You might know that Mercury is the first and smallest planet in our solar system, but did you know it orbits the Sun in only 88 days?
One of the most mysterious planets in our universe, Mercury is hard to observe from Earth due to its proximity to the Sun. But with advances in technology, we have been able to study this tiny planet, and what we've learnt is mind-blowing! Let's dive into some interesting facts about Mercury.
1: It's the fastest planet
Mercury is the fastest planet in our Solar System, orbiting the Sun at an average speed of 170503.5 kilometres or 105,946 miles per hour.
2: It's the smallest planet
Mercury is the smallest planet in our Solar System, with a diameter of only 4,879 kilometres, which is about 38% of Earth’s diameter.
3: It's the second densest planet
Mercury is the second densest planet in our Solar System, after Earth, with a density of 5.4 grams per cubic centimetre, which is due to its large iron core.
4: It has no moons
Mercury has no moons or rings, making it one of the only two planets in our Solar System without any natural satellites (the other one is Venus).
5: There is no atmosphere
Mercury has no atmosphere to speak of. Its atmosphere dissipated soon after the planet formed, about 4.6 billion years ago. This means Mercury has no weather, wind, or clouds. It also means that the sky on Mercury is always black, even during the day.
6: Mercury has a very thin exosphere
Instead of an atmosphere, Mercury has a very thin exosphere. Mercury's exosphere is a layer of gas that surrounds the planet but is not bound by gravity. The exosphere is composed mainly of hydrogen, helium, oxygen, sodium, potassium, and calcium.
7: Mercury's orbit is egged shaped
Mercury has a very elongated orbit, which makes it the planet with the highest orbital eccentricity in our Solar System. Its distance from the Sun varies from 46 to 70 million km, which is a difference of 24 million km or 53%.
8: Time moves a little slower there
Mercury has a very slow rotation, which makes it the planet with the longest solar day in our Solar System. One solar day on Mercury (the time from noon to noon on the planet’s surface) lasts 176 Earth days, which is longer than its orbital period of 88 Earth days.
9: It has a weak magnetic field
Mercury has a very weak magnetic field, which is only about 1% of Earth’s magnetic field. Scientists are unsure how Mercury generates its magnetic field since its core is thought to be partially molten.
10: It's named after a god
Mercury is named after the Roman god of commerce and communication, who was known for his speed and agility.
11: There are a few dints on Mercury
Mercury has a very cratered surface, which is similar to the Moon’s surface. The craters on Mercury range in size from a few meters to hundreds of kilometres in diameter. Some of the largest and most prominent craters are named after famous artists, musicians, and writers, such as Bach, Joplin, and Shakespeare.
12: Mercury has wrinkles
Mercury has some unique surface features, such as lobate scarps (long cliffs that form when the crust shrinks as the core cools), smooth plains (flat areas that may have been formed by lava flows), and volcanic vents (holes that may have been used by magma to reach the surface). Some of these mysterious features include:
the Caloris Basin, a huge impact crater that measures about 1,550 km in diameter and is one of the largest in the Solar System.
the Great Valley, a giant depression that stretches for about 1,000 km and is the longest valley on any planet.
the Hollows, small pits that are found in some craters and may have been created by the sublimation of volatile materials.
13: There are quakes on Mercury
Mercury has some interesting geological activity, such as
tectonics, which is the movement of the crust due to internal forces
volcanism, which is the eruption of lava and gas from the interior
quakes, which occur when the ground moves due to tectonic or volcanic activity.
14: Mercury has shooting stars
Mercury has some spectacular phenomena, such as:
shooting stars, which are meteors that burn up in the exosphere and may grant wishes to those who see them
transits, which occur when Mercury passes in front of the Sun as seen from Earth, which happens about 13 times per century.
eclipses, which occur when Mercury passes behind the Sun as seen from Earth, eclipses happen about twice per year
comets, icy bodies that orbit the Sun, which sometimes pass close to Mercury, leaving behind trails of dust and gas.
15: There may be resources on Mercury
Mercury has potential resources, such as water ice, metals, and minerals. Scientists believe water ice can be found in some permanently shadowed craters near the poles, where the temperature is below -173°C (so cold!). It is also believed that there are metals in Mercury's core and the crust, such as iron, nickel, and gold. Potential minerals may include silicates, sulfates, and carbonates.
16: We've sent spacecraft to Mercury
Mercury has some scientific missions, such as Mariner 10, MESSENGER, and BepiColombo. Mariner 10 was the first spacecraft to visit Mercury in 1974 and 1975, and it mapped about 45% of the surface. MESSENGER was the second spacecraft to visit Mercury in 2008 and 2009, and it orbited the planet from 2011 to 2015, mapping 100% of the surface. BepiColombo is the third spacecraft to visit Mercury, it was launched in 2018 and will arrive in 2025, carrying two orbiters and one lander.
17: Mercury has a molten core
Mercury has a molten core which is surprising for such a small planet and may be due to the presence of sulfur or another light element that lowers the melting point of the core material.
18: Mercury has extreme temperatures
Mercury experiences the most extreme temperature fluctuations in our solar system. During the day, temperatures can soar up to 430°C (800°F), while at night they can plummet to as low as -180°C (-290°F). This is due to Mercury’s lack of a significant atmosphere, which on other planets, serves to moderate temperature extremes. Interestingly, despite its proximity to the Sun, Mercury is not the hottest planet. Venus holds that title due to its thick heat-trapping atmosphere.
19: It's a long walk to Mercury
Embarking on a journey to Mercury is quite an adventure! If you traveled to Mercury by bike it would take approximately 700.33 years. Flying at the average cruising speed of a commercial plane, it would take 15.35 years. If you decided to take a leisurely walk to Mercury, it would take around 2941.40 years, based on the average walking speed on Earth.
These calculations assume a direct path to Mercury at its closest approach to Earth, which is about 124402291.2 kilometres (77.3 million miles) away.
20: Mercury is a movie star
Mercury has been featured in various science fiction movies, often portrayed as a harsh and desolate world due to its proximity to the Sun. Here are some notable mentions:
'Sunshine' - involves a mission to reignite the Sun and includes scenes set close to Mercury.
'Collision Earth' - a TV movie where Mercury is thrown out of orbit and set on a collision course with Earth.
Explore Mercury in depth.