10 Facts about planet Mercury

The first of our facts about planet Mercury is that it is the closest planet to the Sun and is a bit of a recluse. Due to its proximity to the sun, it is not easily visible except during twilight. Interestingly, Mercury rotates on its axis three times for every two orbits around the Sun. Prior to 1965, it was believed that the same side of Mercury always faced the Sun. However, this was later proven to be incorrect. Thirteen times a century, Mercury can be observed from Earth passing across the face of the Sun in an event called a transit.

1 A year on Mercury is just 88 days long, which is just another of our facts about the planet Mercury

Mercury, the smallest planet in our solar system, is a fascinating celestial body. A year on Mercury is just 88 Earth days long, which is incredibly short compared to Earth’s 365-day year. One solar day on Mercury lasts the equivalent of 176 Earth days, while the sidereal day lasts 59 Earth days.

Did you know this other fact about planet Mars?

Mercury is nearly tidally locked to the Sun, and over time, this has slowed the rotation of the planet to almost match its orbit around the Sun. Mercury also has the highest orbital eccentricity of all the planets, with its distance from the Sun ranging from 46 to 70 million km.

2 The planet Mercury is the smallest planet in our solar system

Mercury is one of five planets visible to the naked eye, and it’s just 4,879 kilometres across its equator, compared with 12,742 kilometres for Earth. Put simply, Earth is three times the size of Mercury, as shown below.

3 Mercury’s distance from the Sun and orbital eccentricity

4 Mercury is the second-densest planet

Despite its small size, Mercury is very dense. Each cubic centimetre has a density of 5.4 grams, with only the Earth having a higher density. This is largely due to Mercury being composed mainly of heavy metals and rock.

Did you know?

Mercury’s core has more iron than any other planet in the solar system. Scientists think this had to do with its formation and early life.

5 Another of the facts about planet Mercury is that it is wrinkly

As the iron core of the planet cooled and contracted, the surface of the planet became wrinkled. Scientists have named these wrinkles Lobate Scarps, which can be up to a mile high and hundreds of miles long.

Did you know?

Lobate scarps are most notably found on Mercury and the Moon. These cliffs vary from tens to over a thousand kilometres in length and from about 100 meters to 3 kilometres in altitude. As seen from above, they have curved or scalloped edges.

6 Next in facts about planet Mercury is that it has a molten core

In recent years, scientists from NASA have come to believe that the solid iron core of Mercury could, in fact, be molten. Normally, the core of smaller planets cools rapidly, but after extensive research, the results were not in line with those expected from a solid core.

Did you know this?

Scientists now believe the core to contain a lighter element, such as sulfur, which would lower the melting temperature of the core material. It is estimated that Mercury’s core makes up 42% of its volume, while the Earth’s core makes up 17%.

7 Mercury is the second hottest planet

Mercury is only the second hottest planet in our solar system, despite being the closest planet to the Sun. The title of the hottest planet goes to Venus, which has a thick atmosphere that traps heat and causes a runaway greenhouse effect

Did you know?

The side of Mercury that faces the Sun sees temperatures of up to 427°C, while on the other side, this can be as low as -173°C. This is because the planet has no atmosphere to help regulate the temperature.

8 Mercury has the most craters of any planet in our system

Mercury is the smallest planet in the Solar System and has a unique surface. Unlike many other planets, which “self-heal” through natural geological processes, the surface of Mercury is covered in craters. These are caused by numerous encounters with asteroids and comets.

Did you know this?

Most Mercurian craters are named after famous writers and artists. Any crater larger than 250 kilometres in diameter is referred to as a Basin. The Caloris Basin is the largest impact crater on Mercury, and it covers approximately 1,550 km in diameter. It was discovered in 1974 by the Mariner 10 probe.

9 Only two spacecraft have visited Mercury

Only two spacecraft have ever visited Mercury: Mariner 10 and Messenger. Owing to its proximity to the Sun, Mercury is a difficult planet to visit. During 1974 and 1975, Mariner 10 flew by Mercury three times; during this time, they mapped just under half of the planet’s surface.

Did you know this fact about planet Mercury?

On August 3rd, 2004, the Messenger probe was launched from Cape Canaveral Air Force Station. This historic event marked the first spacecraft to visit the planet since the mid-1970s.

10 Mercury is named after a Roman God

Mercury is named for the Roman messenger to the gods, among other things. The exact date of Mercury’s discovery is unknown, as it predates its first historical mention. One of the first times Mercury was mentioned was by the Sumerians around 3,000 BC.

Did you know?

The inhabitants of Mesopotamia from about 3500 B.C. to about 2000 B.C. are referred to as the Sumerians, who named the planet after the god of writing, Nabu.