In the year 1612, when Galileo Galileo

Galileo looked at the planet Jupiter through a telescope,

he may have accidentally discovered a new planet,

although he had no idea at the time.

It wouldn't be for another 300 years until astronomers found what

Galileo had missed and the process of discovery was unlike that for any other

planet. Today it remains the most distant and least explored planet in the solar system.

Learn more about Neptune, the solar system's most distant planet and the eighth planet from the sun,

on this episode of Everything Everywhere Daily. Neptune doesn't get a lot of attention. It's technically the furthest planet from the Sun, but that was only because Pluto got demoted.

The story of Neptune, as far as this episode is concerned, starts with its discovery.

Neptune is, on average, 30 astronomical units from the Sun. An astronomical

unit is the average distance from the Sun to the Earth. Because of its

distance you can't observe Neptune with the naked eye. That means despite

thousands of years of gazing at the night sky, humans had no clue that Neptune

existed until the advent of telescopes. As I mentioned in the introduction there's a good chance that Galileo had actually of

as I mentioned in the introduction, there's a good chance that Galleo had actually observed Neptune without even knowing it.

When Galleo was taking observations with his telescope in 1612,

he kept detailed notes about what he saw.

His sketches of stars made during observations of Jupiter on December 28th, 1612, and

January 27, 1613, correspond to where Neptune would have been on those dates.

However, he would have had no clue that what he was looking at was a planet.

It looked just like a star, and Neptune would have been in retrograde at the time, so it would barely

...