First Recorded Transits and/or Sightings of Celestial Entities (Stars, Planets, Comets, etc.) in the Modern Era Timeline
By kay_will
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265 BCE
Mercury
Planets like Mercury have been seen by humans since the beginning of time and were observed by ancient Babylonian astronomers many millennia ago. In 1631, Pierre Gassendi was first to observe Mercury making a transit across the sun. A couple of years later, Giovanni Zupi discovered phases, indicating that the planet orbited the sun. Citation: Mercury BCMercury -
1032
Venus
Planets like Venus have been seen by humans since the beginning of time and were observed by ancient Babylonian astronomers many millennia ago. It is believed that Avicenna was the first to see Venus in transit, but he mistook Venus as a sunspot. In 1639, astronomer William Crabtree observed and recorded the first predicted transit of Venus. Citation: Venus BCVenus -
Earth
Because humans live on Earth, we would be unable to have a "first recorded sighting" of this planet. We also are unable to view Earth's transit. However, scientists predict what Earth's transits look like as if it were viewed from Mars. Also, in 1947, we got our first view of Earth from 100 miles in space. Citation: Earth -
Mars
Planets like Mars have been seen by humans since the beginning of time and were observed by ancient Sumerian astronomers many millennia ago. In 1609, Galileo Galilei was the first person to view Mars via a primitive telescope. Citation: Mars -
Jupiter
Planets like Jupiter have been seen by humans since the beginning of time and were observed by ancient Babylonian and ancient Chinese astronomers many millennia ago. In 1610, Galileo Galilei viewed Jupiter via telescope. Galileo was known to have discovered four of Jupiter's 67 known moons. Citation: Jupiter -
Saturn
Planets like Saturn have been seen by humans since the beginning of time and were observed by ancient Babylonian astronomers many millennia ago. In 1610, Galileo Galilei observed Saturn via telescope. In 1655, Christiaan Huygens discovered Saturn's rings with a telescope with greater magnification. Citation: Saturn -
Milky Way Galaxy
In 1610, Galileo Galilei first sighted the Milky Way with his rudimentary telescope. In 1755, Immanuel Kant proposed that the Milky Way was a large collection of stars held together by mutual gravity. In the 1920s, Edwin Hubble provided conclusive evidence that the spiral nebulae were actually other galaxies. Citation: Milky Way -
Halley's Comet
Halley's Comet had been seen by humans since the beginning of time and were observed by ancient Chinese astronomers many millennia ago. Edmond Halley predicted the return of the comet correctly using calculations by Isaac Newton. Citation: Halley's Comet -
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Neptune
Neptune was discovered in 1846 by Johann Gottfried Galle using calculations by Urbain Le Verrier and John Couch Adams. Galileo Galilei first saw Neptune in 1613. But, he mistook as a fixed star. Citation: Neptune -
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Pluto
In 1930, Clyde W. Tombaugh discovered Pluto. In 2006, Pluto was demoted from a planet to a dwarf planet. Citation: Pluto -
Oort Cloud
In 1950, Jan Oort proposed the idea of the existence of a sphere of icy bodies to explain the origins of comets with that take thousands of years to orbit the Sun. Citation: Oort Cloud -
Kuiper Belt
In 1987, Dave Jewitt discovered the Kuiper Belt. In 1951, Gerard Kuiper proposed that a belt of icy bodies might lay beyond Neptune. Citation: Kuiper Belt -
Hale-Bopp Comet
The Hale-Bopp Comet was discovered separately by Alan Hale and Thomas Bopp in 1995. Citation: Hale-Bopp Comet
