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Mar 4, 1543
mercury
It probably wasn't until the Copernican model was developed – that the planets are believed to travel around the Sun – that astronomers really understood that Mercury was another planet; just like the Earth. Copernicus published his model in 1543, describing how the Earth was just another planet orbiting the Sun. -
venus
Galileo in 1610 was first to observe that Venus had a visible disk and that it had phases like the moon so perhaps he could be considered to have discovered the modern Venus. Captain James Cook made observations of a "Transit of Venus" in 1776-1779. -
jupiter
Jupiter's moons are too! Galileo discovered four of the larger moons: Io, Europa, Ganymede and Callisto in 1610. Most of the other moons were found by the Voyager spacecraft during its flyby. -
mars
In 1659, Christian Huygens discovered a strange feature on the surface of the Red Planet. It was later called the Syrtis Major. We have been scared of Martians ever since. In 1802, one scientist was so convinced there was life on Mars that he wanted to draw huge figures in the snow to signal the Martians! -
saturn
Saturn has been known since prehistoric times. Galileo was the first to observe it with a telescope in 1610; he noted its odd appearance but was confused by it. Early observations of Saturn were complicated by the fact that the Earth passes through the plane of Saturn's rings every few years as Saturn moves in its orbit. A low resolution image of Saturn therefore changes drastically. It was not until 1659 that Christiaan Huygens correctly inferred the geometry of the rings. Saturn's rings remain -
Uranus
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Neptune
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moon
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moon
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pluto
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Mercury has no moon
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venus has no moon
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earth has one moon
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mars has two moons Phobos and Deimos.
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jupiter has one moon Jovian
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Saturn has lots of moons (33)