Who Discovered Mercury?
QUICK ANSWER
Mercury has no single discoverer. It's been visible to the naked eye since prehistoric times and was documented by ancient civilizations including the Sumerians, Babylonians, Egyptians, and Greeks. The earliest known records of Mercury observations date back to at least 3,000 years ago in Mesopotamia.
Mercury is one of the five planets visible from Earth without a telescope, which means there was never a moment of discovery. People have been looking up at Mercury for thousands of years. The history isn't about discovery so much as about how different cultures understood what they were seeing.
When was Mercury first observed?
The earliest known records of Mercury observations come from Sumerian astronomers around 3,000 years ago, with detailed records preserved on Babylonian clay tablets known as the MUL.APIN. Ancient Egyptian and Chinese astronomers also tracked Mercury independently. The Greeks initially thought Mercury was two separate objects, calling it Apollo when it appeared at sunrise and Hermes at sunset; later astronomers, including Pythagoras around 500 BCE, realized it was the same body in both cases.
Did Galileo discover Mercury?
No, but Galileo was the first to observe Mercury through a telescope, in the early 1600s. Mercury was already well known by that point. Galileo's telescope wasn't strong enough to clearly resolve Mercury's phases (the way the planet appears lit at different angles), but later astronomers including Giovanni Zupi confirmed Mercury showed phases like the Moon's, which was important evidence for the heliocentric model. According to NASA, modern Mercury exploration didn't begin until the Mariner 10 mission in 1974.
Why is Mercury hard to see?
Mercury sits so close to the Sun that it never appears far from it in our sky. From Earth, Mercury is only visible briefly after sunset or before sunrise, when the Sun is just below the horizon. The window is short, usually less than an hour, and Mercury sits low on the horizon during that time, where atmospheric haze tends to dim it further. Astronomers say it's the most overlooked of the naked-eye planets, partly because spotting it requires timing and clear skies.
When did we first send spacecraft to Mercury?
NASA's Mariner 10 became the first spacecraft to fly past Mercury, in 1974 and 1975, returning the first close-up images of the planet's cratered surface. NASA's MESSENGER mission was the first to orbit Mercury, from 2011 to 2015, mapping the entire planet in detail. The ESA and JAXA BepiColombo mission, launched in 2018, is currently making flybys before entering Mercury orbit and is expected to begin its primary science mission in the coming years.
Mercury wasn't discovered by anyone, exactly. It's been visible to the naked eye and known to humans for as long as people have been looking up. The real discovery story is about how slowly we've learned what's actually there, from a moving point of light in the sky to a small iron-rich world with permanent ice in its polar craters.
More Mercury Questions
Mystery Question?
Mystery Question?
Mystery Question?