports of Venus seen with the naked eye during the day.The most famous of these involved Napoleon Bonaparte, whose attention was called to the phenomenon while he was delivering an open-air, midday address to a crowd in Luxembourg in 1796.A similar apparition was reported in Washington DC on the day of Abraham Lincoln's second inauguration in 1865.