Tuesday, the Planet Venus will pass directly between the Sun and the Earth – scientists around the world will be gathering data – mostly to assist on being able to look for planets that orbit other distant stars and cause very tiny changes to the light that reaches Earth from those far away stars.<\/p>\n
http:\/\/www.transitofvenus.org\/<\/p>\n
http:\/\/en.wikipedia.org\/wiki\/Transit_of_Venus<\/p>\n
Venus will cross into the path of the sun at 6:04 PM (EDT) on Tuesday (don’t look at the sun!)\u00a0\u00a0 Compared to the sun, Venus is a tiny speck.\u00a0\u00a0 This transit is important because the orbit of Venus is inclined about 3 degrees from Earth’s orbit, and the length it takes the Earth and Venus to return to the same relative position takes 243 years.\u00a0\u00a0\u00a0 When the two planets are in the right relative position, there is a transit usually followed by another 8 years later – then it is another gap of 121 or 105 years.<\/p>\n
German mathematician and astronomer Johannes Kepler had figured out enough about planetary motion that he predicted the transits of Venus in 1631 and 1639 (Kepler died in 1630). Kepler struggled with trying to reconcile what the math and physics were telling him with his belief in God, and coping with the dangers of not wanting to anger the Catholic church – his mother at one point was accused of being a witch.<\/p>\n
Eventually figuring out that planets orbit the sun in an ellipse with the sun at one of the focal points – everything started to fall into place. While Copernicus had correctly realized the Earth orbits the sun, and it wasn’t the Sun orbiting the Earth once a year, he believed the orbits of the planets were circular. Kepler was trying to determine why orbits were not lining up properly and realized that orbits of planets are elliptical, not a perfect round circle operating in the same plane and that the Sun is not at the center of the solar system, but at a focal point of the elliptical orbits.<\/p>\n
While astronomers knew the relative distances between the planets by 1639, they didn’t have an accurate measure of the average distance from the Earth to the Sun is (called an Astronomical Unit – or AU). After missing the transit in 1631 (it wasn’t visible in Europe and nobody was watching for it on other parts of the planet), the 1639 event predicted by Kepler gave a close estimate of the distance – some small details still unknown at that time made the result slightly inaccurate. By 1761 and 1769, the ability to move around the planet and to keep accurate time had improved to the point that a much better number was calculated (still about 3% inaccurate)<\/p>\n","protected":false},"excerpt":{"rendered":"
Tuesday, the Planet Venus will pass directly between the Sun and the Earth – scientists around the world will be gathering data – mostly to assist on being able to look for planets that orbit other distant stars and cause … Continue reading