Mercury is the first planet in order from the Sun in our Solar System. It amazes human beings since the very beginning with its retrograde movements, and more recently with phases and similarities to the Moon. If you are looking for the top 10 interesting facts about the planet Mercury, you are in the right place - let's get started!
1. Interesting Facts Table
Hard, solid data! If you like straight to the point sources of information, here you have almost all the most important facts about the planet:
|Distance from Sun||36 million miles / 58 million km / 0.39 AU|
|Radius||1,516 miles / 2,439 km|
|Diameter||3,032 miles / 4,878 km|
|Mass||3.285 × 1023 kg (0.055 M⊕ / 5.5% Earths)|
|Length of Year (Orbit)||88 Earth days|
|Length of Day||59 Earth days|
|Temperatures||-290°F to 800°F / -180°C to 430°C|
|Moons||No - zero (0)|
2. What Color is Mercury?
Generally speaking, Mercury color is dark gray, very similar to the Moon.
However, it's hard to determine what does it even mean - "true". It's because the eyes of every human being perceive colors in a little different way. It may not even exist something like the true color - it's only how we, as people, perceive it in the current situation like phase, time, or place of observation.
3. Who Discovered Mercury?
The official discoverer of the planet is Galileo Galilei, who was first to observe it through a telescope in the 17th century.
However, this planet is visible to the naked, unarmed eye, and was therefore already known and observed by ancient civilizations, many centuries ago. That is why the real discoverer is impossible to determine - he/she probably did not even have a name, like we know today!
The exact date of the discovery of Mercury is unknown - the first historical mention comes from Sumerians, and it was about 3000 BC.
Retrograde is the movement of a celestial body that appears to be rotating or moving in the opposite direction to most bodies in a given orbital system. In the Solar System, the reverse motion has the opposite direction to the Earth's motion around the Sun, which, seen from the North Pole of the Sun, is counterclockwise.
Below you will find the nearest Mercury retrograde dates.
- February 16 – March 9, 2020
- June 17 – July 12, 2020
- October 13 – November 3, 2020
- January 30 – February 20, 2021
- May 29 – June 22, 2021
- September 27 – October 18, 2021
- January 14 – February 3, 2022
- May 10 – June 2, 2022
- September 9 – October 2, 2022
- December 29, 2022 – January 18, 2023
5. Size - The Smallest Planet
Mercury has a diameter of 3,031 miles / 4,878 km - less than half the diameter of the Earth - and it's the smallest planet in the Solar System (only dwarf planets like Pluto, Haumea, Makemake or Eris are smaller). Because of its little size, it is difficult to see it in the sky through binoculars or a telescope - but the easiest time to do this anyway is just before the sunrise or just after the sunset.
6. Atmosphere and Temperatures - Hot or Cold?
Surprisingly, being the closest planet to the Sun, Mercury is not the hottest one - it's only the second in terms of surface temperatures, right after Venus. Why's that? It's because Mercury does not have an atmosphere - there is nothing to retain the heat coming from the Sun, like the Venus have (thick, yet still!).
Mercury is the second densest planet in the Solar System - just after Earth.
8. Does Mercury Have Phases?
Yes, it has. Any planet that emits less light than the star it orbits can have phases depending on the viewer's position. Both the planets that are within the Earth's orbit - Mercury and Venus - have phases, but because they orbit the Sun closer than the Earth does, it's hard to see them.
The planet has no moons.
The only other Solar System planet that has no moons also is Venus.
10. Mercury Planet vs Moon
A lot of people compare this planet to our Moon, so let's check out what are the facts - are they really similar?
- Look. They are both just huge rocks with a lot of craters on the surface.
- No atmosphere.
- No liquid water on the surface.
|Object type||A planet||A moon|
|Mass||3.29 × 1023 kg||7.35 × 1022 kg|
|Radius||2439 km||1737 km|
|Surface gravity||3.7 m/s2||1.62 m/s2|
|Density||5.43 g/cm3||3.34 g/cm3|
|Distance from Sun (average)||58 million km||150 million km|
|Day (Earth time)||58d 15h 30m||27 days and change|
Hi, I'm Paweł! I'm an astrophotographer, full-time astrophotography blogger, passionate stargazer, and amateur astronomer. Here on Astro Photons, I share my astrophotography, space, and astronomy knowledge to help beginners to make their first steps into the hobbies.